wdiff draft-ietf-httpbis-message-signatures-05.txt draft-ietf-httpbis-message-signatures-06.txt

HTTP A. Backman, Ed.
Internet-Draft Amazon
Intended status: Standards Track J. Richer
Expires: 10 December 2021 14 February 2022 Bespoke Engineering
M. Sporny
Digital Bazaar
8 June
13 August 2021

Signing

HTTP Messages
draft-ietf-httpbis-message-signatures-05 Message Signatures
draft-ietf-httpbis-message-signatures-06

Abstract

This document describes a mechanism for creating, encoding, and
verifying digital signatures or message authentication codes over
content within
components of an HTTP message. This mechanism supports use cases
where the full HTTP message may not be known to the signer, and where
the message may be transformed (e.g., by intermediaries) before
reaching the verifier. This document also describes a means for
requesting that a signature be applied to a subsequent HTTP message
in an ongoing HTTP exchange.

Note to Readers

_RFC EDITOR: please remove this section before publication_

Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/
(https://lists.w3.org/Archives/Public/ietf-http-wg/).

Working Group information can be found at https://httpwg.org/
(https://httpwg.org/); source code and issues list for this draft can
be found at https://github.com/httpwg/http-extensions/labels/
signatures (https://github.com/httpwg/http-extensions/labels/
signatures).

Status of This Memo

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provisions of BCP 78 and BCP 79.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 4
1.1. Requirements Discussion . . . . . . . . . . . . . . . . . 4 5
1.2. HTTP Message Transformations . . . . . . . . . . . . . . 5
1.3. Safe Transformations . . . . . . . . . . . . . . . . . . 5 6
1.4. Conventions and Terminology . . . . . . . . . . . . . . . 6 7
1.5. Application of HTTP Message Signatures . . . . . . . . . 8 9
2. HTTP Message Signature Covered Content Components . . . . . . . . . . . 8 . . . . . . . . 10
2.1. HTTP Headers Fields . . . . . . . . . . . . . . . . . . . . . . 9 . 11
2.1.1. Canonicalized Structured HTTP Headers Fields . . . . . . . . 10 11
2.1.2. Canonicalization Examples . . . . . . . . . . . . . . 10 11
2.2. Dictionary Structured Field Members . . . . . . . . . . . 11 12
2.2.1. Canonicalization Examples . . . . . . . . . . . . . . 11 12
2.3. Specialty Content Fields . Components . . . . . . . . . . . . . . . 11
2.3.1. Request Target . . . 13
2.3.1. Signature Parameters . . . . . . . . . . . . . . . . 12 14
2.3.2. Signature Parameters Method . . . . . . . . . . . . . . . . 13
2.4. Creating the Signature Input String . . . . . . . . . 15
2.3.3. Target URI . . 14
3. HTTP Message Signatures . . . . . . . . . . . . . . . . . . . 16
3.1. Creating a Signature . . . .
2.3.4. Authority . . . . . . . . . . . . . . 17
3.2. Verifying a Signature . . . . . . . . 16
2.3.5. Scheme . . . . . . . . . . 18
3.2.1. Enforcing Application Requirements . . . . . . . . . 20
3.3. Signature Algorithm Methods . . . . 17
2.3.6. Request Target . . . . . . . . . . . 21
3.3.1. RSASSA-PSS using SHA-512 . . . . . . . . 17
2.3.7. Path . . . . . . 21
3.3.2. RSASSA-PKCS1-v1_5 using SHA-256 . . . . . . . . . . . 22
3.3.3. HMAC using SHA-256 . . . . . . . 19
2.3.8. Query . . . . . . . . . . 22
3.3.4. ECDSA using curve P-256 DSS and SHA-256 . . . . . . . 23
3.3.5. JSON Web Signature (JWS) algorithms . . . . . . . 19
2.3.9. Query Parameters . . 23
4. Including a Message Signature in a Message . . . . . . . . . 23
4.1. The 'Signature-Input' HTTP Header . . . . . . . 20
2.3.10. Status Code . . . . . 24
4.2. The 'Signature' HTTP Header . . . . . . . . . . . . . . . 24
4.3. Multiple Signatures . 21
2.3.11. Request-Response Signature Binding . . . . . . . . . 21
2.4. Creating the Signature Input String . . . . . . . . . 25
5. IANA Considerations . . 23

3. HTTP Message Signatures . . . . . . . . . . . . . . . . . . . 26
5.1. HTTP 25
3.1. Creating a Signature Algorithms Registry . . . . . . . . . . . 26
5.1.1. Registration Template . . . . . . . 25
3.2. Verifying a Signature . . . . . . . . . 26
5.1.2. Initial Contents . . . . . . . . . 27
3.2.1. Enforcing Application Requirements . . . . . . . . . 27
5.2. HTTP 29
3.3. Signature Metadata Parameters Registry . Algorithm Methods . . . . . . 28
5.2.1. Registration Template . . . . . . . . . 29
3.3.1. RSASSA-PSS using SHA-512 . . . . . . . 28
5.2.2. Initial Contents . . . . . . . 30
3.3.2. RSASSA-PKCS1-v1_5 using SHA-256 . . . . . . . . . . . 29
5.3. HTTP Signature Specialty Content Identifiers Registry 31
3.3.3. HMAC using SHA-256 . . 29
5.3.1. Registration Template . . . . . . . . . . . . . . . 31
3.3.4. ECDSA using curve P-256 DSS and SHA-256 . 29
5.3.2. Initial Contents . . . . . . 31
3.3.5. JSON Web Signature (JWS) algorithms . . . . . . . . . 32
4. Including a Message Signature in a Message . . . 29
6. Security Considerations . . . . . . 32
4.1. The 'Signature-Input' HTTP Field . . . . . . . . . . . . 33
4.2. The 'Signature' HTTP Field . 30
7. References . . . . . . . . . . . . . . 33
4.3. Multiple Signatures . . . . . . . . . . . 30
7.1. Normative References . . . . . . . . 34
5. Requesting Signatures . . . . . . . . . . 30
7.2. Informative References . . . . . . . . . . 36
5.1. The Accept-Signature Field . . . . . . . 31
Appendix A. Detecting HTTP Message Signatures . . . . . . . . 37
5.2. Processing an Accept-Signature . 32
Appendix B. Examples . . . . . . . . . . . . 37
6. IANA Considerations . . . . . . . . . . 32
B.1. Example Keys . . . . . . . . . . . 38
6.1. HTTP Signature Algorithms Registry . . . . . . . . . . . 32
B.1.1. Example Key RSA test 38
6.1.1. Registration Template . . . . . . . . . . . . . . . . 33
B.1.2. Example RSA PSS Key 39
6.1.2. Initial Contents . . . . . . . . . . . . . . . . . 33
B.1.3. Example ECC P-256 Test Key . 39
6.2. HTTP Signature Metadata Parameters Registry . . . . . . . 41
6.2.1. Registration Template . . . . . 34
B.1.4. Example Shared Secret . . . . . . . . . . . 41
6.2.2. Initial Contents . . . . . 35
B.2. Test Cases . . . . . . . . . . . . . 41
6.3. HTTP Signature Specialty Component Identifiers
Registry . . . . . . . . . . 35
B.2.1. Minimal Signature Header using rsa-pss-sha512 . . . . 36
B.2.2. Header Coverage using rsa-pss-sha512 . . . . . . . . 36
B.2.3. Full Coverage using rsa-pss-sha512 . . 41
6.3.1. Registration Template . . . . . . . 37
B.2.4. Signing a Response using ecdsa-p256-sha256 . . . . . 37
B.2.5. Signing a Request using hmac-sha256 . . . . 42
6.3.2. Initial Contents . . . . . 38
Acknowledgements . . . . . . . . . . . . . 42
7. Security Considerations . . . . . . . . . . . 38
Document History . . . . . . . . 43
8. References . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . 44
8.1. Normative References . . . . . . . . . . . . . . 41

1. Introduction . . . . 44
8.2. Informative References . . . . . . . . . . . . . . . . . 45
Appendix A. Detecting HTTP Message integrity and authenticity are important security properties
that are critical to the secure operation of Signatures . . . . . . . . . 46
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 46
B.1. Example Keys . . . . . . . . . . . . . . . . . . . . . . 46
B.1.1. Example Key RSA test . . . . . . . . . . . . . . . . 46
B.1.2. Example RSA PSS Key . . . . . . . . . . . . . . . . . 47
B.1.3. Example ECC P-256 Test Key . . . . . . . . . . . . . 48
B.1.4. Example Shared Secret . . . . . . . . . . . . . . . . 49
B.2. Test Cases . . . . . . . . . . . . . . . . . . . . . . . 49
B.2.1. Minimal Signature Using rsa-pss-sha512 . . . . . . . 50
B.2.2. Selective Covered Components using rsa-pss-sha512 . . 50
B.2.3. Full Coverage using rsa-pss-sha512 . . . . . . . . . 51
B.2.4. Signing a Response using ecdsa-p256-sha256 . . . . . 52
B.2.5. Signing a Request using hmac-sha256 . . . . . . . . . 53
B.3. TLS-Terminating Proxies . . . . . . . . . . . . . . . . . 53
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 55
Document History . . . . . . . . . . . . . . . . . . . . . . . . 56
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 59

1. Introduction

Message integrity and authenticity are important security properties
that are critical to the secure operation of many HTTP applications.
Application developers typically rely on the transport layer to
provide these properties, by operating their application over [TLS].
However, TLS only guarantees these properties over a single TLS
connection, and the path between client and application may be
composed of multiple independent TLS connections (for example, if the
application is hosted behind a TLS-terminating gateway or if the
client is behind a TLS Inspection appliance). In such cases, TLS
cannot guarantee end-to-end message integrity or authenticity between
the client and application. Additionally, some operating
environments present obstacles that make it impractical to use TLS,
or to use features necessary to provide message authenticity.
Furthermore, some applications require the binding of an application-
level key to the HTTP message, separate from any TLS certificates in
use. Consequently, while TLS can meet message integrity and
authenticity needs for many HTTP-based applications, it is not a
universal solution.

This document defines a mechanism for providing end-to-end integrity
and authenticity for components of an HTTP message. The mechanism
allows applications to create digital signatures or message
authentication codes (MACs) over only the components of the message
that are meaningful and appropriate for the application. Strict
canonicalization rules ensure that the verifier can verify the
signature even if the message has been transformed in any of the many
ways permitted by HTTP.

The signing mechanism described in this document consists of three
parts:

* A common nomenclature and canonicalization rule set for the
different protocol elements and other components of HTTP messages.

* Algorithms for generating and verifying signatures over HTTP
message components using this nomenclature and rule set.

* A mechanism for attaching a signature and related metadata to an
HTTP message.

This document also provides a mechanism for one party to signal to
another party that a signature is desired in one or more subsequent
messages. This optional negotiation mechanism can be used along with
opportunistic or application-driven message signatures by either
party.

1.1. Requirements Discussion

HTTP permits and sometimes requires intermediaries to transform
messages in a variety of ways. This may result in a recipient
receiving a message that is not bitwise equivalent to the message
that was originally sent. In such a case, the recipient will be
unable to verify a signature over the raw bytes of the sender's HTTP
message, as verifying digital signatures or MACs requires both signer
and verifier to have the exact same signature input. Since the exact
raw bytes of the message cannot be relied upon as a reliable source
of signature input, the signer and verifier must derive the signature
input from their respective versions of the message, via a mechanism
that is resilient to safe changes that do not alter the meaning of
the message.

For a variety of reasons, it is impractical to strictly define what
constitutes a safe change versus an unsafe one. Applications use
HTTP in a wide variety of ways, and may disagree on whether a
particular piece of information in a message (e.g., the body, or the
"Date" header field) is relevant. Thus a general purpose solution
must provide signers with some degree of control over which message
components are signed.

HTTP applications may be running in environments that do not provide
complete access to or control over HTTP messages (such as a web
browser's JavaScript environment), or may be using libraries that
abstract away the details of the protocol (such as the Java
HTTPClient library (https://openjdk.java.net/groups/net/httpclient/
intro.html)). These applications need to be able to generate and
verify signatures despite incomplete knowledge of the HTTP message.

1.2. HTTP Message Transformations

As mentioned earlier, HTTP explicitly permits and in some cases
requires implementations to transform messages in a variety of ways.
Implementations are required to tolerate many of these
transformations. What follows is a non-normative and non-exhaustive
list of transformations that may occur under HTTP, provided as
context:

* Re-ordering of header fields with different header field names
([MESSAGING], Section 3.2.2).

* Combination of header fields with the same field name
([MESSAGING], Section 3.2.2).

* Removal of header fields listed in the "Connection" header field
([MESSAGING], Section 6.1).

* Addition of header fields that indicate control options
([MESSAGING], Section 6.1).

* Addition or removal of a transfer coding ([MESSAGING],
Section 5.7.2).

* Addition of header fields such as "Via" ([MESSAGING],
Section 5.7.1) and "Forwarded" ([RFC7239], Section 4).

1.3. Safe Transformations

Based on the definition of HTTP and the requirements described above,
we can identify certain types of transformations that should not
prevent signature verification, even when performed on message
components covered by the signature. The following list describes
those transformations:

* Combination of header fields with the same field name.

* Reordering of header fields with different names.

* Conversion between different versions of the HTTP protocol (e.g.,
HTTP/1.x to HTTP/2, or vice-versa).

* Changes in casing (e.g., "Origin" to "origin") of any case-
insensitive components such as header field names, request URI
scheme, or host.

* Addition or removal of leading or trailing whitespace to a header
field value.

* Addition or removal of "obs-folds".

* Changes to the "request-target" and "Host" header field that when
applied together do not result in a change to the message's
effective request URI, as defined in Section 5.5 of [MESSAGING].

Additionally, all changes to components not covered by the signature
are considered safe.

1.4. Conventions and Terminology

The terms "HTTP message", "HTTP request", "HTTP response", "absolute-
form", "absolute-path", "effective request URI", "gateway", "header
field", "intermediary", "request-target", "sender", and "recipient"
are used as defined in [MESSAGING].

The term "method" is to be interpreted as defined in Section 4 of
[SEMANTICS].

For brevity, the term "signature" on its own is used in this document
to refer to both digital signatures and keyed MACs. Similarly, the
verb "sign" refers to the generation of either a digital signature or
keyed MAC over a given input string. The qualified term "digital
signature" refers specifically to the output of an asymmetric
cryptographic signing operation.

In addition to those listed above, this document uses the following
terms:

HTTP Message Signature:
A digital signature or keyed MAC that covers one or more portions
of an HTTP message. Note that a given HTTP Message can contain
multiple HTTP Message Signatures.

Signer:
The entity that is generating or has generated an HTTP Message
Signature. Note that multiple entities can act as signers and
apply separate HTTP Message Signatures to a given HTTP Message.

Verifier:
An entity that is verifying or has verified an HTTP Message
Signature against an HTTP Message. Note that an HTTP Message
Signature may be verified multiple times, potentially by different
entities.

HTTP Message Component:
A portion of an HTTP message that is capable of being covered by
an HTTP Message Signature.

HTTP Message Component Identifier:

A value that uniquely identifies a specific HTTP Message Component
in respect to a particular HTTP Message Signature and the HTTP
Message it applies to.

HTTP Message Component Value:
The value associated with a given component identifier within the
context of a particular HTTP Message. Component values are
derived from the HTTP Message and are usually subject to a
canonicalization process.

Covered Components:
An ordered set of HTTP message component identifiers for fields
(Section 2.1) and specialty components (Section 2.3) that
indicates the set of message components covered by the signature,
not including the "@signature-params" specialty identifier itself.
The order of this set is preserved and communicated between the
signer and verifier to facilitate reconstruction of the signature
input.

Signature Input:
The sequence of bytes processed by the HTTP Message Signature
algorithm to produce the HTTP Message Signature. The signature
input is generated by the signer and verifier using the covered
components set and the HTTP Message.

HTTP Message Signature Algorithm:
A cryptographic algorithm that describes the signing and
verification process for the signature. When expressed
explicitly, the value maps to a string defined in the HTTP
Signature Algorithms Registry defined in this document.

Key Material:
The key material required to create or verify the signature. The
key material is often identified with an explicit key identifier,
allowing the signer to indicate to the verifier which key was
used.

Creation Time:
A timestamp representing the point in time that the signature was
generated, as asserted by the signer.

Expiration Time:
A timestamp representing the point in time at which the signature
expires, as asserted by the signer. A signature's expiration time
could be undefined, indicating that the signature does not expire
from the perspective of the signer.

The term "Unix time" is defined by [POSIX.1], Section 4.16
(http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
V1_chap04.html#tag_04_16).

This document contains non-normative examples of partial and complete
HTTP messages. Some examples use a single trailing backslash '' to
indicate line wrapping for long values, as per [RFC8792]. The "\"
character and leading spaces on wrapped lines are not part of the
value.

1.5. Application of HTTP Message Signatures

HTTP Message Signatures are designed to be a general-purpose security
mechanism applicable in a wide variety of circumstances and
applications. In order to properly and safely apply HTTP Message
Signatures, an application or profile of this specification MUST
specify all of the following items:

* The set of component identifiers (Section 2) that are expected and
required. For example, an authorization protocol could mandate
that the "Authorization" header be covered to protect the
authorization credentials and mandate the signature parameters
contain a "created" parameter, while an API expecting HTTP message
bodies could require the "Digest" header to be present and
covered.

* A means of retrieving the key material used to verify the
signature. An application will usually use the "keyid" parameter
of the signature parameters (Section 2.3.1) and define rules for
resolving a key from there, though the appropriate key could be
known from other means.

* A means of determining the signature algorithm used to verify the
signature is appropriate for the key material. For example, the
process could use the "alg" parameter of the signature parameters
(Section 2.3.1) to state the algorithm explicitly, derive the
algorithm from the key material, or use some pre-configured
algorithm agreed upon by the signer and verifier.

* A means of determining that a given key and algorithm presented in
the request are appropriate for the request being made. For
example, a server expecting only ECDSA signatures should know to
reject any RSA signatures, or a server expecting asymmetric
cryptography should know to reject any symmetric cryptography.

An application using signatures also has to ensure that the verifier
will have access to all required information to re-create the
signature input string. For example, a server behind a reverse proxy
would need to know the original request URI to make use of
identifiers like "@target-uri". Additionally, an application using
signatures in responses would need to ensure that clients receiving
signed responses have access to all the signed portions, including
any portions of the request that were signed by the server.

The details of this kind of profiling are the purview of the
application and outside the scope of this specification.

2. HTTP Message Components

In order to allow signers and verifiers to establish which components
are covered by a signature, this document defines component
identifiers for components covered by an HTTP Message Signature, a
set of rules for deriving and canonicalizing the values associated
with these component identifiers from the HTTP Message, and the means
for combining these canonicalized values into a signature input
string. The values for these items MUST be accessible to both the
signer and the verifier of the message, which means these are usually
derived from aspects of the HTTP message or signature itself.

Some HTTP message components can undergo transformations that change
the bitwise value without altering meaning of the component's value
(for example, the merging together of header fields with the same
name). Message component values must therefore be canonicalized
before it is signed, to ensure that a signature can be verified
despite such intermediary transformations. This document defines
rules for each component identifier that transform the identifier's
associated component value into such a canonical form.

Component identifiers are serialized using the production grammar
defined by RFC8941, Section 4 [RFC8941]. The component identifier
itself is an "sf-string" value and MAY define parameters which are
included using the "parameters" rule.

component-identifier = sf-string parameters

Note that this means the value of the component identifier itself is
encased in double quotes, with parameters following as a semicolon-
separated list, such as ""cache-control"", ""date"", or ""@signature-
params"".

The following sections define component identifier types, their
parameters, their associated values, and the canonicalization rules
for their values. The method for combining component identifiers
into the signature input is defined in Section 2.4.

2.1. HTTP Fields

The component identifier for an HTTP field is the lowercased form of
its field name. While HTTP field names are case-insensitive,
implementations MUST use lowercased field names (e.g., "content-
type", "date", "etag") when using them as component identifiers.

Unless overridden by additional parameters and rules, the HTTP field
value MUST be canonicalized with the following steps:

1. Create an ordered list of the field values of each instance of
the field in the message, in the order that they occur (or will
occur) in the message.

2. Strip leading and trailing whitespace from each item in the list.

3. Concatenate the list items together, with a comma "," and space "
" between each item.

The resulting string is the canonicalized component value.

2.1.1. Canonicalized Structured HTTP applications.
Application developers typically rely on Fields

If value of the transport layer to
provide these properties, by operating their application over [TLS].
However, TLS only guarantees these properties over the HTTP field in question is a structured field
([RFC8941]), the component identifier MAY include the "sf" parameter.
If this parameter is included, the HTTP field value MUST be
canonicalized using the rules specified in Section 4 of RFC8941
[RFC8941]. For example, this process will replace any optional
internal whitespace with a single TLS
connection, and space character.

The resulting string is used as the path between client component value in Section 2.1.

2.1.2. Canonicalization Examples

This section contains non-normative examples of canonicalized values
for header fields, given the following example HTTP message:

Host: www.example.com
Date: Tue, 07 Jun 2014 20:51:35 GMT
X-OWS-Header: Leading and application may be
composed trailing whitespace.
X-Obs-Fold-Header: Obsolete
line folding.
X-Empty-Header:
Cache-Control: max-age=60
Cache-Control: must-revalidate
X-Dictionary: a=1, b=2;x=1;y=2, c=(a b c)
The following table shows example canonicalized values for header
fields, given that message:

Table 1: Non-normative examples of multiple independent TLS connections (for example, if header field
canonicalization.

2.2. Dictionary Structured Field Members

An individual member in the
application is hosted behind value of a TLS-terminating gateway or if Dictionary Structured Field is
identified by using the
client parameter "key" on the component identifier
for the field. The value of this parameter is behind a TLS Inspection appliance). In such cases, TLS
cannot guarantee end-to-end message integrity or authenticity between the client and application. Additionally, some operating
environments key being
identified, without any parameters present obstacles on that make it impractical to use TLS,
or to use features necessary to provide message authenticity.
Furthermore, some applications require the binding of an application-
level key to in the HTTP message, separate from any TLS certificates
original dictionary.

An individual member in
use. Consequently, while TLS can meet message integrity and
authenticity needs for many HTTP-based applications, it the value of a Dictionary Structured Field is not
canonicalized by applying the serialization algorithm described in
Section 4.1.2 of RFC8941 [RFC8941] on a
universal solution. Dictionary containing only
that item.

2.2.1. Canonicalization Examples

This document defines a mechanism section contains non-normative examples of canonicalized values
for providing end-to-end integrity
and authenticity Dictionary Structured Field Members given the following example
header field, whose value is known to be a Dictionary:

X-Dictionary: a=1, b=2;x=1;y=2, c=(a b c)
The following table shows example canonicalized values for content within different
component identifiers, given that field:

+======================+=================+
| Component Identifier | Component Value |
+======================+=================+
| "x-dictionary";key=a | 1 |
+----------------------+-----------------+
| "x-dictionary";key=b | 2;x=1;y=2 |
+----------------------+-----------------+
| "x-dictionary";key=c | (a, b, c) |
+----------------------+-----------------+

Table 2: Non-normative examples of
Dictionary member canonicalization.

2.3. Specialty Components

Message components not found in an HTTP message. The mechanism
allows applications to create digital signatures or message
authentication codes (MACs) over only that content within field can be included in the message
that is meaningful
signature input by defining a component identifier and appropriate for the application. Strict
canonicalization rules ensure that method for its component value.

To differentiate specialty component identifiers from HTTP fields,
specialty component identifiers MUST start with the verifier can verify "at" "@"
character. This specification defines the following specialty
component identifiers:

@signature-params The signature even if the message has been transformed in any metadata parameters for this
signature. (Section 2.3.1)

@method The method used for a request. (Section 2.3.2)

@target-uri The full target URI for a request. (Section 2.3.3)

@authority The authority of the many
ways permitted by HTTP. target URI for a request.
(Section 2.3.4)

@scheme The mechanism described in this document consists scheme of three parts:

* A common nomenclature and canonicalization rule set for the
different protocol elements and other content within HTTP
messages.

* Algorithms target URI for generating and verifying signatures over HTTP
message content using this nomenclature and rule set.

* A mechanism a request. (Section 2.3.5)

@request-target The request target. (Section 2.3.6)

@path The absolute path portion of the target URI for attaching a signature and related metadata to an
HTTP message.

1.1. Requirements Discussion

HTTP permits and sometimes requires intermediaries to transform
messages in request.
(Section 2.3.7)

@query The query portion of the target URI for a variety request.
(Section 2.3.8)

@query-params The parsed query parameters of ways. This may result in the target URI for a recipient
receiving
request. (Section 2.3.9)

@status The status code for a response. (Section 2.3.10).

@request-response A signature from a request message that is not bitwise equivalent to the message
that was originally sent. In such a case, the recipient will resulted
in this response message. (Section 2.3.11)

Additional specialty component identifiers MAY be
unable to verify a signature over the raw bytes of defined and
registered in the sender's HTTP
message, as verifying digital signatures or MACs requires both signer
and verifier to Signatures Specialty Component Identifier
Registry. (Section 6.3)

2.3.1. Signature Parameters

HTTP Message Signatures have metadata properties that provide
information regarding the exact same signed content. Since the raw
bytes of the message cannot be relied upon signature's generation and verification,
such as signed content, the
signer set of covered components, a timestamp, identifiers for
verification key material, and verifier must derive other utilities.

The signature parameters component identifier is "@signature-params".

The signature parameters component value is the signed content from their
respective versions serialization of the message, via a mechanism that is resilient
to safe changes that do not alter
signature parameters for this signature, including the meaning covered
components set with all associated parameters. These parameters
include any of the message.

For a variety following:

* "created": Creation time as an "sf-integer" UNIX timestamp value.
Sub-second precision is not supported. Inclusion of reasons, it this
parameter is impractical to strictly define what
constitutes a safe change versus RECOMMENDED.

* "expires": Expiration time as an unsafe one. Applications use
HTTP in a wide variety of ways, and may disagree on whether a
particular piece of information in a message (e.g., the body, or the
"Date" header field) "sf-integer" UNIX timestamp
value. Sub-second precision is relevant. Thus a general purpose solution
must provide signers with some degree of control over which not supported.

* "nonce": A random unique value generated for this signature.

* "alg": The HTTP message
content is signed. signature algorithm from the HTTP applications may Message
Signature Algorithm Registry, as an "sf-string" value.

* "keyid": The identifier for the key material as an "sf-string"
value.

Additional parameters can be running defined in environments that do not provide
complete access to or control over the HTTP messages (such Signature Parameters
Registry (Section 6.2.2).

The signature parameters component value is serialized as a web
browser's JavaScript environment), or may be
parameterized inner list using libraries that
abstract away the details rules in Section 4 of the protocol (such RFC8941
[RFC8941] as follows:

1. Let the Java
HTTPClient library (https://openjdk.java.net/groups/net/httpclient/
intro.html)). These applications need to output be able to generate and
verify signatures despite incomplete knowledge of an empty string.

2. Determine an order for the HTTP message.

1.2. HTTP Message Transformations

As mentioned earlier, HTTP explicitly permits and in some cases
requires implementations to transform messages in a variety of ways.
Implementations are required to tolerate many component identifiers of these
transformations. What follows the covered
components. Once this order is a non-normative and non-exhaustive
list of transformations that may occur under HTTP, provided as
context:

* Re-ordering of header fields with different header field names
([MESSAGING], Section 3.2.2).

* Combination of header fields with chosen, it cannot be changed.
This order MUST be the same field name
([MESSAGING], Section 3.2.2).

* Removal of header fields listed order as used in creating the "Connection" header field
([MESSAGING], Section 6.1).

* Addition of header fields that indicate control options
([MESSAGING], Section 6.1).

* Addition or removal of a transfer coding ([MESSAGING],
Section 5.7.2).

* Addition
signature input (Section 2.4).

3. Serialize the component identifiers of header fields such the covered components,
including all parameters, as "Via" ([MESSAGING],
Section 5.7.1) and "Forwarded" ([RFC7239], an ordered "inner-list" according to
Section 4).

1.3. Safe Transformations

Based on the definition 4.1.1.1 of HTTP RFC8941 [RFC8941] and append this to the requirements described above,
we can identify certain types
output.

4. Determine an order for any signature parameters. Once this order
is chosen, it cannot be changed.

5. Append the parameters to the "inner-list" in the chosen order
according to Section 4.1.1.2 of transformations RFC8941 [RFC8941], skipping
parameters that should are not
prevent signature verification, even when performed on content
covered by the available or not used for this message
signature.

6. The following list describes those
transformations:

* Combination of header fields with output contains the same field name.

* Reordering of header fields with different names.

* Conversion between different versions signature parameters component value.

Note that the "inner-list" serialization is used for the covered
component value instead of the HTTP protocol (e.g.,
HTTP/1.x to HTTP/2, or vice-versa).

* Changes "sf-list" serialization in casing (e.g., "Origin" order to "origin") of any case-
insensitive content
facilitate this value's inclusion in message fields such as header field names, request URI
scheme, or host.

* Addition or removal of leading or trailing whitespace to the
"Signature-Input" field's dictionary, as discussed in Section 4.1.

This example shows a header
field value.

* Addition or removal of "obs-folds".

* Changes to canonicalized value for the "request-target" and "Host" header field parameters of a
given signature:

NOTE: '\' line wrapping per RFC 8792

("@target-uri" "@authority" "date" "cache-control" "x-empty-header" \
"x-example");keyid="test-key-rsa-pss";alg="rsa-pss-sha512";\
created=1618884475;expires=1618884775

Note that when
applied together do not result an HTTP message could contain multiple signatures, but only
the signature parameters used for the current signature are included
in a change the entry.

2.3.2. Method

The "@method" component identifier refers to the message's
effective HTTP method of a
request URI, as defined in Section 5.5 message. The component value of [MESSAGING].

Additionally, all changes to content not covered is canonicalized by taking
the signature are
considered safe.

1.4. Conventions and Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted value of the method as described in
BCP 14 [RFC2119] [RFC8174] when, a string. Note that the method name is
case-sensitive as per [SEMANTICS] Section 9.1, and conventionally
standardized method names are uppercase US-ASCII. If used, the
"@method" component identifier MUST occur only when, they appear once in all
capitals, as shown here.

The terms "HTTP message", "HTTP request", "HTTP response", "absolute-
form", "absolute-path", "effective the covered
components.

For example, the following request URI", "gateway", "header
field", "intermediary", "request-target", "sender", and "recipient"
are message:

POST /path?param=value HTTP/1.1
Host: www.example.com

Would result in the following "@method" value:

"@method": POST

If used as defined in [MESSAGING]. a response message, the "@method" component identifier
refers to the associated component value of the request that
triggered the response message being signed.

2.3.3. Target URI

The term "method" is "@target-uri" component identifier refers to be interpreted the target URI of a
request message. The component value is the full absolute target URI
of the request, potentially assembled from all available parts
including the authority and request target as defined described in
[SEMANTICS] Section 4 of
[SEMANTICS]. 7.1. If used, the "@target-uri" component
identifier MUST occur only once in the covered components.

For brevity, example, the term "signature" on its own is following message sent over HTTPS:

POST /path?param=value HTTP/1.1
Host: www.example.com

Would result in the following "@target-uri" value:

"@target-uri": https://www.example.com/path?param=value

If used in this document
to refer to both digital signatures and keyed MACs. Similarly, a response message, the
verb "sign" "@target-uri" component identifier
refers to the generation associated component value of either a digital signature or
keyed MAC over a given input string. the request that
triggered the response message being signed.

2.3.4. Authority

The qualified term "digital
signature" "@authority" component identifier refers specifically to the output authority
component of the target URI of an asymmetric
cryptographic signing operation.

In addition to those listed above, this document uses the following
terms:

Signer:

The entity that is generating or has generated an HTTP Message
Signature.

Verifier:
An entity that is verifying or has verified an HTTP Message
Signature against an HTTP Message. Note that an request message, as defined
in [SEMANTICS] Section 7.2. In HTTP Message
Signature may be verified multiple times, potentially by different
entities.

Covered Content:
An ordered list of content identifiers for headers (Section 2.1)
and specialty content (Section 2.3) that indicates 1.1, this is usually conveyed
using the metadata "Host" header, while in HTTP 2 and message content that HTTP 3 it is covered by conveyed
using the signature, not
including ":authority" pseudo-header. The value is the "@signature-params" specialty field itself.

HTTP Signature Algorithm:
A cryptographic algorithm that describes fully-
qualified authority component of the signing and
verification process for request, comprised of the signature. When expressed
explicitly, host
and, optionally, port of the request target, as a string. The
component value maps MUST be normalized according to a string defined in the HTTP
Signature Algorithms Registry defined rules in this document.

Key Material:
The key material required to create or verify
[SEMANTICS] Section 4.2.3. Namely, the signature. The
key material host name is often identified with an explicit key identifier,
allowing the signer to indicate normalized to
lowercase and the verifier which key was
used.

Creation Time:
A timestamp representing default port is omitted. If used, the point "@authority"
component identifier MUST occur only once in time that the signature was
generated, as asserted by covered components.

For example, the signer.

Expiration Time:
A timestamp representing following request message:

POST /path?param=value HTTP/1.1
Host: www.example.com

Would result in the point following "@authority" component value:

"@authority": www.example.com

If used in time at which a response message, the signature
expires, as asserted by "@authority" component identifier
refers to the signer. A signature's expiration time
could be undefined, indicating associated component value of the request that
triggered the signature does not expire
from response message being signed.

2.3.5. Scheme

The "@scheme" component identifier refers to the perspective scheme of the signer.

The term "Unix time" is defined by [POSIX.1], Section 4.16
(http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
V1_chap04.html#tag_04_16).

This document contains non-normative examples target
URL of partial and complete the HTTP messages. Some examples use a single trailing backslash '' to
indicate line wrapping for long values, as per [RFC8792]. request message. The "\"
character and leading spaces on wrapped lines are not part of component value is the
value.

1.5. Application of HTTP Message Signatures

HTTP Message Signatures are designed to be scheme
as a general-purpose security
mechanism applicable string as defined in a wide variety of circumstances and
applications. In order [SEMANTICS] Section 4.2. While the scheme
itself is case-insensitive, it MUST be normalized to properly and safely apply HTTP Message
Signatures, an application or profile of this specification lowercase for
inclusion in the signature input string. If used, the "@scheme"
component identifier MUST
specify all of occur only once in the following items:

* The set of content identifiers (Section 2) that are expected and
required. covered components.

For example, an authorization protocol could mandate
that the "Authorization" header be covered to protect the
authorization credentials and mandate the signature parameters
contain a "created" parameter, while an API expecting HTTP following request message
bodies could require requested over plain HTTP:

POST /path?param=value HTTP/1.1
Host: www.example.com

Would result in the following "@scheme" value:

"@scheme": http

If used in a response message, the "Digest" header "@scheme" component identifier
refers to be present and
covered.

* A means the associated component value of retrieving the key material used request that
triggered the response message being signed.

2.3.6. Request Target

The "@request-target" component identifier refers to verify the
signature. An application will usually use full request
target of the "keyid" parameter HTTP request message, as defined in [SEMANTICS]
Section 7.1. The component value of the signature parameters (Section 2.3.2) and define rules for
resolving a key from there, though request target can take
different forms, depending on the appropriate key could be
known from other means.

* A means type of determining request, as described
below. If used, the signature algorithm used "@request-target" component identifier MUST
occur only once in the covered components.

For HTTP 1.1, the component value is equivalent to verify the
signature content request target
portion of the request line. However, this value is appropriate for more difficult
to reliably construct in other versions of HTTP. Therefore, it is
NOT RECOMMENDED that this identifier be used when versions of HTTP
other than 1.1 might be in use.

The origin form value is combination of the key material. absolute path and query
components of the request URL. For example, the process could use following request
message:

POST /path?param=value HTTP/1.1
Host: www.example.com

Would result in the "alg" parameter following "@request-target" component value:

"@request-target": /path?param=value

The following request to an HTTP proxy with the absolute-form value,
containing the fully qualified target URI:

GET https://www.example.com/path?param=value HTTP/1.1

Would result in the following "@request-target" component value:

"@request-target": https://www.example.com/path?param=value

The following CONNECT request with an authority-form value,
containing the host and port of the
signature parameters (Section 2.3.2) to state target:

CONNECT www.example.com:80 HTTP/1.1
Host: www.example.com

Would result in the algorithm
explicitly, derive following "@request-target" component value:

"@request-target": www.example.com:80

The following OPTIONS request message with the asterisk-form value,
containing a single asterisk "*" character:

OPTIONS * HTTP/1.1
Host: www.example.com

Would result in the algorithm from following "@request-target" component value:

"@request-target": *
If used in a response message, the key material, or use
some pre-configured algorithm agreed upon by "@request-target" component
identifier refers to the signer and
verifier.

* A means associated component value of determining that a given key and algorithm presented in the request are appropriate for
that triggered the request response message being made. For
example, a server expecting only ECDSA signatures should know to
reject any RSA signatures, or a server expecting asymmetric
cryptography should know to reject any symmetric cryptography. signed.

2.3.7. Path

The details of this kind of profiling are "@path" component identifier refers to the purview target path of the
application and outside
HTTP request message. The component value is the scope absolute path of this specification.

2. HTTP Message Signature Covered Content

In order to allow signers
the request target defined by [RFC3986], with no query component and verifiers
no trailing "?" character. The value is normalized according to establish which content the
rules in [SEMANTICS] Section 4.2.3. Namely, an empty path string is
covered by
normalized as a signature, this document defines content identifiers for
data items covered single slash "/" character, and path components are
represented by an HTTP Message Signature as well as the means
for combining these canonicalized their values into a signature input
string.

Some content within HTTP messages can undergo transformations that
change after decoding any percent-encoded
octets. If used, the bitwise value without altering meaning of "@path" component identifier MUST occur only
once in the content (for covered components.

For example, the merging together of header fields with the same name).
Message content must therefore be canonicalized before it is signed,
to ensure that a signature can be verified despite such intermediary
transformations. This document defines rules for each content following request message:

POST /path?param=value HTTP/1.1
Host: www.example.com

Would result in the following "@path" value:

"@path": /path

If used in a response message, the "@path" identifier that transform refers to the identifier's
associated content into
such a canonical form.

Content identifiers are defined using production grammar defined by
RFC8941, Section 4 [RFC8941]. component value of the request that triggered the response
message being signed.

2.3.8. Query

The content "@query" component identifier is an "sf-
string" value. refers to the query component of
the HTTP request message. The content identifier type MAY define parameters
which are included using component value is the "parameters" rule.

content-identifier = sf-string parameters

Note that this means entire
normalized query string defined by [RFC3986], including the leading
"?" character. The value of is normalized according to the rules in
[SEMANTICS] Section 4.2.3. Namely, percent-encoded octets are
decoded. If used, the "@query" component identifier itself is encased MUST occur only
once in
double quotes, with parameters the covered components.

For example, the following as a semicolon-separated
list, such as ""cache-control"", ""date"", or ""@signature-params"". request message:

POST /path?param=value&foo=bar&baz=batman HTTP/1.1
Host: www.example.com

Would result in the following "@query" value:

"@query": ?param=value&foo=bar&baz=batman
The following sections define content request message:

POST /path?queryString HTTP/1.1
Host: www.example.com

Would result in the following "@query" value:

"@query": ?queryString

If used in a response message, the "@query" component identifier types, their
parameters, their
refers to the associated content, and their canonicalization
rules. The method for combining content identifiers into component value of the
signature input request that
triggered the response message being signed.

2.3.9. Query Parameters

If a request target URI uses HTML form parameters in the query string is
as defined in [HTMLURL] Section 2.4.

2.1. HTTP Headers 5, the "@query-params" component
identifier allows addressing of individual query parameters. The content
query parameters MUST be parsed according to [HTMLURL] Section 5.1,
resulting in a list of ("nameString", "valueString") tuples. The
REQUIRED "name" parameter of each input identifier for an HTTP header contains the
"nameString" of a single query parameter. Several different named
query parameters MAY be included in the covered components. Single
named parameters MAY occur in any order in the covered components.

The component value of a single named parameter is the lowercased form the
"valueString" of
its header field name. While HTTP header field names are case-
insensitive, implementations MUST use lowercased field names (e.g.,
"content-type", "date", "etag") when using them as content
identifiers.

Unless overridden the named query parameter defined by additional parameters and rules, [HTMLURL]
Section 5.1, which is the HTTP header
field value MUST be canonicalized after percent-encoded octets are
decoded. Note that this value does not include any leading "?"
characters, equals sign "=", or separating "&" characters. Named
query parameters with the following steps:

1. Create an ordered list of empty "valueString" are included with an
empty string as the field component value.

If a parameter name occurs multiple times in a request, all parameter
values of each instance of
the header field that name MUST be included in the message, separate signature input
lines in the order that they in which the parameters occur (or
will occur) in the message.

2. Strip leading target URI.

For example for the following request:

POST /path?param=value&foo=bar&baz=batman&qux= HTTP/1.1
Host: www.example.com

Indicating the "baz", "qux" and trailing whitespace from each item "param" named query parameters in
would result in the list.

3. Concatenate following "@query-param" value:

"@query-params";name="baz": batman
"@query-params";name="qux":
"@query-params";name="param": value
If used in a response message, the list items together, with "@query-params" component
identifier refers to the associated component value of the request
that triggered the response message being signed.

2.3.10. Status Code

The "@status" component identifier refers to the three-digit numeric
HTTP status code of a comma "," and space "
" between each item. response message as defined in [SEMANTICS]
Section 15. The resulting string component value is the canonicalized value.

2.1.1. Canonicalized Structured serialized three-digit
integer of the HTTP Headers response code, with no descriptive text. If value of
used, the "@status" component identifier MUST occur only once in the
covered components.

For example, the HTTP header following response message:

HTTP/1.1 200 OK
Date: Fri, 26 Mar 2010 00:05:00 GMT

Would result in the following "@status" value:

"@status": 200

The "@status" component identifier MUST NOT be used in a request
message.

2.3.11. Request-Response Signature Binding

When a signed request message results in question is a structured field
([RFC8941]), signed response message,
the content "@request-response" component identifier MAY include can be used to
cryptographically link the "sf" parameter.
If this parameter is included, request and the HTTP header value MUST be
canonicalized using response to each other by
including the rules specified identified request signature value in Section 4 the response's
signature input without copying the value of RFC8941
[RFC8941]. Note that this process will replace any optional
whitespace with the request's signature
to the response directly. This component identifier has a single space.
REQUIRED parameter:

"key" Identifies which signature from the response to sign.

The resulting string component value is used as the field "sf-binary" representation of the
signature value input in Section 2.1.

2.1.2. Canonicalization Examples

This section contains non-normative examples of canonicalized values
for header fields, given the following example HTTP message:

Server: www.example.com referenced request identified by the "key"
parameter.

For example, when serving this signed request:

NOTE: '\' line wrapping per RFC 8792

POST /foo?param=value&pet=dog HTTP/1.1
Host: example.com
Date: Tue, 07 Jun 2014 20:51:35 20 Apr 2021 02:07:55 GMT
X-OWS-Header: Leading and trailing whitespace.
X-Obs-Fold-Header: Obsolete
line folding.
X-Empty-Header:
Cache-Control: max-age=60
Cache-Control: must-revalidate

The
Content-Type: application/json
Content-Length: 18
Signature-Input: sig1=("@authority" "content-type")\
;created=1618884475;keyid="test-key-rsa-pss"
Signature: sig1=:KuhJjsOKCiISnKHh2rln5ZNIrkRvue0DSu5rif3g7ckTbbX7C4\
Jp3bcGmi8zZsFRURSQTcjbHdJtN8ZXlRptLOPGHkUa/3Qov79gBeqvHNUO4bhI27p\
4WzD1bJDG9+6ml3gkrs7rOvMtROObPuc78A95fa4+skS/t2T7OjkfsHAm/enxf1fA\
wkk15xj0n6kmriwZfgUlOqyff0XLwuH4XFvZ+ZTyxYNoo2+EfFg4NVfqtSJch2WDY\
7n/qmhZOzMfyHlggWYFnDpyP27VrzQCQg8rM1Crp6MrwGLa94v6qP8pq0sQVq2DLt\
4NJSoRRqXTvqlWIRnexmcKXjQFVz6YSA==:

{"hello": "world"}

This would result in the following table shows example canonicalized values for header
fields, given that unsigned response message:

{"busy": true, "message": "Your call is very important to us"}

The server signs the response with its own key and trailing whitespace. |
+---------------------+----------------------------------+

Table 1: Non-normative examples of header field
canonicalization.

2.2. Dictionary Structured Field Members

An individual member in includes the value
signature of a Dictionary Structured Field is
identified by using "sig1" from the parameter "key" on request in the content identifier for covered components of the header.
response. The value of signature input string for this parameter example is:

NOTE: '\' line wrapping per RFC 8792

"content-type": application/json
"content-length": 62
"@status": 200
"@request-response";key="sig1": :KuhJjsOKCiISnKHh2rln5ZNIrkRvue0DSu\
5rif3g7ckTbbX7C4Jp3bcGmi8zZsFRURSQTcjbHdJtN8ZXlRptLOPGHkUa/3Qov79\
gBeqvHNUO4bhI27p4WzD1bJDG9+6ml3gkrs7rOvMtROObPuc78A95fa4+skS/t2T7\
OjkfsHAm/enxf1fAwkk15xj0n6kmriwZfgUlOqyff0XLwuH4XFvZ+ZTyxYNoo2+Ef\
Fg4NVfqtSJch2WDY7n/qmhZOzMfyHlggWYFnDpyP27VrzQCQg8rM1Crp6MrwGLa94\
v6qP8pq0sQVq2DLt4NJSoRRqXTvqlWIRnexmcKXjQFVz6YSA==:
"@signature-params": ("content-type" "content-length" "@status" \
"@request-response";key="sig1");created=1618884475\
;keyid="test-key-ecc-p256"

The signed response message is:

NOTE: '\' line wrapping per RFC 8792

HTTP/1.1 200 OK
Date: Tue, 20 Apr 2021 02:07:56 GMT
Content-Type: application/json
Content-Length: 62
Signature-Input: sig1=("content-type" "content-length" "@status" \
"@request-response";key="sig1");created=1618884475\
;keyid="test-key-ecc-p256"
Signature: sig1=:crVqK54rxvdx0j7qnt2RL1oQSf+o21S/6Uk2hyFpoIfOT0q+Hv\
msYAXUXzo0Wn8NFWh/OjWQOXHAQdVnTk87Pw==:

{"busy": true, "message": "Your call is a very important to us"}

Since the key being
identified, without any parameters present on that key request's signature value itself is not repeated in the
original dictionary.

An individual member in
response, the requester MUST keep the original signature value around
long enough to validate the signature of a Dictionary Structured Field is
canonicalized by applying the serialization algorithm described response.

The "@request-response" component identifier MUST NOT be used in
Section 4.1.2 of RFC8941 [RFC8941] on a Dictionary containing only
that member.

2.2.1. Canonicalization Examples

This section contains non-normative examples of canonicalized values
for Dictionary Structured Field Members given
request message.

2.4. Creating the following example
header field, whose value Signature Input String

The signature input is assumed to be a Dictionary:

X-Dictionary: a=1, b=2;x=1;y=2, c=(a b c)

The following table shows example US-ASCII string containing the canonicalized values for different
content identifiers, given that field:

+======================+=====================+
| Content Identifier | Canonicalized Value |
+======================+=====================+
| "x-dictionary";key=a | 1 |
+----------------------+---------------------+
| "x-dictionary";key=b | 2;x=1;y=2 |
+----------------------+---------------------+
| "x-dictionary";key=c | (a, b, c) |
+----------------------+---------------------+

Table 2: Non-normative examples of
Dictionary member canonicalization.

2.3. Specialty Content Fields

Content not found
HTTP message components covered by the signature. To create the
signature input string, the signer or verifier concatenates together
entries for each identifier in an HTTP header can the signature's covered components
(including their parameters) using the following algorithm:

1. Let the output be included an empty string.

2. For each message component item in the signature
base string by defining a content identifier and covered components set (in
order):

1. Append the canonicalization
method component identifier for its content.

To differentiate specialty content identifiers from HTTP headers,
specialty content identifiers MUST start with the "at" "@" character.
This specification defines covered component
serialized according to the following specialty content
identifiers:

@request-target The target request endpoint. "component-identifier" rule.

2. Append a single colon "":""

3. Append a single space "" ""

4. Append the covered component's canonicalized component value,
as defined by the HTTP message component type. (Section 2.3.1)

@signature-params The 2.1
and Section 2.3)

5. Append a single newline ""\\n""

3. Append the signature metadata parameters for this
signature. component (Section 2.3.2)

Additional specialty content identifiers MAY be 2.3.1) as
follows:

1. Append the component identifier for the signature parameters
serialized according to the "component-identifier" rule, i.e.
""@signature-params""

2. Append a single colon "":""

3. Append a single space "" ""

4. Append the signature parameters' canonicalized component
value as defined and
registered in Section 2.3.1

4. Return the HTTP Signatures Specialty Content Identifier
Registry. (Section 5.3)

2.3.1. Request Target

The request target endpoint, consisting of output string.

If covered components reference a component identifier that cannot be
resolved to a component value in the request method and message, the
path and query of implementation MUST
produce an error. Such situations are included but not limited to:

* The signer or verifier does not understand the effective request URI, component
identifier.

* The component identifier identifies a field that is identified by not present in
the
"@request-target" identifier.

Its message or whose value is canonicalized as follows:

1. Take the lowercased HTTP method of malformed.

* The component identifier is a Dictionary member identifier that
references a field that is not present in the message.

2. Append message, is not a space " ".

3. Append
Dictionary Structured Field, or whose value is malformed.

* The component identifier is a Dictionary member identifier that
references a member that is not present in the path field value, or
whose value is malformed. E.g., the identifier is
""x-dictionary";key="c"" and query of the request target value of the message,
formatted according to the rules defined for the :path pseudo- "x-dictionary"
header in [HTTP2], Section 8.1.2.3. The resulting string field is "a=1, b=2"

In the
canonicalized value.

2.3.1.1. Canonicalization Examples

The following table contains non-normative example example, the HTTP messages and
their canonicalized "@request-target" values.

Table 3: Non-normative examples of "@request-target"
canonicalization.

2.3.2. Signature Parameters

HTTP Message Signatures have metadata properties that provide
information regarding the signature's generation and/or verification.

The signature parameters specialty content is identified by the
"@signature-params" identifier.

Its canonicalized value is the serialization of the signature
parameters for this signature, including the covered content list example.org
Date: Tue, 20 Apr 2021 02:07:55 GMT
X-Example: Example header
with all associated parameters.

* "alg": some whitespace.
X-Empty-Header:
Cache-Control: max-age=60
Cache-Control: must-revalidate
The HTTP message signature algorithm from covered components consist of the "@method", "@path", and
"@authority" specialty component identifiers followed by the "Cache-
Control", "X-Empty-Header", "X-Example" HTTP Message
Signature Algorithm Registry, as an "sf-string" value.

* "keyid": headers, in order. The identifier for the key material as an "sf-string"
value.

* "created": Creation time as an "sf-integer" UNIX
signature parameters consist of a creation timestamp value.
Sub-second precision is not supported.

* "expires": Expiration time as an "sf-integer" UNIX timestamp
value. Sub-second precision "1618884475"
and the key identifier is not supported.

* "nonce": A random unique value generated "test-key-rsa-pss". The signature input
string for this signature.

Additional message with these parameters can be defined in the is:

NOTE: '\' line wrapping per RFC 8792

"@method": GET
"@path": /foo
"@authority": example.org
"cache-control": max-age=60, must-revalidate
"x-empty-header":
"x-example": Example header with some whitespace.
"@signature-params": ("@method" "@path" "@authority" \
"cache-control" "x-empty-header" "x-example");created=1618884475\
;keyid="test-key-rsa-pss"

Figure 1: Non-normative example Signature Input

3. HTTP Message Signatures

An HTTP Message Signature Parameters
Registry (Section 5.2.2).

The is a signature parameters are serialized using over a string generated from
a subset of the rules in Section 4 components of RFC8941 [RFC8941] as follows:

1. Let an HTTP message in addition to metadata
about the output be signature itself. When successfully verified against an empty string.

2. Determine
HTTP message, an order for the content identifiers of HTTP Message Signature provides cryptographic proof
that the covered
content. Once this order message is chosen, it cannot be changed.

3. Serialize semantically equivalent to the content identifiers of message for which
the covered content,
including all parameters, as an ordered "inner-list" according signature was generated, with respect to
Section 4.1.1.1 the subset of RFC8941 [RFC8941] and append this message
components that was signed.

3.1. Creating a Signature

In order to create a signature, a signer MUST follow the
output.

4. Determine following
algorithm:

1. The signer chooses an order for any HTTP signature parameters. Once this order algorithm and key material
for signing. The signer MUST choose key material that is chosen, it cannot be changed.

5. Append
appropriate for the parameters signature's algorithm, and that conforms to
any requirements defined by the "inner-list" in algorithm, such as key size or
format. The mechanism by which the chosen order
according to Section 4.1.1.2 signer chooses the algorithm
and key material is out of RFC8941 [RFC8941], skipping
parameters that are not available or not used scope for this signature.

6. document.

2. The output contains signer sets the signature parameters value.

Note that signature's creation time to the "inner-list" serialization is used for current
time.

3. If applicable, the covered
content value instead of signer sets the "sf-list" serialization in order signature's expiration time
property to
facilitate this value's additional inclusion in the "Signature-Input"
header's dictionary, as discussed in Section 4.1.

This example shows a canonicalized value for time at which the parameters of a
given signature:

("@request-target" "host" "date" "cache-control" "x-empty-header" \
"x-example");keyid="test-key-rsa-pss";alg="rsa-pss-sha512";\
created=1618884475;expires=1618884775

Note that signature is to expire.

4. The signer creates an HTTP ordered set of component identifiers
representing the message could contain multiple signatures, but only components to be covered by the
signature, and attaches signature metadata parameters used for the current signature are included
in to this field.

2.4. Creating the Signature Input String
set. The signature input is a US-ASCII string containing the content that serialized value of this is covered by the signature. To create later used as the signature input string, value of
the signer or verifier concatenates together entries for each
identifier "Signature-Input" field as described in Section 4.1.

* Once an order of covered components is chosen, the signature's covered content and parameters using order MUST
NOT change for the following algorithm:

1. Let life of the output signature.

* Each covered component identifier MUST be either an empty string.

2. For each covered content item HTTP field
in the covered content list (in
order):

1. Append the message Section 2.1 or a specialty component identifier for
listed in Section 2.3 or its associated registry.

* Signers of a request SHOULD include some or all of the message
control data in the covered content serialized
according components, such as the "@method",
"@authority", "@target-uri", or some combination thereof.

* Signers SHOULD include the "created" signature metadata
parameter to indicate when the "content-identifier" rule.

2. Append a single colon "":""

3. Append a single space "" ""

4. Append signature was created.

* The "@signature-params" specialty component identifier is not
explicitly listed in the list of covered content's canonicalized value, component
identifiers, because it is required to always be present as defined
by
the covered content type. (Section 2.1 last line in the signature input. This ensures that a
signature always covers its own metadata.

* Further guidance on what to include in this set and Section 2.3) in what
order is out of scope for this document.

5. Append a single newline ""\\n""

3. Append The signer creates the signature parameters input string based on these
signature parameters. (Section 2.3.2) as follows:

1. Append the identifier for 2.4)

6. The signer signs the signature parameters serialized
according to input with the "content-identifier" rule, ""@signature-
params""

2. Append a single colon "":""

3. Append a single space "" ""

4. Append chosen signing
algorithm using the key material chosen by the signer. Several
signing algorithms are defined in in Section 3.3.

7. The byte array output of the signature parameters' canonicalized function is the HTTP
message signature output value to be included in the "Signature"
field as defined in Section 2.3.2

4. Return 4.2.

For example, given the output string.

If covered content references an identifier that cannot be resolved
to a value HTTP message and signature parameters in the message,
example in Section 2.4, the implementation MUST produce an error.
Such situations are included but not limited to:

* The signer or verifier does not understand example signature input string when
signed with the content identifier.

* The identifier identifies a header field that is not present "test-key-rsa-pss" key in Appendix B.1.2 gives the
following message or whose signature output value, encoded in Base64:

NOTE: '\' line wrapping per RFC 8792

P0wLUszWQjoi54udOtydf9IWTfNhy+r53jGFj9XZuP4uKwxyJo1RSHi+oEF1FuX6O29\
d+lbxwwBao1BAgadijW+7O/PyezlTnqAOVPWx9GlyntiCiHzC87qmSQjvu1CFyFuWSj\
dGa3qLYYlNm7pVaJFalQiKWnUaqfT4LyttaXyoyZW84jS8gyarxAiWI97mPXU+OVM64\
+HVBHmnEsS+lTeIsEQo36T3NFf2CujWARPQg53r58RmpZ+J9eKR2CD6IJQvacn5A4Ix\
5BUAVGqlyp8JYm+S/CWJi31PNUjRRCusCVRj05NrxABNFv3r5S9IXf2fYJK+eyW4AiG\
VMvMcOg==

Figure 2: Non-normative example signature value is malformed.

* The identifier is

3.2. Verifying a Dictionary member identifier that references Signature

A verifier processes a
header field that is not present signature and its associated signature input
parameters in concert with each other.

In order to verify a signature, a verifier MUST follow the message, following
algorithm:

1. Parse the "Signature" and "Signature-Input" fields and extract
the signatures to be verified.

1. If there is not a
Dictionary Structured Field, or whose more than one signature value is malformed.

* The identifier is a Dictionary member identifier that references a
member that present, determine
which signature should be processed for this message. If an
applicable signature is not present in found, produce an error.

2. If the chosen "Signature" value does not have a corresponding
"Signature-Input" value, produce an error.

2. Parse the values of the chosen "Signature-Input" field to get the
parameters for the signature to be verified.

3. Parse the header field value, or whose value is malformed. E.g., of the identifier is
""x-dictionary";key="c"" and corresponding "Signature" field to get the
byte array value of the "x-dictionary"
header field is "a=1, b=2"

In signature to be verified.

4. Examine the following non-normative example, signature parameters to confirm that the HTTP signature
meets the requirements described in this document, as well as any
additional requirements defined by the application such as which
message being signed components are required to be covered by the signature.
(Section 3.2.1)

5. Determine the verification key material for this signature. If
the key material is known through external means such as static
configuration or external protocol negotiation, the following request:

GET /foo HTTP/1.1
Host: example.org
Date: Tue, 20 Apr 2021 02:07:55 GMT
X-Example: Example header verifier will
use that. If the key is identified in the signature parameters,
the verifier will dereference this to appropriate key material to
use with some whitespace.
X-Empty-Header:
Cache-Control: max-age=60
Cache-Control: must-revalidate the signature. The covered content consists verifier has to determine the
trustworthiness of the "@request-target" specialty
content followed by key material for the "Host", "Date", "Cache-Control", "X-Empty-
Header", "X-Example" HTTP headers, context in order. The which the
signature creation
timestamp is "1618884475" and the presented. If a key identifier is "test-key-rsa-
pss". The signature input string identified that the verifier
does not know, does not trust for this message with these
parameters is:

"@request-target": get /foo
"host": example.org
"date": Tue, 20 Apr 2021 02:07:55 GMT
"cache-control": max-age=60, must-revalidate
"x-empty-header":
"x-example": Example header with some whitespace.
"@signature-params": ("@request-target" "host" "date" "cache-control" \
"x-empty-header" "x-example");created=1618884475;\
keyid="test-key-rsa-pss"

Figure 1: Non-normative example Signature Input

3. HTTP Message Signatures

An HTTP Message Signature request, or does not match
something preconfigured, the verification MUST fail.

6. Determine the algorithm to apply for verification:

1. If the algorithm is a known through external means such as
static configuration or external protocol negotiation, the
verifier will use this algorithm.

2. If the algorithm is explicitly stated in the signature over
parameters using a string generated value from
a subset of the content in an HTTP message and metadata about Message Signatures
registry, the
signature itself. When successfully verified against verifier will use the referenced algorithm.

3. If the algorithm can be determined from the keying material,
such as through an HTTP
message, it provides cryptographic proof that with respect to algorithm field on the
subset of content that was signed, key value itself,
the message is semantically
equivalent to verifier will use this algorithm.

4. If the message for which algorithm is specified in more that one location, such
as through static configuration and the algorithm signature was generated.

3.1. Creating a Signature

In order to create a signature, a signer MUST follow
parameter, or the following
algorithm:

1. The signer chooses an HTTP signature algorithm signature parameter and from the
key material
for signing. The signer itself, the resolved algorithms MUST choose key material that is
appropriate for be the signature's algorithm,
same. If the algorithms are not the same, the verifier MUST
vail the verification.

7. Use the received HTTP message and that conforms the signature's metadata to
any requirements defined by
recreate the algorithm, such as key size or
format. The mechanism by which signature input, using the signer chooses process described in
Section 2.4. The value of the algorithm
and key material "@signature-params" input is out the
value of scope the "SignatureInput" field for this document.

2. The signer sets the signature's creation time signature serialized
according to the current
time.

3. If applicable, the signer sets rules described in Section 2.3.1, not including
the signature's expiration time
property to label from the time at which "Signature-Input" field.

8. If the signature key material is to expire.

4. The signer creates an ordered list of content identifiers
representing appropriate for the message content and signature metadata algorithm, apply the
verification algorithm to be
covered by the signature, recalculated signature
input, signature parameters, key material, and assigns this list as the
signature's Covered Content.

* Once an order algorithm.
Several algorithms are defined in Section 3.3.

9. The results of covered content is chosen, the order MUST NOT
change for verification algorithm function are the life final
results of the signature.

* Each covered content identifier MUST either reference an HTTP
header in signature verification.

If any of the request message Section 2.1 or reference a
specialty content field listed in Section 2.3 above steps fail or its
associated registry.

* Signers SHOULD include "@request-target" in produce an error, the covered
content list.

* Signers SHOULD include a date stamp signature
validation fails.

3.2.1. Enforcing Application Requirements

The verification requirements specified in some form, such this document are intended
as a baseline set of restrictions that are generally applicable to
all use cases. Applications using the "date" header. Alternatively, the "created"
signature metadata parameter can fulfil HTTP Message Signatures MAY impose
requirements above and beyond those specified by this role. document, as
appropriate for their use case.

Some non-normative examples of additional requirements an application
might define are:

* Further guidance on what to include in this list and in what
order is out Requiring a specific set of scope for this document. However, note that
the list order is significant and once established for header fields to be signed (e.g.,
"Authorization", "Digest").

* Enforcing a given maximum signature it MUST be preserved for that signature. age.

* Note that Prohibition of signature metadata parameters, such as runtime
algorithm signaling with the "@signature-params" specialty identifier is not
explicitly listed in "alg" parameter.

* Prohibiting the list use of covered content identifiers,
because it is required certain algorithms, or mandating the use of
a specific algorithm.

* Requiring keys to always be present as the last line
in the signature input. This ensures that of a signature always
covers its own metadata.

5. The signer creates certain size (e.g., 2048 bits vs. 1024
bits).

* Enforcing uniqueness of a "nonce" value.

Application-specific requirements are expected and encouraged. When
an application defines additional requirements, it MUST enforce them
during the signature input string. (Section 2.4)

6. The signer signs the verification process, and signature input with verification
MUST fail if the chosen signing
algorithm using signature does not conform to the key material chosen by application's
requirements.

Applications MUST enforce the signer. Several
signing algorithms are requirements defined in in Section 3.3.

7. The byte array output this document.
Regardless of the signature function is the use case, applications MUST NOT accept signatures that
do not conform to these requirements.

3.3. Signature Algorithm Methods

HTTP
message Message signatures MAY use any cryptographic digital signature output value to be included in
or MAC method that is appropriate for the "Signature"
header as defined in Section 4.2.

For example, given key material, environment,
and needs of the HTTP message signer and verifier. All signatures are generated
from and signature parameters in verified against the
example in Section 2.4, byte values of the example signature input
string when
signed with the "test-key-rsa-pss" key in Appendix B.1.2 gives the
following message signature output value, encoded defined in Base64:

lPxkxqDEPhgrx1yPaKLO7eJ+oPjSwsQ5NjWNRfYP7Jw0FwnK1k8/GH7g5s2q0VTTKVm\
xyfpUDp/HsDphh5Z7Fa/lvtujHyFe/0EP9z7bnVb7YBZrxV52LGvP8p4APhOYuG4yaH\
z478GsJav9BQYK0B2IOHdLFJe8qwWPJs07J47gPewpNwCt0To/zZ2KPpylGX5UHVgJP\
Uom64KjX43u2OwIvSoPEYk4nuBvLR9yxYAHURaTfLoEDUCtY1FsU1hOfG3jAlcT6ill\
fnyS72PEdSSzw1KsxroMj9IYpFhva77YxmJRk4pCIW0F0Kj0ukl7J4y2aZJHMCYI3g8\
yfqh/wQ==

Figure 2: Non-normative example signature value

3.2. Verifying a Signature

A verifier processes a Section 2.4.

Each signature and algorithm method takes as its associated input the signature
input
parameters in concert with each other.

In order to verify a signature, string as a verifier MUST follow the following
algorithm:

1. Parse set of byte values ("I"), the "Signature" and "Signature-Input" headers signing key material
("Ks"), and extract outputs the signatures to be verified.

1. If there is more than one signature value present, determine
which signature should be processed for this request. If an
appropriate signature is not found, produce an error.

2. If the chosen "Signature" value does not have output as a corresponding
"Signature-Input" value, produce an error.

2. Parse the values set of byte values
("S"):

HTTP_SIGN (I, Ks) -> S

Each verification algorithm method takes as its input the chosen "Signature-Input" header field to
get the parameters for the
recalculated signature to be verified.

3. Parse the value input string as a set of the corresponding "Signature" header field to
get the byte array value of values ("I"),
the signature to be verified.

4. Examine verification key material ("Kv"), and the presented signature parameters to confirm that the signature
meets the requirements described in this document, as well
be verified as any
additional requirements defined by a set of byte values ("S") and outputs the application such
verification result ("V") as which
contents are required a boolean:

HTTP_VERIFY (I, Kv, S) -> V

This section contains several common algorithm methods. The method
to use can be covered by communicated through the signature.
(Section 3.2.1)

5. Determine algorithm signature parameter
defined in Section 2.3.1, by reference to the verification key material for material, or
through mutual agreement between the signer and verifier.

3.3.1. RSASSA-PSS using SHA-512

To sign using this signature. If algorithm, the key material is known through external means such as static
configuration or external protocol negotiation, signer applies the verifier will
use that. If "RSASSA-PSS-SIGN
(K, M)" function [RFC8017] with the signer's private signing key is identified in
("K") and the signature parameters,
the verifier will dereference this to appropriate key material to
use input string ("M") (Section 2.4). The mask
generation function is "MGF1" as specified in [RFC8017] with the signature. a hash
function of SHA-512 [RFC6234]. The verifier has salt length ("sLen") is 64 bytes.
The hash function ("Hash") SHA-512 [RFC6234] is applied to determine the
trustworthiness of the key material for
signature input string to create the context in digest content to which the
digital signature is presented. If a key applied. The resulting signed content byte
array ("S") is identified that the verifier
does not know, does not trust for HTTP message signature output used in Section 3.1.

To verify using this request, or does not match
something preconfigured, algorithm, the verification MUST fail.

6. Determine verifier applies the algorithm to apply for verification:

1. If "RSASSA-PSS-
VERIFY ((n, e), M, S)" function [RFC8017] using the algorithm is known through external means such as
static configuration or external protocol negotiation, public key
portion of the
verifier will use this algorithm.

2. If verification key material ("(n, e)") and the algorithm signature
input string ("M") re-created as described in Section 3.2. The mask
generation function is explicitly stated "MGF1" as specified in [RFC8017] with a hash
function of SHA-512 [RFC6234]. The salt length ("sLen") is 64 bytes.
The hash function ("Hash") SHA-512 [RFC6234] is applied to the
signature
parameters using a value from input string to create the HTTP Message Signatures
registry, digest content to which the
verification function is applied. The verifier will use the referenced algorithm.

3. If extracts the algorithm can HTTP
message signature to be determined from the keying material,
such verified ("S") as through an algorithm field on described in Section 3.2.
The results of the key value itself, verification function are compared to the verifier will use this algorithm.

4. If http
message signature to determine if the algorithm signature presented is specified in more that one location, such
as through static configuration and valid.

3.3.2. RSASSA-PKCS1-v1_5 using SHA-256

To sign using this algorithm, the algorithm signature
parameter, or signer applies the algorithm signature parameter and from "RSASSA-
PKCS1-V1_5-SIGN (K, M)" function [RFC8017] with the signer's private
signing key material itself, ("K") and the resolved algorithms MUST be signature input string ("M") (Section 2.4).
The hash SHA-256 [RFC6234] is applied to the
same. If signature input string
to create the algorithms are not digest content to which the same, digital signature is
applied. The resulting signed content byte array ("S") is the HTTP
message signature output used in Section 3.1.

To verify using this algorithm, the verifier MUST
vail applies the verification.

7. Use "RSASSA-
PKCS1-V1_5-VERIFY ((n, e), M, S)" function [RFC8017] using the received HTTP message public
key portion of the verification key material ("(n, e)") and the signature's metadata to
recreate the
signature input, using the process input string ("M") re-created as described in Section 2.4. 3.2.
The value of the "@signature-params" input hash function SHA-256 [RFC6234] is applied to the
value of the SignatureInput header field for this signature
serialized according input
string to create the rules described in Section 2.3.2, not
including the signature's label from the "Signature-Input"
header.

8. If the key material is appropriate for the algorithm, apply digest content to which the verification algorithm to
function is applied. The verifier extracts the signature, recalculated signature
input, HTTP message
signature parameters, key material, and algorithm.
Several algorithms are defined to be verified ("S") as described in Section 3.3.

9. 3.2. The
results of the verification algorithm function are compared to the final
results of the signature verification.

If any of the above steps fail, the http message
signature validation fails.

3.2.1. Enforcing Application Requirements

The verification requirements specified in this document are intended
as a baseline set of restrictions that are generally applicable to
all use cases. Applications using HTTP Message Signatures MAY impose
requirements above and beyond those specified by this document, as
appropriate for their use case.

Some non-normative examples of additional requirements an application
might define are:

* Requiring a specific set of header fields to be signed (e.g.,
Authorization, Digest).

* Enforcing a maximum signature age.

* Prohibiting the use of certain algorithms, or mandating determine if the use of
an algorithm.

* Requiring keys to be of a certain size (e.g., 2048 bits vs. 1024
bits).

* Enforcing uniqueness of a nonce value.

Application-specific requirements are expected and encouraged. When
an application defines additional requirements, it MUST enforce them
during signature presented is valid.

3.3.3. HMAC using SHA-256

To sign and verify using this algorithm, the signature verification process, signer applies the
"HMAC" function [RFC2104] with the shared signing key ("K") and the
signature verification
MUST fail if input string ("text") (Section 2.4). The hash function
SHA-256 [RFC6234] is applied to the signature does not conform input string to create
the digest content to which the application's
requirements.

Applications MUST enforce HMAC is applied, giving the requirements defined signature
result.

For signing, the resulting value is the HTTP message signature output
used in this document.
Regardless of use case, applications MUST NOT accept signatures that
do not conform to these requirements.

3.3. Signature Algorithm Methods Section 3.1.

For verification, the verifier extracts the HTTP Message signatures MAY use any cryptographic digital message signature
or MAC method that to
be verified ("S") as described in Section 3.2. The output of the
HMAC function is appropriate for compared to the key material, environment, value of the HTTP message signature,
and needs the results of the signer comparison determine the validity of the
signature presented.

3.3.4. ECDSA using curve P-256 DSS and verifier. All signatures are generated
from SHA-256

To sign using this algorithm, the signer applies the "ECDSA"
algorithm [FIPS186-4] using curve P-256 with the signer's private
signing key and verified against the byte values of signature input string (Section 2.4). The hash
SHA-256 [RFC6234] is applied to the signature input string defined to create
the digest content to which the digital signature is applied. The
resulting signed content byte array is the HTTP message signature
output used in Section 2.4.

Each signature 3.1.

To verify using this algorithm, the verifier applies the "ECDSA"
algorithm method takes as its input [FIPS186-4] using the signature
input string as a set public key portion of byte values ("I"), the signing
verification key material
("Ks"), and outputs the signed content as a set of byte values ("S"):

HTTP_SIGN (I, Ks) -> S

Each verification algorithm method takes as its signature input string re-created
as described in Section 3.2. The hash function SHA-256 [RFC6234] is
applied to the
recalculated signature input string as a set of byte values ("I"), to create the digest content to
which the verification key material ("Kv"), and function is applied. The verifier extracts
the presented HTTP message signature to be verified ("S") as a set described in
Section 3.2. The results of byte values ("S") and outputs the verification result ("V") as a boolean:

HTTP_VERIFY (I, Kv, S) -> V

This section contains several common algorithm methods. The method function are compared
to use can be communicated through the algorithm http message signature parameter
defined in Section 2.3.2, by reference to determine if the key material, or
through mutual agreement between signature presented
is valid.

3.3.5. JSON Web Signature (JWS) algorithms

If the signer and verifier.

3.3.1. RSASSA-PSS using SHA-512

To sign using this algorithm, signing algorithm is a JOSE signing algorithm from the signer applies JSON
Web Signature and Encryption Algorithms Registry established by
[RFC7518], the "RSASSA-PSS-SIGN
(K, M)" function [RFC8017] with JWS algorithm definition determines the signer's private signature and
hashing algorithms to apply for both signing key
("K") and the signature input string ("M") (Section 2.4). The mask
generation function verification. There
is "MGF1" as specified in [RFC8017] with a hash
function no use of SHA-512 [RFC6234]. The salt length ("sLen") the explicit "alg" signature parameter when using JOSE
signing algorithms.

For both signing and verification, the HTTP messages signature input
string (Section 2.4) is 64 bytes. used as the entire "JWS Signing Input". The hash function ("Hash") SHA-512 [RFC6234]
JOSE Header defined in [RFC7517] is applied to not used, and the signature input
string to create is not first encoded in Base64 before applying the digest content to which algorithm.
The output of the
digital JWS signature is applied. The resulting signed content taken as a byte array ("S") is prior to the
Base64url encoding used in JOSE.

The JWS algorithm MUST NOT be "none" and MUST NOT be any algorithm
with a JOSE Implementation Requirement of "Prohibited".

4. Including a Message Signature in a Message

Message signatures can be included within an HTTP message via the
"Signature-Input" and "Signature" HTTP fields, both defined within
this specification. When attached to a message, an HTTP message
signature output is identified by a label. This label MUST be unique within
a given HTTP message and MUST be used in Section 3.1.

To verify using this algorithm, both the verifier applies "Signature-Input"
and "Signature". The label is chosen by the "RSASSA-PSS-
VERIFY ((n, e), M, S)" function [RFC8017] using signer, except where a
specific label is dictated by protocol negotiations.

An HTTP message signature MUST use both fields containing the public key
portion of same
labels: the verification key material ("(n, e)") "Signature" HTTP field contains the signature value,
while the "Signature-Input" HTTP field identifies the covered
components and parameters that describe how the signature
input string ("M") re-created as described in Section 3.2. The mask
generation function is "MGF1" as specified in [RFC8017] with a hash
function of SHA-512 [RFC6234]. was
generated. Each field contains labeled values and MAY contain
multiple labeled values, where the labels determine the correlation
between the "Signature" and "Signature-Input" fields.

4.1. The salt length ("sLen") is 64 bytes. 'Signature-Input' HTTP Field

The hash function ("Hash") SHA-512 [RFC6234] "Signature-Input" HTTP field is applied to the
signature input string to create a Dictionary Structured Field
[RFC8941] containing the digest content to which metadata for one or more message signatures
generated from components within the
verification function is applied. HTTP message. Each member
describes a single message signature. The verifier extracts member's name is an
identifier that uniquely identifies the HTTP message signature to be verified ("S") as described in Section 3.2.
The results within the
context of the verification function are compared to HTTP message. The member's value is the http
message signature to determine if serialization
of the covered components including all signature presented is valid.

3.3.2. RSASSA-PKCS1-v1_5 using SHA-256

To sign metadata
parameters, using this algorithm, the signer applies serialization process defined in Section 2.3.1.

NOTE: '\' line wrapping per RFC 8792

Signature-Input: sig1=("@method" "@target-uri" "host" "date" \
"cache-control" "x-empty-header" "x-example");created=1618884475\
;keyid="test-key-rsa-pss"

To facilitate signature validation, the "RSASSA-
PKCS1-V1_5-SIGN (K, M)" function [RFC8017] with "Signature-Input" field value
MUST contain the signer's private
signing key ("K") and same serialized value used in generating the
signature input string ("M") (Section 2.4). string's "@signature-params" value.

The hash SHA-256 [RFC6234] is applied to signer MAY include the signature input string "Signature-Input" field as a trailer to create the digest
facilitate signing a message after its content has been processed by
the signer. However, since intermediaries are allowed to which drop
trailers as per [SEMANTICS], it is RECOMMENDED that the digital "Signature-
Input" HTTP field be included only as a header to avoid signatures
being inadvertently stripped from a message.

Multiple "Signature-Input" fields MAY be included in a single HTTP
message. The signature is
applied. labels MUST be unique across all field
values.

4.2. The resulting signed content byte array ("S") 'Signature' HTTP Field

The "Signature" HTTP field is a Dictionary Structured field [RFC8941]
containing one or more message signatures generated from components
within the HTTP
message message. Each member's name is a signature output used
identifier that is present as a member name in Section 3.1.

To verify using this algorithm, the verifier applies the "RSASSA-
PKCS1-V1_5-VERIFY ((n, e), M, S)" function [RFC8017] using "Signature-Input"
Structured field within the public
key portion of HTTP message. Each member's value is a
Byte Sequence containing the verification key material ("(n, e)") and signature value for the message
signature input string ("M") re-created as described identified by the member name. Any member in Section 3.2. the
"Signature" HTTP field that does not have a corresponding member in
the HTTP message's "Signature-Input" HTTP field MUST be ignored.

NOTE: '\' line wrapping per RFC 8792

Signature: sig1=:P0wLUszWQjoi54udOtydf9IWTfNhy+r53jGFj9XZuP4uKwxyJo\
1RSHi+oEF1FuX6O29d+lbxwwBao1BAgadijW+7O/PyezlTnqAOVPWx9GlyntiCiHz\
C87qmSQjvu1CFyFuWSjdGa3qLYYlNm7pVaJFalQiKWnUaqfT4LyttaXyoyZW84jS8\
gyarxAiWI97mPXU+OVM64+HVBHmnEsS+lTeIsEQo36T3NFf2CujWARPQg53r58Rmp\
Z+J9eKR2CD6IJQvacn5A4Ix5BUAVGqlyp8JYm+S/CWJi31PNUjRRCusCVRj05NrxA\
BNFv3r5S9IXf2fYJK+eyW4AiGVMvMcOg==:

The hash function SHA-256 [RFC6234] is applied to signer MAY include the signature input
string "Signature" field as a trailer to create the digest
facilitate signing a message after its content to which has been processed by
the verification
function signer. However, since intermediaries are allowed to drop
trailers as per [SEMANTICS], it is applied. The verifier extracts RECOMMENDED that the "Signature-
Input" HTTP message
signature to field be verified ("S") included only as described a header to avoid signatures
being inadvertently stripped from a message.

Multiple "Signature" fields MAY be included in Section 3.2. a single HTTP message.
The
results of the verification function are compared to the http message signature labels MUST be unique across all field values.

4.3. Multiple Signatures

Multiple distinct signatures MAY be included in a single message.
Since "Signature-Input" and "Signature" are both defined as
Dictionary Structured fields, they can be used to determine if include multiple
signatures within the signature presented is valid.

3.3.3. HMAC using SHA-256

To sign and verify same HTTP message by using this algorithm, the distinct signature
labels. For example, a signer applies the
"HMAC" function [RFC2104] with the shared may include multiple signatures
signing key ("K") and the
signature input string ("text") (Section 2.4). The hash function
SHA-256 [RFC6234] is applied same message components with different keys or algorithms
to support verifiers with different capabilities, or a reverse proxy
may include information about the signature input string to create client in fields when forwarding
the digest content request to which the HMAC is applied, giving the signature
result.

For signing, the resulting value is the HTTP message a service host, including a signature output
used in Section 3.1.

For verification, the verifier extracts over the HTTP message
client's original signature to
be verified ("S") as described in Section 3.2. values.

The output of the
HMAC function following is compared a non-normative example of header fields a reverse
proxy sets in addition to the value of examples in the HTTP message signature,
and previous sections.

NOTE: '\' line wrapping per RFC 8792

Forwarded: for=192.0.2.123
Signature-Input: sig1=("@method" "@path" "@authority" \
"cache-control" "x-empty-header" "x-example")\
;created=1618884475;keyid="test-key-rsa-pss"
Signature: sig1=:P0wLUszWQjoi54udOtydf9IWTfNhy+r53jGFj9XZuP4uKwxyJo\
1RSHi+oEF1FuX6O29d+lbxwwBao1BAgadijW+7O/PyezlTnqAOVPWx9GlyntiCi\
HzC87qmSQjvu1CFyFuWSjdGa3qLYYlNm7pVaJFalQiKWnUaqfT4LyttaXyoyZW8\
4jS8gyarxAiWI97mPXU+OVM64+HVBHmnEsS+lTeIsEQo36T3NFf2CujWARPQg53\
r58RmpZ+J9eKR2CD6IJQvacn5A4Ix5BUAVGqlyp8JYm+S/CWJi31PNUjRRCusCV\
Rj05NrxABNFv3r5S9IXf2fYJK+eyW4AiGVMvMcOg==:

The client's request includes a signature value under the results of label
"sig1", which the comparison determine proxy signs in addition to the validity of "Forwarded" header
defined in [RFC7239]. Note that since the client's signature presented.

3.3.4. ECDSA using curve P-256 DSS and SHA-256

To sign using this algorithm, the signer applies already
covers the "ECDSA"
algorithm [FIPS186-4] using curve P-256 with client's "Signature-Input" value for "sig1", this value is
transitively covered by the signer's private
signing key proxy's signature and the need not be added
explicitly. This results in a signature input string (Section 2.4). The hash
SHA-256 [RFC6234] is applied of:

NOTE: '\' line wrapping per RFC 8792

"signature";key="sig1": :P0wLUszWQjoi54udOtydf9IWTfNhy+r53jGFj9XZuP\
4uKwxyJo1RSHi+oEF1FuX6O29d+lbxwwBao1BAgadijW+7O/PyezlTnqAOVPWx9Gl\
yntiCiHzC87qmSQjvu1CFyFuWSjdGa3qLYYlNm7pVaJFalQiKWnUaqfT4LyttaXyo\
yZW84jS8gyarxAiWI97mPXU+OVM64+HVBHmnEsS+lTeIsEQo36T3NFf2CujWARPQg\
53r58RmpZ+J9eKR2CD6IJQvacn5A4Ix5BUAVGqlyp8JYm+S/CWJi31PNUjRRCusCV\
Rj05NrxABNFv3r5S9IXf2fYJK+eyW4AiGVMvMcOg==:
"forwarded": for=192.0.2.123
"@signature-params": ("signature";key="sig1" "forwarded")\
;created=1618884480;keyid="test-key-rsa";alg="rsa-v1_5-sha256"

And a signature output value of:

NOTE: '\' line wrapping per RFC 8792

cjGvZwbsq9JwexP9TIvdLiivxqLINwp/ybAc19KOSQuLvtmMt3EnZxNiE+797dXK2cj\
PPUFqoZxO8WWx1SnKhAU9SiXBr99NTXRmA1qGBjqus/1Yxwr8keB8xzFt4inv3J3zP0\
k6TlLkRJstkVnNjuhRIUA/ZQCo8jDYAl4zWJJjppy6Gd1XSg03iUa0sju1yj6rcKbMA\
BBuzhUz4G0u1hZkIGbQprCnk/FOsqZHpwaWvY8P3hmcDHkNaavcokmq+3EBDCQTzgwL\
qfDmV0vLCXtDda6CNO2Zyum/pMGboCnQn/VkQ+j8kSydKoFg6EbVuGbrQijth6I0dDX\
2/HYcJg==

These values are added to the HTTP request message by the proxy. The
original signature input string to create is included under the digest content to which identifier "sig1", and the digital
reverse proxy's signature is applied. included under the label "proxy_sig".
The
resulting signed content byte array is proxy uses the HTTP message key "test-key-rsa" to create its signature
output used in Section 3.1.

To verify using this algorithm,
the verifier applies "rsa-v1_5-sha256" signature algorithm, while the "ECDSA"
algorithm [FIPS186-4] client's
original signature was made using the public key portion id of the
verification key material "test-key-rsa-pss"
and the an RSA PSS signature input string re-created
as described in Section 3.2. algorithm.

NOTE: '\' line wrapping per RFC 8792

Forwarded: for=192.0.2.123
Signature-Input: sig1=("@method" "@path" "@authority" \
"cache-control" "x-empty-header" "x-example")\
;created=1618884475;keyid="test-key-rsa-pss", \
proxy_sig=("signature";key="sig1" "forwarded")\
;created=1618884480;keyid="test-key-rsa";alg="rsa-v1_5-sha256"
Signature: sig1=:P0wLUszWQjoi54udOtydf9IWTfNhy+r53jGFj9XZuP4uKwxyJo\
1RSHi+oEF1FuX6O29d+lbxwwBao1BAgadijW+7O/PyezlTnqAOVPWx9GlyntiCi\
HzC87qmSQjvu1CFyFuWSjdGa3qLYYlNm7pVaJFalQiKWnUaqfT4LyttaXyoyZW8\
4jS8gyarxAiWI97mPXU+OVM64+HVBHmnEsS+lTeIsEQo36T3NFf2CujWARPQg53\
r58RmpZ+J9eKR2CD6IJQvacn5A4Ix5BUAVGqlyp8JYm+S/CWJi31PNUjRRCusCV\
Rj05NrxABNFv3r5S9IXf2fYJK+eyW4AiGVMvMcOg==:, \
proxy_sig=:cjGvZwbsq9JwexP9TIvdLiivxqLINwp/ybAc19KOSQuLvtmMt3EnZx\
NiE+797dXK2cjPPUFqoZxO8WWx1SnKhAU9SiXBr99NTXRmA1qGBjqus/1Yxwr8k\
eB8xzFt4inv3J3zP0k6TlLkRJstkVnNjuhRIUA/ZQCo8jDYAl4zWJJjppy6Gd1X\
Sg03iUa0sju1yj6rcKbMABBuzhUz4G0u1hZkIGbQprCnk/FOsqZHpwaWvY8P3hm\
cDHkNaavcokmq+3EBDCQTzgwLqfDmV0vLCXtDda6CNO2Zyum/pMGboCnQn/VkQ+\
j8kSydKoFg6EbVuGbrQijth6I0dDX2/HYcJg==:

The hash function SHA-256 [RFC6234] is
applied to the proxy's signature input string to create the digest content to
which the verification function is applied. The verifier extracts and the HTTP message client's original signature to can be
verified ("S") as described in
Section 3.2. The results of independently for the verification function are compared
to same message, based on the http message signature to determine if needs of
the application. Since the proxy's signature presented
is valid.

3.3.5. JSON Web Signature (JWS) algorithms

If covers the signing algorithm is a JOSE signing algorithm from client
signature, the JSON
Web Signature and Encryption Algorithms Registry established backend service fronted by
[RFC7518], the JWS algorithm definition determines proxy can trust that
the signature and
hashing algorithms proxy has validated the incoming signature.

5. Requesting Signatures

While a signer is free to attach a signature to apply for both signing and verification. There a request or response
without prompting, it is no use of the explicit "alg" often desirable for a potential verifier to
signal that it expects a signature parameter when from a potential signer using JOSE
signing algorithms.

For both signing and verification, the HTTP messages
"Accept-Signature" field.

The message to which the requested signature input
string (Section 2.4) is used applied is known as
the entire "JWS Signing Input". The
JOSE Header defined in [RFC7517] is not used, and "target message". When the signature input
string "Accept-Signature" field is not first encoded sent in Base64 before applying
an HTTP Request message, the algorithm.
The output of field indicates that the JWS signature is taken as a byte array prior client desires
the server to sign the
Base64url encoding used in JOSE.

The JWS algorithm MUST NOT be "none" response using the identified parameters and MUST NOT
the target message is the response to this request. All responses
from resources that support such signature negotiation SHOULD either
be any algorithm uncacheable or contain a "Vary" header field that lists "Accept-
Signature", in order to prevent a cache from returning a response
with a JOSE Implementation Requirement of "Prohibited".

4. Including signature intended for a Message Signature different request.

When the "Accept-Signature" field is used in a Message

Message signatures can be included within an HTTP message via Response
message, the
"Signature-Input" field indicates that the server desires the client to
sign its next request to the server with the identified parameters,
and "Signature" HTTP header fields, both defined
within this specification.

An HTTP the target message signature MUST use both headers: is the "Signature" HTTP
header client's next request. The client can
choose to also continue signing future requests to the same server in
the same way.

The target message of an "Accept-Signature" field contains MUST include all
labeled signatures indicated in the signature value, while "Accept-Header" signature, each
covering the "Signature-
Input" HTTP header field identifies same identified components of the covered content and
parameters "Accept-Signature"
field.

The sender of an "Accept-Signature" field MUST include identifiers
that describe how are appropriate for the signature was generated. Each
header MAY contain multiple labeled values, where type of the labels
determine target message. For
example, if the correlation between target message is a response, the "Signature" and "Signature-
Input" fields.

4.1. identifiers can not
include the "@status" identifier.

5.1. The 'Signature-Input' HTTP Header Accept-Signature Field

The "Signature-Input" "Accept-Signature" HTTP header field is a Dictionary Structured
Header
field [RFC8941] containing the metadata for one or more requested
message signatures to be generated from content within message components of the
target HTTP message. Each member describes a single message
signature. The member's name is an identifier that uniquely
identifies the requested message signature within the context of the
target HTTP message. The member's value is the serialization of the
desired covered content components of the target message, including all any
allowed signature metadata parameters, using the serialization
process defined in Section 2.3.2.

Signature-Input: sig1=("@request-target" 2.3.1.

NOTE: '\' line wrapping per RFC 8792

Accept-Signature: sig1=("@method" "@target-uri" "host" "date" \
"cache-control" "x-empty-header" "x-example");created=1618884475\ "x-example")\
;keyid="test-key-rsa-pss"

To facilitate signature validation, the "Signature-Input" header
value MUST contain the same serialized value used in generating the
signature input string's "@signature-params" value.

4.2. The 'Signature' HTTP Header

The "Signature" HTTP header field is a Dictionary Structured Header
[RFC8941] containing one or more message signatures generated from
content within the HTTP message. Each member's name is a signature
identifier that is present as a member name in the "Signature-Input"
Structured Header within the HTTP message. Each member's value is a
Byte Sequence containing the signature value for the message
signature identified by the member name. Any member in the
"Signature" HTTP header field that does not have a corresponding
member in the HTTP message's "Signature-Input" HTTP header field MUST
be ignored.

Signature: sig1=:lPxkxqDEPhgrx1yPaKLO7eJ+oPjSwsQ5NjWNRfYP7Jw0FwnK1k\
8/GH7g5s2q0VTTKVmxyfpUDp/HsDphh5Z7Fa/lvtujHyFe/0EP9z7bnVb7YBZrxV5\
2LGvP8p4APhOYuG4yaHz478GsJav9BQYK0B2IOHdLFJe8qwWPJs07J47gPewpNwCt\
0To/zZ2KPpylGX5UHVgJPUom64KjX43u2OwIvSoPEYk4nuBvLR9yxYAHURaTfLoED\
UCtY1FsU1hOfG3jAlcT6illfnyS72PEdSSzw1KsxroMj9IYpFhva77YxmJRk4pCIW\
0F0Kj0ukl7J4y2aZJHMCYI3g8yfqh/wQ==:

4.3. Multiple Signatures

Since "Signature-Input" and "Signature" are both defined as
Dictionary Structured Headers, they can be used to include multiple
signatures within the same HTTP message. For example, a signer may

The requested signature MAY include multiple signatures signing the same content with different
keys or algorithms to support verifiers with different capabilities,
or parameters, such as a reverse proxy may desired
algorithm or key identifier. These parameters MUST NOT include information about the client in header
fields when forwarding
parameters that the request signer is expected to a service host, generate, including a
signature over those fields and the client's original signature.
"created" and "nonce" parameters.

5.2. Processing an Accept-Signature

The following is a non-normative example receiver of an "Accept-Signature" field fulfills that header fields a reverse
proxy sets in addition to as
follows:

1. Parse the examples in field value as a Dictionary
2. For each member of the previous sections. dictionary:

1. The
original signature is included under the identifier "sig1", and name of the
reverse proxy's signature member is included under "proxy_sig". The proxy
uses the key "rsa-test-key" to create its signature using label of the "rsa-
v1_5-sha256" output signature value. This results
as specified in a signature input
string of:

"signature";key="sig1": \
:lPxkxqDEPhgrx1yPaKLO7eJ+oPjSwsQ5NjWNRfYP7Jw0FwnK1k8/GH7g5s2q0VTT\
KVmxyfpUDp/HsDphh5Z7Fa/lvtujHyFe/0EP9z7bnVb7YBZrxV52LGvP8p4APhOYu\
G4yaHz478GsJav9BQYK0B2IOHdLFJe8qwWPJs07J47gPewpNwCt0To/zZ2KPpylGX\
5UHVgJPUom64KjX43u2OwIvSoPEYk4nuBvLR9yxYAHURaTfLoEDUCtY1FsU1hOfG3\
jAlcT6illfnyS72PEdSSzw1KsxroMj9IYpFhva77YxmJRk4pCIW0F0Kj0ukl7J4y2\
aZJHMCYI3g8yfqh/wQ==:
"x-forwarded-for": 192.0.2.123
"@signature-params": ("signature";key="sig1" "x-forwarded-for")\
;created=1618884480;keyid="test-key-rsa";alg="rsa-v1_5-sha256"

And a signature output Section 4.1

2. Parse the value of:

XD1O/vEh772WVpY7jYvReXop2+b7xTIIPKH8/OCYzPn78Wd9jodCwAJPF5TYCn9L6n6\
8j4EjGsqFOMkVLVdSQEZqMLjEbvMEdIe8m1a0CLd5kydeaAwoHoglqod6ijkwhhEtxt\
aD8tDZmihQw2mZEH8u4aMSnRntqy7ExCNld0JLharsHV0iCbRO9jIP+d2ApD7gB+eZp\
n3pIvvVJZlxTwPkahFpxKlQtNMPaSqa1lvejURx+ST8CEuz4sS+G/oLJiX3MZenuUoO\
R8HeOHDnjN/VLzrEN4x44iF7WIL+iY2PtK87LUWRAsJAX9GqHL/upsGh1nxIdoVaoLV\
V5w+fRw==

These values are added of the member to obtain the HTTP request message by set of covered
component identifiers

3. Process the proxy. The
different signature values are wrapped onto separate lines requested parameters, such as the signing
algorithm and key material. If any requested parameters
cannot be fulfilled, or if the requested parameters conflict
with those deemed appropriate to
increase human-readability of the result.

X-Forwarded-For: 192.0.2.123
Signature-Input: sig1=("@request-target" "host" "date" \
"cache-control" "x-empty-header" "x-example")\
;created=1618884475;keyid="test-key-rsa-pss", \
proxy_sig=("signature";key="sig1" "x-forwarded-for")\
;created=1618884480;keyid="test-key-rsa";alg="rsa-v1_5-sha256"
Signature: sig1=:lPxkxqDEPhgrx1yPaKLO7eJ+oPjSwsQ5NjWNRfYP7Jw0FwnK1k\
8/GH7g5s2q0VTTKVmxyfpUDp/HsDphh5Z7Fa/lvtujHyFe/0EP9z7bnVb7YBZrx\
V52LGvP8p4APhOYuG4yaHz478GsJav9BQYK0B2IOHdLFJe8qwWPJs07J47gPewp\
NwCt0To/zZ2KPpylGX5UHVgJPUom64KjX43u2OwIvSoPEYk4nuBvLR9yxYAHURa\
TfLoEDUCtY1FsU1hOfG3jAlcT6illfnyS72PEdSSzw1KsxroMj9IYpFhva77Yxm\
JRk4pCIW0F0Kj0ukl7J4y2aZJHMCYI3g8yfqh/wQ==:, \
proxy_sig=:XD1O/vEh772WVpY7jYvReXop2+b7xTIIPKH8/OCYzPn78Wd9jodCwA\
JPF5TYCn9L6n68j4EjGsqFOMkVLVdSQEZqMLjEbvMEdIe8m1a0CLd5kydeaAwoH\
oglqod6ijkwhhEtxtaD8tDZmihQw2mZEH8u4aMSnRntqy7ExCNld0JLharsHV0i\
CbRO9jIP+d2ApD7gB+eZpn3pIvvVJZlxTwPkahFpxKlQtNMPaSqa1lvejURx+ST\
8CEuz4sS+G/oLJiX3MZenuUoOR8HeOHDnjN/VLzrEN4x44iF7WIL+iY2PtK87LU\
WRAsJAX9GqHL/upsGh1nxIdoVaoLVV5w+fRw==:

The proxy's target message, the
process fails and returns an error.

4. Select any additional parameters necessary for completing the
signature

5. Create the "Signature-Input" and "Signature" header values
and associate them with the label

3. Optionally create any additional "Signature-Input" and
"Signature" values, with unique labels not found in the "Accept-
Signature" field

4. Combine all labeled "Signature-Input" and "Signature" values and
attach both headers to the client's original target message

Note that by this process, a signature can be
verified independently for applied to a target message
MUST have the same message, depending on label, MUST have the needs same set of covered
component, and MAY have additional parameters. Also note that the application.

5.
target message MAY include additional signatures not specified by the
"Accept-Signature" field.

6. IANA Considerations

5.1.

6.1. HTTP Signature Algorithms Registry

This document defines HTTP Signature Algorithms, for which IANA is
asked to create and maintain a new registry titled "HTTP Signature
Algorithms". Initial values for this registry are given in
Section 5.1.2. 6.1.2. Future assignments and modifications to existing
assignment are to be made through the Expert Review registration
policy [RFC8126] and shall follow the template presented in
Section 5.1.1. 6.1.1.

Algorithms referenced by algorithm identifiers have to be fully
defined with all parameters fixed. Algorithm identifiers in this
registry are to be interpreted as whole string values and not as a
combination of parts. That is to say, it is expected that
implementors understand "rsa-pss-sha512" as referring to one specific
algorithm with its hash, mask, and salt values set as defined here.
Implementors do not parse out the "rsa", "pss", and "sha512" portions
of the identifier to determine parameters of the signing algorithm
from the string.

5.1.1.

6.1.1. Registration Template

Algorithm Name:
An identifier for the HTTP Signature Algorithm. The name MUST be
an ASCII string consisting only of lower-case characters (""a"" -
""z""), digits (""0"" - ""9""), and hyphens (""-""), and SHOULD
NOT exceed 20 characters in length. The identifier MUST be unique
within the context of the registry.

Status:
A brief text description of the status of the algorithm. The
description MUST begin with one of "Active" or "Deprecated", and
MAY provide further context or explanation as to the reason for
the status.

Description:
A brief description of the algorithm used to sign the signature
input string.

Specification document(s):
Reference to the document(s) that specify the token endpoint
authorization method, preferably including a URI that can be used
to retrieve a copy of the document(s). An indication of the
relevant sections may also be included but is not required.

5.1.2.

6.1.2. Initial Contents

5.1.2.1.

6.1.2.1. rsa-pss-sha512

Algorithm Name:
"rsa-pss-sha512"

Status:
Active

Definition:
RSASSA-PSS using SHA-256

Specification document(s):
[[This document]], Section 3.3.1

5.1.2.2.

6.1.2.2. rsa-v1_5-sha256

Algorithm Name:
"rsa-v1_5-sha256"

Status:
Active

Description:
RSASSA-PKCS1-v1_5 using SHA-256

Specification document(s):
[[This document]], Section 3.3.2

5.1.2.3.

6.1.2.3. hmac-sha256

Algorithm Name:
"hmac-sha256"

Status:
Active

Description:
HMAC using SHA-256

Specification document(s):
[[This document]], Section 3.3.3

5.1.2.4.

6.1.2.4. ecdsa-p256-sha256

Algorithm Name:
"ecdsa-p256-sha256"

Status:
Active

Description:
ECDSA using curve P-256 DSS and SHA-256

Specification document(s):
[[This document]], Section 3.3.4

5.2.

6.2. HTTP Signature Metadata Parameters Registry

This document defines the "Signature-Input" Structured Header, whose
member signature parameters structure, the values
of which may have parameters containing metadata about a message
signature. IANA is asked to create and maintain a new registry
titled "HTTP Signature Metadata Parameters" to record and maintain
the set of parameters defined for use with member values in the
"Signature-Input" Structured Header.
signature parameters structure. Initial values for this registry are
given in Section 5.2.2. 6.2.2. Future assignments and modifications to
existing assignments are to be made through the Expert Review
registration policy [RFC8126] and shall follow the template presented
in Section 5.2.1.

5.2.1. 6.2.1.

6.2.1. Registration Template
5.2.2.

6.2.2. Initial Contents

The table below contains the initial contents of the HTTP Signature
Metadata Parameters Registry. Each row in the table represents a
distinct entry in the registry.

Table 4: 3: Initial contents of the HTTP Signature
Metadata Parameters Registry.

5.3.

6.3. HTTP Signature Specialty Content Component Identifiers Registry

This document defines a method for canonicalizing HTTP message
content,
components, including content components that can be generated from the
context of the HTTP message outside of the HTTP headers. This content is fields. These
components are identified by a unique key. string, known as the component
identifier. IANA is asked to create and maintain a new registry
typed "HTTP Signature Specialty Content Component Identifiers" to record and
maintain the set of non-header content non-field component identifiers and the methods
to produce their canonicalization method. associated component values. Initial values for
this registry are given in Section 5.3.2. 6.3.2. Future assignments and
modifications to existing assignments are to be made through the
Expert Review registration policy [RFC8126] and shall follow the
template presented in Section 5.3.1.

5.3.1. 6.3.1.

6.3.1. Registration Template

5.3.2.

6.3.2. Initial Contents

The table below contains the initial contents of the HTTP Signature
Specialty Content Component Identifiers Registry.

+===================+========+================================+

Table 5: 4: Initial contents of the HTTP Signature Specialty
Content Component
Identifiers Registry.

7. Security Considerations

(( TODO: need to dive deeper on this section; not sure how much of
what's referenced below is actually applicable, or if it covers
everything we need to worry about. ))

(( TODO: Should provide some recommendations on how to determine what
content needs
components need to be signed for a given use case. ))
There are a number of security considerations to take into account
when implementing or utilizing this specification. A thorough
security analysis of this protocol, including its strengths and
weaknesses, can be found in [WP-HTTP-Sig-Audit].

8. References

7.1.

8.1. Normative References

[FIPS186-4]
"Digital Signature Standard (DSS)", 2013,
<https://csrc.nist.gov/publications/detail/fips/186/4/
final>.

[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/rfc/rfc7540>.

[HTMLURL] "URL (Living Standard)", 2021,
<https://url.spec.whatwg.org/>.

[MESSAGING]
Fielding, R., Ed. R. T., Nottingham, M., and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/rfc/rfc7230>.
"HTTP/1.1", Work in Progress, Internet-Draft, draft-ietf-
httpbis-messaging-17, 25 July 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
messaging-17>.

[POSIX.1] "The Open Group Base Specifications Issue 7, 2018
edition", 2018,
<https://pubs.opengroup.org/onlinepubs/9699919799/>.

[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/rfc/rfc2104>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/rfc/rfc8792>.

[RFC8941] Nottingham, M. and P-H. Kamp, "Structured Field Values for
HTTP", RFC 8941, DOI 10.17487/RFC8941, February 2021,
<https://www.rfc-editor.org/rfc/rfc8941>.

[SEMANTICS]
Fielding, R., Ed. R. T., Nottingham, M., and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/rfc/rfc7231>.

7.2. "HTTP
Semantics", Work in Progress, Internet-Draft, draft-ietf-
httpbis-semantics-17, 25 July 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
semantics-17>.

8.2. Informative References

[I-D.ietf-httpbis-client-cert-field]
Campbell, B. and M. Bishop, "Client-Cert HTTP Header
Field: Conveying Client Certificate Information from TLS
Terminating Reverse Proxies to Origin Server
Applications", Work in Progress, Internet-Draft, draft-
ietf-httpbis-client-cert-field-00, 8 June 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
client-cert-field-00>.

[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/rfc/rfc6234>.

[RFC7239] Petersson, A. and M. Nilsson, "Forwarded HTTP Extension",
RFC 7239, DOI 10.17487/RFC7239, June 2014,
<https://www.rfc-editor.org/rfc/rfc7239>.

[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/rfc/rfc7517>.

[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/rfc/rfc7518>.

[RFC8017] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
"PKCS #1: RSA Cryptography Specifications Version 2.2",
RFC 8017, DOI 10.17487/RFC8017, November 2016,
<https://www.rfc-editor.org/rfc/rfc8017>.

[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>.

[TLS] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.

[WP-HTTP-Sig-Audit]
"Security Considerations for HTTP Signatures", 2013,
<https://web-payments.org/specs/source/http-signatures-
audit/>.

Appendix A. Detecting HTTP Message Signatures

There have been many attempts to create signed HTTP messages in the
past, including other non-standard definitions of the "Signature"
header
field used within this specification. It is recommended that
developers wishing to support both this specification and other
historical drafts do so carefully and deliberately, as
incompatibilities between this specification and various versions of
other drafts could lead to unexpected problems.

It is recommended that implementers first detect and validate the
"Signature-Input" header field defined in this specification to detect that
this standard is in use and not an alternative. If the "Signature-
Input" header field is present, all "Signature" headers fields can be parsed and
interpreted in the context of this draft.

Appendix B. Examples

B.1. Example Keys

This section provides cryptographic keys that are referenced in
example signatures throughout this document. These keys MUST NOT be
used for any purpose other than testing.

The key identifiers for each key are used throughout the examples in
this specification. It is assumed for these examples that the signer
and verifier can unambiguously dereference all key identifiers used
here, and that the keys and algorithms used are appropriate for the
context in which the signature is presented.

B.1.1. Example Key RSA test

The following key is a 2048-bit RSA public and private key pair,
referred to in this document as "test-key-rsa":

B.1.2. Example RSA PSS Key

The following key is a 2048-bit RSA public and private key pair,
referred to in this document as "test-key-rsa-pss":

B.1.3. Example ECC P-256 Test Key

The following key is an elliptical curve key over the curve P-256,
referred to in this document as "test-key-ecc-p256".

-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEqIVYZVLCrPZHGHjP17CTW0/+D9Lf
w0EkjqF7xB4FivAxzic30tMM4GF+hR6Dxh71Z50VGGdldkkDXZCnTNnoXQ==
-----END PUBLIC KEY-----

B.1.4. Example Shared Secret

The following shared secret is 64 randomly-generated bytes encoded in
Base64, referred to in this document as "test-shared-secret".

NOTE: '\' line wrapping per RFC 8792

uzvJfB4u3N0Jy4T7NZ75MDVcr8zSTInedJtkgcu46YW4XByzNJjxBdtjUkdJPBt\
bmHhIDi6pcl8jsasjlTMtDQ==

B.2. Test Cases

This section provides non-normative examples that may may be used as test
cases to validate implementation correctness. These examples are
based on the following HTTP messages:

For requests, this "test-request" message is used:

POST /foo?param=value&pet=dog HTTP/1.1
Host: example.com
Date: Tue, 20 Apr 2021 02:07:55 GMT
Content-Type: application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18

{"hello": "world"}

For responses, this "test-response" message is used:

HTTP/1.1 200 OK
Date: Tue, 20 Apr 2021 02:07:56 GMT
Content-Type: application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18

{"hello": "world"}

B.2.1. Minimal Signature Using rsa-pss-sha512

This example presents a minimal "Signature-Input" and "Signature"
header for a signature using the "rsa-pss-sha512" algorithm over
"test-request", covering none of the components of the HTTP message
request but providing a timestamped signature proof of possession of
the key.

The corresponding signature input is:

NOTE: '\' line wrapping per RFC 8792

"@signature-params": ();created=1618884475\
;keyid="test-key-rsa-pss";alg="rsa-pss-sha512"

This results in the following "Signature-Input" and "Signature"
headers being added to the message:

NOTE: '\' line wrapping per RFC 8792

Signature-Input: sig1=();created=1618884475\
;keyid="test-key-rsa-pss";alg="rsa-pss-sha512"
Signature: sig1=:HWP69ZNiom9Obu1KIdqPPcu/C1a5ZUMBbqS/xwJECV8bhIQVmE\
AAAzz8LQPvtP1iFSxxluDO1KE9b8L+O64LEOvhwYdDctV5+E39Jy1eJiD7nYREBgx\
TpdUfzTO+Trath0vZdTylFlxK4H3l3s/cuFhnOCxmFYgEa+cw+StBRgY1JtafSFwN\
cZgLxVwialuH5VnqJS4JN8PHD91XLfkjMscTo4jmVMpFd3iLVe0hqVFl7MDt6TMkw\
IyVFnEZ7B/VIQofdShO+C/7MuupCSLVjQz5xA+Zs6Hw+W9ESD/6BuGs6LF1TcKLxW\
+5K+2zvDY/Cia34HNpRW5io7Iv9/b7iQ==:

Note that since the covered components list is empty, this signature
could be used as test
cases applied by an attacker to validate implementation correctness. These examples are
based on the following an unrelated HTTP messages:

For requests, this "test-request" message message.
Therefore, use of an empty covered components set is used:

POST /foo?param=value&pet=dog HTTP/1.1
Host: discouraged.

B.2.2. Selective Covered Components using rsa-pss-sha512

This example covers additional components in "test-request" using the
"rsa-pss-sha512" algorithm.

The corresponding signature input is:

NOTE: '\' line wrapping per RFC 8792

"@authority": example.com
Date: Tue, 20 Apr 2021 02:07:55 GMT
Content-Type:
"content-type": application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18

{"hello": "world"}

For responses, this "test-response"
"@signature-params": ("@authority" "content-type")\
;created=1618884475;keyid="test-key-rsa-pss"

This results in the following "Signature-Input" and "Signature"
headers being added to the message:

NOTE: '\' line wrapping per RFC 8792

Signature-Input: sig1=("@authority" "content-type")\
;created=1618884475;keyid="test-key-rsa-pss"
Signature: sig1=:ik+OtGmM/kFqENDf9Plm8AmPtqtC7C9a+zYSaxr58b/E6h81gh\
JS3PcH+m1asiMp8yvccnO/RfaexnqanVB3C72WRNZN7skPTJmUVmoIeqZncdP2mlf\
xlLP6UbkrgYsk91NS6nwkKC6RRgLhBFqzP42oq8D2336OiQPDAo/04SxZt4Wx9nDG\
uy2SfZJUhsJqZyEWRk4204x7YEB3VxDAAlVgGt8ewilWbIKKTOKp3ymUeQIwptqYw\
v0l8mN404PPzRBTpB7+HpClyK4CNp+SVv46+6sHMfJU4taz10s/NoYRmYCGXyadzY\
YDj0BYnFdERB6NblI/AOWFGl5Axhhmjg==:

B.2.3. Full Coverage using rsa-pss-sha512

This example covers all headers in "test-request" (including the
message is used:

HTTP/1.1 200 OK
Date: body "Digest") plus various elements of the control data,
using the "rsa-pss-sha512" algorithm.

The corresponding signature input is:

NOTE: '\' line wrapping per RFC 8792

"date": Tue, 20 Apr 2021 02:07:56 GMT
Content-Type:
"@method": POST
"@path": /foo
"@query": ?param=value&pet=dog
"@authority": example.com
"content-type": application/json
Digest:
"digest": SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length:
"content-length": 18

{"hello": "world"}

B.2.1. Minimal Signature Header using rsa-pss-sha512
"@signature-params": ("date" "@method" "@path" "@query" \
"@authority" "content-type" "digest" "content-length")\
;created=1618884475;keyid="test-key-rsa-pss"

This example presents a minimal results in the following "Signature-Input" and "Signature"
headers being added to the message:

NOTE: '\' line wrapping per RFC 8792

Signature-Input: sig1=("date" "@method" "@path" "@query" \
"@authority" "content-type" "digest" "content-length")\
;created=1618884475;keyid="test-key-rsa-pss"
Signature: sig1=:JuJnJMFGD4HMysAGsfOY6N5ZTZUknsQUdClNG51VezDgPUOW03\
QMe74vbIdndKwW1BBrHOHR3NzKGYZJ7X3ur23FMCdANe4VmKb3Rc1Q/5YxOO8p7Ko\
yfVa4uUcMk5jB9KAn1M1MbgBnqwZkRWsbv8ocCqrnD85Kavr73lx51k1/gU8w673W\
T/oBtxPtAn1eFjUyIKyA+XD7kYph82I+ahvm0pSgDPagu917SlqUjeaQaNnlZzO03\
Iy1RZ5XpgbNeDLCqSLuZFVID80EohC2CQ1cL5svjslrlCNstd2JCLmhjL7xV3NYXe\
rLim4bqUQGRgDwNJRnqobpS6C1NBns/Q==:

Note in this example that the value of the "Date" header for a and the
value of the "created" signature using parameter need not be the same.
This is due to the fact that the "Date" header is added when creating
the HTTP Message and the "created" parameter is populated when
creating the signature over that message, and these two times could
vary. If the "rsa-pss-sha512" algorithm over
"test-request", covering none of "Date" header is covered by the content signature, it is up to
the verifier to determine whether its value has to match that of the HTTP message
request but providing
"created" parameter or not.

B.2.4. Signing a timestamped signature proof of possession Response using ecdsa-p256-sha256

This example covers portions of the key. "test-response" response message
using the "ecdsa-p256-sha256" algorithm and the key "test-key-ecc-
p256".

The corresponding signature input is:

NOTE: '\' line wrapping per RFC 8792

"content-type": application/json
"digest": SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
"content-length": 18
"@signature-params": ();created=1618884475\
;keyid="test-key-rsa-pss";alg="rsa-pss-sha512" ("content-type" "digest" "content-length")\
;created=1618884475;keyid="test-key-ecc-p256"

This results in the following "Signature-Input" and "Signature"
headers being added to the message:

NOTE: '\' line wrapping per RFC 8792

Signature-Input: sig1=();created=1618884475\
;keyid="test-key-rsa-pss";alg="rsa-pss-sha512" sig1=("content-type" "digest" "content-length")\
;created=1618884475;keyid="test-key-ecc-p256"
Signature: sig1=:VrfdC2KEFFLoGMYTbQz4PSlKat4hAxcr5XkVN7Mm/7OQQJG+uX\
gOez7kA6n/yTCaR1VL+FmJd2IVFCsUfcc/jO9siZK3siadoK1Dfgp2ieh9eO781ty\
SS70OwvAkdORuQLWDnaDMRDlQhg5sNP6JaQghFLqD4qgFrM9HMPxLrznhAQugJ0Fd\
RZLtSpnjECW6qsu2PVRoCYfnwe4gu8TfqH5GDx2SkpCF9BQ8CijuIWlOg7QP73tKt\
QNp65u14Si9VEVXHWGiLw4blyPLzWz/fqJbdLaq94Ep60Nq8WjYEAInYH6KyV7EAD\
60LXdspwF50R3dkWXJP/x+gkAHSMsxbg==:

B.2.2. Header Coverage sig1=:n8RKXkj0iseWDmC6PNSQ1GX2R9650v+lhbb6rTGoSrSSx18zmn\
6fPOtBx48/WffYLO0n1RHHf9scvNGAgGq52Q==:

B.2.5. Signing a Request using rsa-pss-sha512 hmac-sha256

This example covers all portions of the specified headers in "test-request"
except for the body digest header using the "rsa-pss-sha512"
algorithm. "hmac-
sha256" algorithm and the secret "test-shared-secret".

The corresponding signature input is:

"host":

NOTE: '\' line wrapping per RFC 8792

"@authority": example.com
"date": Tue, 20 Apr 2021 02:07:55 GMT
"content-type": application/json
"@signature-params": ("host" ("@authority" "date" "content-type")\
;created=1618884475;keyid="test-key-rsa-pss"
;created=1618884475;keyid="test-shared-secret"

This results in the following "Signature-Input" and "Signature"
headers being added to the message:

NOTE: '\' line wrapping per RFC 8792

Signature-Input: sig1=("host" sig1=("@authority" "date" "content-type")\
;created=1618884475;keyid="test-key-rsa-pss"
;created=1618884475;keyid="test-shared-secret"
Signature: sig1=:Zu48JBrHlXN+hVj3T5fPQUjMNEEhABM5vNmiWuUUl7BWNid5Rz\
OH1tEjVi+jObYkYT8p09lZ2hrNuU3xm+JUBT8WNIlopJtt0EzxFnjGlHvkhu3KbJf\
xNlvCJVlOEdR4AivDLMeK/ZgASpZ7py1UNHJqRyGCYkYpeedinXUertL/ySNp+VbK\
2O/qCoui2jFgff2kXQd6rjL1Up83Fpr+/KoZ6HQkv3qwBdMBDyHQykfZHhLn4AO1I\
G+vKhOLJQDfaLsJ/fYfzsgc1s46j3GpPPD/W2nEEtdhNwu7oXq81qVRsENChIu1XI\
FKR9q7WpyHDKEWTtaNZDS8TFvIQRU22w==:

B.2.3. Full Coverage using rsa-pss-sha512

This example covers all headers sig1=:fN3AMNGbx0V/cIEKkZOvLOoC3InI+lM2+gTv22x3ia8=:

B.3. TLS-Terminating Proxies

In this example, there is a TLS-terminating reverse proxy sitting in "test-request" plus
front of the resource. The client does not sign the request
target but
instead uses mutual TLS to make its call. The terminating proxy
validates the TLS stream and message body digest using injects a "Client-Cert" header according
to [I-D.ietf-httpbis-client-cert-field]. By signing this header
field, a reverse proxy can not only attest to its own validation of
the "rsa-pss-sha512" algorithm. initial request but also authenticate itself to the backend
system independently of the client's actions. The corresponding signature input is:

"@request-target": post /foo?param=value&pet=dog
"host": client makes the
following request to the TLS terminating proxy using mutual TLS:

POST /foo?Param=value&pet=Dog HTTP/1.1
Host: example.com
"date":
Date: Tue, 20 Apr 2021 02:07:55 GMT
Content-Type: application/json
Content-Length: 18

{"hello": "world"}

The proxy processes the TLS connection and extracts the client's TLS
certificate to a "Client-Cert" header field and passes it along to
the internal service hosted at "service.internal.example". This
results in the following unsigned request:

NOTE: '\' line wrapping per RFC 8792

POST /foo?Param=value&pet=Dog HTTP/1.1
Host: service.internal.example
Date: Tue, 20 Apr 2021 02:07:55 GMT
"content-type":
Content-Type: application/json
"digest": SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
"content-length":
Content-Length: 18
"@signature-params": ("@request-target" "host" "date" \
"content-type" "digest" "content-length");created=1618884475\
;keyid="test-key-rsa-pss"

This results in
Client-Cert: :MIIBqDCCAU6gAwIBAgIBBzAKBggqhkjOPQQDAjA6MRswGQYDVQQKD\
BJMZXQncyBBdXRoZW50aWNhdGUxGzAZBgNVBAMMEkxBIEludGVybWVkaWF0ZSBDQT\
AeFw0yMDAxMTQyMjU1MzNaFw0yMTAxMjMyMjU1MzNaMA0xCzAJBgNVBAMMAkJDMFk\
wEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE8YnXXfaUgmnMtOXU/IncWalRhebrXmck\
C8vdgJ1p5Be5F/3YC8OthxM4+k1M6aEAEFcGzkJiNy6J84y7uzo9M6NyMHAwCQYDV\
R0TBAIwADAfBgNVHSMEGDAWgBRm3WjLa38lbEYCuiCPct0ZaSED2DAOBgNVHQ8BAf\
8EBAMCBsAwEwYDVR0lBAwwCgYIKwYBBQUHAwIwHQYDVR0RAQH/BBMwEYEPYmRjQGV\
4YW1wbGUuY29tMAoGCCqGSM49BAMCA0gAMEUCIBHda/r1vaL6G3VliL4/Di6YK0Q6\
bMjeSkC3dFCOOB8TAiEAx/kHSB4urmiZ0NX5r5XarmPk0wmuydBVoU4hBVZ1yhk=:

{"hello": "world"}

Without a signature, the following "Signature-Input" and "Signature"
headers being added internal service would need to trust that
the message:

Signature-Input: sig1=("@request-target" "host" "date" \
"content-type" "digest" "content-length");created=1618884475\
;keyid="test-key-rsa-pss"
Signature: \
sig1=:iD5NhkJoGSuuTpWMzS0BI47DfbWwsGmHHLTwOxT0n+0cQFSC+1c26B7IOfI\
RTYofqD0sfYYrnSwCvWJfA1zthAEv9J1CxS/CZXe7CQvFpuKuFJxMpkAzVYdE/TA6\
fELxNZy9RJEWZUPBU4+aJ26d8PC0XhPObXe6JkP6/C7XvG2QinsDde7rduMdhFN/H\
j2MuX1Ipzvv4EgbHJdKwmWRNamfmKJZC4U5Tn0F58lzGF+WIpU73V67/6aSGvJGM5\
7U9bRHrBB7ExuQhOX2J2dvJMYkE33pEJA70XBUp9ZvciTI+vjIUgUQ2oRww3huWML\
mMMqEc95CliwIoL5aBdCnlQ==:

B.2.4. Signing a Response using ecdsa-p256-sha256

This example covers incoming connection has the right information. By signing the
"Client-Cert" header and other portions of the "test-response" response message
using internal request, the "ecdsa-p256-sha256" algorithm
internal service can be assured that the correct party, the trusted
proxy, has processed the request and presented it to the key "test-key-ecc-
p256". correct
service. The corresponding proxy's signature input is:

"date": Tue, 20 Apr 2021 02:07:56 GMT
"content-type": application/json
"digest": SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
"content-length": 18 consists of the following:

NOTE: '\' line wrapping per RFC 8792

"@path": /foo
"@query": Param=value&pet=Dog
"@method": POST
"@authority": service.internal.example
"client-cert": :MIIBqDCCAU6gAwIBAgIBBzAKBggqhkjOPQQDAjA6MRswGQYDVQQ\
KDBJMZXQncyBBdXRoZW50aWNhdGUxGzAZBgNVBAMMEkxBIEludGVybWVkaWF0ZSBD\
QTAeFw0yMDAxMTQyMjU1MzNaFw0yMTAxMjMyMjU1MzNaMA0xCzAJBgNVBAMMAkJDM\
FkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE8YnXXfaUgmnMtOXU/IncWalRhebrXm\
ckC8vdgJ1p5Be5F/3YC8OthxM4+k1M6aEAEFcGzkJiNy6J84y7uzo9M6NyMHAwCQY\
DVR0TBAIwADAfBgNVHSMEGDAWgBRm3WjLa38lbEYCuiCPct0ZaSED2DAOBgNVHQ8B\
Af8EBAMCBsAwEwYDVR0lBAwwCgYIKwYBBQUHAwIwHQYDVR0RAQH/BBMwEYEPYmRjQ\
GV4YW1wbGUuY29tMAoGCCqGSM49BAMCA0gAMEUCIBHda/r1vaL6G3VliL4/Di6YK0\
Q6bMjeSkC3dFCOOB8TAiEAx/kHSB4urmiZ0NX5r5XarmPk0wmuydBVoU4hBVZ1yhk=:
"@signature-params": ("date" "content-type" "digest" ("@path" "@query" "@method" "@authority" \
"content-length");created=1618884475;keyid="test-key-ecc-p256"
"client-cert");created=1618884475;keyid="test-key-ecc-p256"

This results in the following "Signature-Input" and "Signature"
headers being added to the message:

Signature-Input: sig1=("date" "content-type" "digest" \
"content-length");created=1618884475;keyid="test-key-ecc-p256"
Signature: \
sig1=:3zmRDW6r50/RETqqhtx/N5sdd5eTh8xmHdsrYRK9wK4rCNEwLjCOBlcQxTL\
2oJTCWGRkuqE2r9KyqZFY9jd+NQ==:

B.2.5. Signing a Request using hmac-sha256

This example covers portions of signature:

NOTE: '\' line wrapping per RFC 8792

5gudRjXaHrAYbEaQUOoY9TuvqWOdPcspkp7YyKCB0XhyAG9cB715hucPPanEK0OVyiN\
LJqcoq2Yn1DPWQcnbog==

Which results in the "test-request" using following signed request sent from the "hmac-
sha256" algorithm and proxy to
the secret "test-shared-secret".

The corresponding signature input is:

"host": example.com
"date": internal service:

NOTE: '\' line wrapping per RFC 8792

POST /foo?Param=value&pet=Dog HTTP/1.1
Host: service.internal.example
Date: Tue, 20 Apr 2021 02:07:55 GMT
"content-type":
Content-Type: application/json
"@signature-params": ("host" "date" "content-type")\
;created=1618884475;keyid="test-shared-secret"

This results in
Content-Length: 18
Client-Cert: :MIIBqDCCAU6gAwIBAgIBBzAKBggqhkjOPQQDAjA6MRswGQYDVQQKD\
BJMZXQncyBBdXRoZW50aWNhdGUxGzAZBgNVBAMMEkxBIEludGVybWVkaWF0ZSBDQT\
AeFw0yMDAxMTQyMjU1MzNaFw0yMTAxMjMyMjU1MzNaMA0xCzAJBgNVBAMMAkJDMFk\
wEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE8YnXXfaUgmnMtOXU/IncWalRhebrXmck\
C8vdgJ1p5Be5F/3YC8OthxM4+k1M6aEAEFcGzkJiNy6J84y7uzo9M6NyMHAwCQYDV\
R0TBAIwADAfBgNVHSMEGDAWgBRm3WjLa38lbEYCuiCPct0ZaSED2DAOBgNVHQ8BAf\
8EBAMCBsAwEwYDVR0lBAwwCgYIKwYBBQUHAwIwHQYDVR0RAQH/BBMwEYEPYmRjQGV\
4YW1wbGUuY29tMAoGCCqGSM49BAMCA0gAMEUCIBHda/r1vaL6G3VliL4/Di6YK0Q6\
bMjeSkC3dFCOOB8TAiEAx/kHSB4urmiZ0NX5r5XarmPk0wmuydBVoU4hBVZ1yhk=:
Signature-Input: ttrp=("@path" "@query" "@method" "@authority" \
"client-cert");created=1618884475;keyid="test-key-ecc-p256"
Signature: ttrp=:5gudRjXaHrAYbEaQUOoY9TuvqWOdPcspkp7YyKCB0XhyAG9cB7\
15hucPPanEK0OVyiNLJqcoq2Yn1DPWQcnbog==:

{"hello": "world"}

The internal service can validate the following "Signature-Input" proxy's signature and "Signature"
headers being added therefore
be able to trust that the message:

Signature-Input: sig1=("host" "date" "content-type")\
;created=1618884475;keyid="test-shared-secret"
Signature: sig1=:x54VEvVOb0TMw8fUbsWdUHqqqOre+K7sB/LqHQvnfaQ=: client's certificate has been appropriately
processed.

Acknowledgements

This specification was initially based on the draft-cavage-http-
signatures internet draft. The editors would like to thank the
authors of that draft, Mark Cavage and Manu Sporny, for their work on
that draft and their continuing contributions.

The editors would also like to thank the following individuals for
feedback, insight, and implementation of this draft and its
predecessors (in alphabetical order): Mark Adamcin, Mark Allen, Paul
Annesley, Karl Boehlmark, Stephane Bortzmeyer, Sarven Capadisli, Liam
Dennehy, ductm54, Stephen Farrell, Phillip Hallam-Baker, Eric Holmes,
Andrey Kislyuk, Adam Knight, Dave Lehn, Dave Longley, Ilari
Liusvaara, James H. Manger, Kathleen Moriarty, Mark Nottingham, Yoav
Nir, Adrian Palmer, Lucas Pardue, Roberto Polli, Julian Reschke,
Michael Richardson, Wojciech Rygielski, Adam Scarr, Cory J. Slep,
Dirk Stein, Henry Story, Lukasz Szewc, Chris Webber, and Jeffrey
Yasskin.

Document History

_RFC EDITOR: please remove this section before publication_

* draft-ietf-httpbis-message-signatures

- -06

o Updated language for message components, including
identifiers and values.

o Clarified that Signature-Input and Signature are fields
which can be used as headers or trailers.

o Add "Accept-Signature" field and semantics for signature
negotiation.

o Define new specialty content identifiers, re-defined
request-target identifier.

o Added request-response binding.

- -05

o Remove list prefixes.

o Clarify signature algorithm parameters.

o Update and fix examples.

o Add examples for ECC and HMAC.

- -04

o Moved signature component definitions up to intro.

o Created formal function definitions for algorithms to
fulfill.

o Updated all examples.

o Added nonce parameter field.

- -03

o Clarified signing and verification processes.

o Updated algorithm and key selection method.

o Clearly defined core algorithm set.

o Defined JOSE signature mapping process.

o Removed legacy signature methods.

o Define signature parameters separately from "signature"
object model.

o Define serialization values for signature-input header based
on signature input.

- -02

o Removed editorial comments on document sources.

o Removed in-document issues list in favor of tracked issues.

o Replaced unstructured "Signature" header with "Signature-
Input" and "Signature" Dictionary Structured Header Fields.

o Defined content identifiers for individual Dictionary
members, e.g., ""x-dictionary-field";key=member-name".

o Defined content identifiers for first N members of a List,
e.g., ""x-list-field":prefix=4".

o Fixed up examples.

o Updated introduction now that it's adopted.

o Defined specialty content identifiers and a means to extend
them.

o Required signature parameters to be included in signature.

o Added guidance on backwards compatibility, detection, and
use of signature methods.

- -01
o Strengthened requirement for content identifiers for header
fields to be lower-case (changed from SHOULD to MUST).

o Added real example values for Creation Time and Expiration
Time.

o Minor editorial corrections and readability improvements.

- -00

o Initialized from draft-richanna-http-message-signatures-00,
following adoption by the working group.

* draft-richanna-http-message-signatures

- -00

o Converted to xml2rfc v3 and reformatted to comply with RFC
style guides.

o Removed Signature auth-scheme definition and related
content.

o Removed conflicting normative requirements for use of
algorithm parameter. Now MUST NOT be relied upon.

o Removed Extensions appendix.

o Rewrote abstract and introduction to explain context and
need, and challenges inherent in signing HTTP messages.

o Rewrote and heavily expanded algorithm definition, retaining
normative requirements.

o Added definitions for key terms, referenced RFC 7230 for
HTTP terms.

o Added examples for canonicalization and signature generation
steps.

o Rewrote Signature header definition, retaining normative
requirements.

o Added default values for algorithm and expires parameters.

o Rewrote HTTP Signature Algorithms registry definition.
Added change control policy and registry template. Removed
suggested URI.

o Added IANA HTTP Signature Parameter registry.

o Added additional normative and informative references.

o Added Topics for Working Group Discussion section, to be
removed prior to publication as an RFC.

Authors' Addresses

Annabelle Backman (editor)
Amazon
P.O. Box 81226
Seattle, WA 98108-1226
United States of America

Email: richanna@amazon.com
URI: https://www.amazon.com/

Justin Richer
Bespoke Engineering

Email: ietf@justin.richer.org
URI: https://bspk.io/

Manu Sporny
Digital Bazaar
203 Roanoke Street W.
Blacksburg, VA 24060
United States of America

Email: msporny@digitalbazaar.com
URI: https://manu.sporny.org/