--- 1/draft-ietf-httpbis-message-signatures-01.txt 2021-03-22 13:36:55.448988860 -0700 +++ 2/draft-ietf-httpbis-message-signatures-02.txt 2021-03-22 13:36:55.520990651 -0700 @@ -1,165 +1,134 @@ HTTP A. Backman, Ed. Internet-Draft Amazon Intended status: Standards Track J. Richer -Expires: 21 May 2021 Bespoke Engineering +Expires: 16 September 2021 Bespoke Engineering M. Sporny Digital Bazaar - 17 November 2020 + 15 March 2021 Signing HTTP Messages - draft-ietf-httpbis-message-signatures-01 + draft-ietf-httpbis-message-signatures-02 Abstract This document describes a mechanism for creating, encoding, and verifying digital signatures or message authentication codes over content within 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. Note to Readers _RFC EDITOR: please remove this section before publication_ - This work was originally based on draft-cavage-http-signatures-12, - but has since diverged from it, to reflect discussion since adoption - by the HTTP Working Group. In particular, it addresses issues that - have been identified, and adds features to support new use cases. It - is a work-in-progress and not yet suitable for deployment. + 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 This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on 21 May 2021. + This Internet-Draft will expire on 16 September 2021. Copyright Notice - Copyright (c) 2020 IETF Trust and the persons identified as the + Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 - 1.1. Requirements Discussion . . . . . . . . . . . . . . . . . 5 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 + 1.1. Requirements Discussion . . . . . . . . . . . . . . . . . 4 1.2. HTTP Message Transformations . . . . . . . . . . . . . . 5 - 1.3. Safe Transformations . . . . . . . . . . . . . . . . . . 6 - 1.4. Conventions and Terminology . . . . . . . . . . . . . . . 7 + 1.3. Safe Transformations . . . . . . . . . . . . . . . . . . 5 + 1.4. Conventions and Terminology . . . . . . . . . . . . . . . 6 + 1.5. Application of HTTP Message Signatures . . . . . . . . . 7 2. Identifying and Canonicalizing Content . . . . . . . . . . . 8 - 2.1. HTTP Header Fields . . . . . . . . . . . . . . . . . . . 8 - 2.1.1. Canonicalization Examples . . . . . . . . . . . . . . 9 - 2.2. Dictionary Structured Field Members . . . . . . . . . . . 9 + 2.1. HTTP Headers . . . . . . . . . . . . . . . . . . . . . . 8 + 2.1.1. Canonicalized Structured HTTP Headers . . . . . . . . 9 + 2.1.2. Canonicalization Examples . . . . . . . . . . . . . . 9 + 2.2. Dictionary Structured Field Members . . . . . . . . . . . 10 2.2.1. Canonicalization Examples . . . . . . . . . . . . . . 10 - 2.3. List Prefixes . . . . . . . . . . . . . . . . . . . . . . 10 - 2.3.1. Canonicalization Examples . . . . . . . . . . . . . . 10 - 2.4. Signature Creation Time . . . . . . . . . . . . . . . . . 11 - 2.5. Signature Expiration Time . . . . . . . . . . . . . . . . 11 - 2.6. Target Endpoint . . . . . . . . . . . . . . . . . . . . . 11 - 2.6.1. Canonicalization Examples . . . . . . . . . . . . . . 12 - 3. HTTP Message Signatures . . . . . . . . . . . . . . . . . . . 12 - 3.1. Signature Metadata . . . . . . . . . . . . . . . . . . . 13 - 3.2. Creating a Signature . . . . . . . . . . . . . . . . . . 13 - 3.2.1. Choose and Set Signature Metadata Properties . . . . 14 - 3.2.2. Create the Signature Input . . . . . . . . . . . . . 16 - 3.2.3. Sign the Signature Input . . . . . . . . . . . . . . 17 - 3.3. Verifying a Signature . . . . . . . . . . . . . . . . . . 17 - 3.3.1. Enforcing Application Requirements . . . . . . . . . 18 - 4. Including a Message Signature in a Message . . . . . . . . . 19 - 4.1. The 'Signature-Input' HTTP Header . . . . . . . . . . . . 19 - 4.1.1. Metadata Parameters . . . . . . . . . . . . . . . . . 19 - 4.2. The 'Signature' HTTP Header . . . . . . . . . . . . . . . 20 - 4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 20 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 - 5.1. HTTP Signature Algorithms Registry . . . . . . . . . . . 21 - 5.1.1. Registration Template . . . . . . . . . . . . . . . . 21 - 5.1.2. Initial Contents . . . . . . . . . . . . . . . . . . 22 - 5.2. HTTP Signature Metadata Parameters Registry . . . . . . . 24 - 5.2.1. Registration Template . . . . . . . . . . . . . . . . 24 - 5.2.2. Initial Contents . . . . . . . . . . . . . . . . . . 24 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 25 - 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 - 7.1. Normative References . . . . . . . . . . . . . . . . . . 25 - 7.2. Informative References . . . . . . . . . . . . . . . . . 26 - Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 27 - A.1. Example Keys . . . . . . . . . . . . . . . . . . . . . . 27 - A.1.1. Example Key RSA test . . . . . . . . . . . . . . . . 27 - A.2. Example keyId Values . . . . . . . . . . . . . . . . . . 28 - A.3. Test Cases . . . . . . . . . . . . . . . . . . . . . . . 29 - A.3.1. Signature Generation . . . . . . . . . . . . . . . . 29 - A.3.2. Signature Verification . . . . . . . . . . . . . . . 32 - Appendix B. Topics for Working Group Discussion . . . . . . . . 34 - B.1. Issues . . . . . . . . . . . . . . . . . . . . . . . . . 34 - B.1.1. Confusing guidance on algorithm and key - identification . . . . . . . . . . . . . . . . . . . 35 - B.1.2. Lack of definition of keyId hurts interoperability . 35 - B.1.3. Algorithm Registry duplicates work of JWA . . . . . . 35 - B.1.4. Algorithm Registry should not be initialized with - deprecated entries . . . . . . . . . . . . . . . . . 36 - B.1.5. No percent-encoding normalization of path/query . . . 36 - B.1.6. Misleading name for headers parameter . . . . . . . . 36 - B.1.7. Changes to whitespace in header field values break - verification . . . . . . . . . . . . . . . . . . . . 36 - B.1.8. Multiple Set-Cookie headers are not well supported . 36 - B.1.9. Covered Content list is not signed . . . . . . . . . 37 - B.1.10. Algorithm is not signed . . . . . . . . . . . . . . . 37 - B.1.11. Verification key identifier is not signed . . . . . . 37 - B.1.12. Max values, precision for Integer String and Decimal - String not defined . . . . . . . . . . . . . . . . . 37 - B.1.13. keyId parameter value could break list syntax . . . . 37 - B.1.14. Creation Time and Expiration Time do not allow for - clock skew . . . . . . . . . . . . . . . . . . . . . 37 - B.1.15. Should require lowercased header field names as - identifiers . . . . . . . . . . . . . . . . . . . . . 37 - B.1.16. Reconcile Date header and Creation Time . . . . . . . 38 - B.1.17. Remove algorithm-specific rules for content - identifiers . . . . . . . . . . . . . . . . . . . . . 38 - B.1.18. Add guidance for signing compressed headers . . . . . 38 - B.1.19. Transformations to Via header field value break - verification . . . . . . . . . . . . . . . . . . . . 38 - B.1.20. Case changes to case-insensitive header field values - break verification . . . . . . . . . . . . . . . . . 38 - B.1.21. Need more examples for Signature header . . . . . . . 38 - B.1.22. Expiration not needed . . . . . . . . . . . . . . . . 39 + 2.3. List Prefixes . . . . . . . . . . . . . . . . . . . . . . 11 + 2.3.1. Canonicalization Examples . . . . . . . . . . . . . . 11 + 2.4. Specialty Content Fields . . . . . . . . . . . . . . . . 12 + 2.4.1. Request Target . . . . . . . . . . . . . . . . . . . 12 + 2.4.2. Signature Parameters . . . . . . . . . . . . . . . . 13 + 3. HTTP Message Signatures . . . . . . . . . . . . . . . . . . . 14 + 3.1. Signature Metadata . . . . . . . . . . . . . . . . . . . 14 + 3.2. Creating a Signature . . . . . . . . . . . . . . . . . . 16 + 3.2.1. Choose and Set Signature Metadata Properties . . . . 16 + 3.2.2. Create the Signature Input . . . . . . . . . . . . . 18 + 3.2.3. Sign the Signature Input . . . . . . . . . . . . . . 19 + 3.3. Verifying a Signature . . . . . . . . . . . . . . . . . . 19 + 3.3.1. Enforcing Application Requirements . . . . . . . . . 20 - B.2. Features . . . . . . . . . . . . . . . . . . . . . . . . 39 - B.2.1. Define more content identifiers . . . . . . . . . . . 39 - B.2.2. Multiple signature support . . . . . . . . . . . . . 39 - B.2.3. Support for incremental signing of header field value - list items . . . . . . . . . . . . . . . . . . . . . 40 - B.2.4. Support expected authority changes . . . . . . . . . 40 - B.2.5. Support for signing specific cookies . . . . . . . . 40 - Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 41 - Document History . . . . . . . . . . . . . . . . . . . . . . . . 41 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43 + 4. Including a Message Signature in a Message . . . . . . . . . 21 + 4.1. The 'Signature-Input' HTTP Header . . . . . . . . . . . . 21 + 4.2. The 'Signature' HTTP Header . . . . . . . . . . . . . . . 21 + 4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 22 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 + 5.1. HTTP Signature Algorithms Registry . . . . . . . . . . . 23 + 5.1.1. Registration Template . . . . . . . . . . . . . . . . 23 + 5.1.2. Initial Contents . . . . . . . . . . . . . . . . . . 24 + 5.2. HTTP Signature Metadata Parameters Registry . . . . . . . 25 + 5.2.1. Registration Template . . . . . . . . . . . . . . . . 25 + 5.2.2. Initial Contents . . . . . . . . . . . . . . . . . . 25 + 5.3. HTTP Signature Specialty Content Identifiers Registry . . 26 + 5.3.1. Registration Template . . . . . . . . . . . . . . . . 26 + 5.3.2. Initial Contents . . . . . . . . . . . . . . . . . . 26 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 27 + 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 + 7.1. Normative References . . . . . . . . . . . . . . . . . . 27 + 7.2. Informative References . . . . . . . . . . . . . . . . . 28 + Appendix A. Detecting HTTP Message Signatures . . . . . . . . . 29 + Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 29 + B.1. Example Keys . . . . . . . . . . . . . . . . . . . . . . 29 + B.1.1. Example Key RSA test . . . . . . . . . . . . . . . . 29 + B.2. Example keyid Values . . . . . . . . . . . . . . . . . . 30 + B.3. Test Cases . . . . . . . . . . . . . . . . . . . . . . . 31 + B.3.1. Signature Generation . . . . . . . . . . . . . . . . 31 + B.3.2. Signature Verification . . . . . . . . . . . . . . . 34 + Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 36 + Document History . . . . . . . . . . . . . . . . . . . . . . . . 37 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39 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 @@ -303,317 +272,432 @@ 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: - Decimal String - - An Integer String optionally concatenated with a period "." - followed by a second Integer String, representing a positive real - number expressed in base 10. The first Integer String represents - the integral portion of the number, while the optional second - Integer String represents the fractional portion of the number. - (( Editor's note: There's got to be a definition for this that we - can reference. )) - - Integer String - - A US-ASCII string of one or more digits "0-9", representing a - positive integer in base 10. (( Editor's note: There's got to be a - definition for this that we can reference. )) - - Signer - + Signer: The entity that is generating or has generated an HTTP Message Signature. - Verifier + 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. + 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. To improve readability, header fields may be split into multiple lines, using the "obs-fold" syntax. This syntax is deprecated in [MESSAGING], and senders MUST NOT generate messages that include it. + Additionally, some examples use '\' line wrapping for long values + that contain no whitespace, as per [RFC8792]. + +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 content identifiers (Section 2) that are expected and + required. For example, an authorization protocol would mandate + that the "Authorization" header be covered to protect the + authorization credentials, as well as a "*created" field to allow + replay detection. + + * A means of retrieving the key material used to verify the + signature. An application will usually use the "keyid" field of + the "Signature-Input" header value and define rules for resolving + a key from there. + + * A means of determining the signature algorithm used to verify the + signature content is appropriate for the key material. + + * 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. + + The details of this kind of profiling are the purview of the + application and outside the scope of this specification. + 2. Identifying and Canonicalizing Content In order to allow signers and verifiers to establish which content is covered by a signature, this document defines content identifiers for - signature metadata and discrete pieces of message content that may be - covered by an HTTP Message Signature. + data items covered by an HTTP Message Signature. - Some content within HTTP messages may undergo transformations that + Some content within HTTP messages can undergo transformations that change the bitwise value without altering meaning of the content (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 innocuous + to ensure that a signature can be verified despite such intermediary transformations. This document defines rules for each content identifier that transform the identifier's associated content into such a canonical form. - The following sections define content identifiers, their associated - content, and their canonicalization rules. + Content identifiers are defined using production grammar defined by + [RFC8941] section 4. The content identifier is an "sf-string" value. + The content identifier type MAY define parameters which are included + using the "parameters" rule. -2.1. HTTP Header Fields + content-identifier = sf-string parameters - An HTTP header field is identified by 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. + Note that this means the value of the identifier itself is encased in + double quotes, with parameters following as a semicolon-separated + list, such as ""cache-control"", ""date"", or ""@signature-params"". - An HTTP header field value is canonicalized as follows: + The following sections define content identifier types, their + parameters, their associated content, and their canonicalization + rules. + +2.1. HTTP Headers + + The content identifier for an HTTP header is the lowercased form 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 by additional parameters and rules, the HTTP header + field value MUST be canonicalized with the following steps: 1. Create an ordered list of the field values of each instance of the header 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 - value. + " between each item. -2.1.1. Canonicalization Examples + The resulting string is the canonicalized value. + +2.1.1. Canonicalized Structured HTTP Headers + + If value of the the HTTP header in question is a structured field + [RFC8941], the content identifier MAY include the "sf" parameter. If + this parameter is included, the HTTP header value MUST be + canonicalized using the rules specified in [RFC8941] section 4. Note + that this process will replace any optional whitespace with a single + space. + + The resulting string is used as the field 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: HTTP/1.1 200 OK Server: www.example.com Date: Tue, 07 Jun 2014 20:51:35 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 following table shows example canonicalized values for header fields, given that message: - +===================+==================================+ + +=====================+==================================+ | Header Field | Canonicalized Value | - +===================+==================================+ - | cache-control | max-age=60, must-revalidate | - +-------------------+----------------------------------+ - | date | Tue, 07 Jun 2014 20:51:35 GMT | - +-------------------+----------------------------------+ - | server | www.example.com | - +-------------------+----------------------------------+ - | x-empty-header | | - +-------------------+----------------------------------+ - | x-obs-fold-header | Obsolete line folding. | - +-------------------+----------------------------------+ - | x-ows-header | Leading and trailing whitespace. | - +-------------------+----------------------------------+ + +=====================+==================================+ + | "cache-control" | max-age=60, must-revalidate | + +---------------------+----------------------------------+ + | "date" | Tue, 07 Jun 2014 20:51:35 GMT | + +---------------------+----------------------------------+ + | "server" | www.example.com | + +---------------------+----------------------------------+ + | "x-empty-header" | | + +---------------------+----------------------------------+ + | "x-obs-fold-header" | Obsolete line folding. | + +---------------------+----------------------------------+ + | "x-ows-header" | Leading and trailing whitespace. | + +---------------------+----------------------------------+ Table 1: Non-normative examples of header field canonicalization. 2.2. Dictionary Structured Field Members An individual member in the value of a Dictionary Structured Field is - identified by the lowercased field name, followed by a semicolon - "":"", followed by the member name. An individual member in the - value of a Dictionary Structured Field is canonicalized by applying - the serialization algorithm described in Section 4.1.2 of - [StructuredFields] on a Dictionary containing only that member. + identified by using the parameter "key" on the content identifier for + the header. The value of this parameter is a the key being + identified, without any parameters present on that key in the + original dictionary. + + An individual member in the value of a Dictionary Structured Field is + canonicalized by applying the serialization algorithm described in + Section 4.1.2 of [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 the following example header field, whose value is assumed to be a Dictionary: - X-Dictionary: a=1, b=2;x=1;y=2, c=(a, b, c) + X-Dictionary: a=1, b=2;x=1;y=2, c=(a b c) The following table shows example canonicalized values for different content identifiers, given that field: - +====================+=====================+ + +======================+=====================+ | Content Identifier | Canonicalized Value | - +====================+=====================+ - | x-dictionary:a | 1 | - +--------------------+---------------------+ - | x-dictionary:b | 2;x=1;y=2 | - +--------------------+---------------------+ - | x-dictionary:c | (a, b, c) | - +--------------------+---------------------+ + +======================+=====================+ + | "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. List Prefixes A prefix of a List Structured Field consisting of the first N members in the field's value (where N is an integer greater than 0 and less than or equal to the number of members in the List) is identified by - the lowercased field name, followed by a semicolon "":"", followed by - N expressed as an Integer String. A list prefix is canonicalized by - applying the serialization algorithm described in Section 4.1.1 of - [StructuredFields] on a List containing only the first N members as - specified in the list prefix, in the order they appear in the - original List. + the parameter "prefix" with the value of N as an integer. + + A list prefix value is canonicalized by applying the serialization + algorithm described in Section 4.1.1 of [RFC8941] on a List + containing only the first N members as specified in the list prefix, + in the order they appear in the original List. 2.3.1. Canonicalization Examples This section contains non-normative examples of canonicalized values for list prefixes given the following example header fields, whose values are assumed to be Dictionaries: - X-List-A: (a, b, c, d, e, f) + X-List-A: (a b c d e f) X-List-B: () The following table shows example canonicalized values for different content identifiers, given those fields: - +====================+=====================+ + +=====================+=====================+ | Content Identifier | Canonicalized Value | - +====================+=====================+ - | x-list-a:0 | () | - +--------------------+---------------------+ - | x-list-a:1 | (a) | - +--------------------+---------------------+ - | x-list-a:3 | (a, b, c) | - +--------------------+---------------------+ - | x-list-a:6 | (a, b, c, d, e, f) | - +--------------------+---------------------+ - | x-list-b:0 | () | - +--------------------+---------------------+ + +=====================+=====================+ + | "x-list-a";prefix=0 | () | + +---------------------+---------------------+ + | "x-list-a";prefix=1 | (a) | + +---------------------+---------------------+ + | "x-list-a";prefix=3 | (a, b, c) | + +---------------------+---------------------+ + | "x-list-a";prefix=6 | (a, b, c, d, e, f) | + +---------------------+---------------------+ + | "x-list-b";prefix=0 | () | + +---------------------+---------------------+ Table 3: Non-normative examples of list prefix canonicalization. -2.4. Signature Creation Time - - The signature's Creation Time (Section 3.1) is identified by the - "*created" identifier. +2.4. Specialty Content Fields - Its canonicalized value is an Integer String containing the - signature's Creation Time expressed as the number of seconds since - the Epoch, as defined in Section 4.16 - (https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/ - V1_chap04.html#tag_04_16) of [POSIX.1]. + Content not found in an HTTP header can be included in the signature + base string by defining a content identifier and the canonicalization + method for its content. - The use of seconds since the Epoch to canonicalize a timestamp - simplifies processing and avoids timezone management required by - specifications such as [RFC3339]. + To differentiate speciality content identifiers from HTTP headers, + specialty content identifiers MUST start with the "at" "@" character. + This specification defines the following specialty content + identifiers: -2.5. Signature Expiration Time + @request-target The target request endpoint. Section 2.4.1 - The signature's Expiration Time (Section 3.1) is identified by the - "*expires" identifier. + @signature-params The signature metadata parameters for this + signature. Section 2.4.2 - Its canonicalized value is a Decimal String containing the - signature's Expiration Time expressed as the number of seconds since - the Epoch, as defined in Section 4.16 - (https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/ - V1_chap04.html#tag_04_16) of [POSIX.1]. + Additional specialty content identifiers MAY be defined and + registered in the HTTP Signatures Specialty Content Identifier + Registry. Section 5.3 -2.6. Target Endpoint +2.4.1. Request Target The request target endpoint, consisting of the request method and the path and query of the effective request URI, is identified by the - "*request-target" identifier. + "@request-target" identifier. Its value is canonicalized as follows: 1. Take the lowercased HTTP method of the message. 2. Append a space " ". 3. Append the path and query of the request target of the message, formatted according to the rules defined for the :path pseudo- header in [HTTP2], Section 8.1.2.3. The resulting string is the canonicalized value. -2.6.1. Canonicalization Examples +2.4.1.1. Canonicalization Examples The following table contains non-normative example HTTP messages and - their canonicalized "*request-target" values. + their canonicalized "@request-target" values. +=========================+=================+ - |HTTP Message | *request-target | + |HTTP Message | @request-target | +=========================+=================+ | POST /?param=value HTTP/1.1| post | | Host: www.example.com | /?param=value | +-------------------------+-----------------+ | POST /a/b HTTP/1.1 | post /a/b | | Host: www.example.com | | +-------------------------+-----------------+ | GET http://www.example.com/a/ HTTP/1.1| get /a/ | +-------------------------+-----------------+ | GET http://www.example.com HTTP/1.1| get / | +-------------------------+-----------------+ | CONNECT server.example.com:80 HTTP/1.1| connect / | | Host: server.example.com| | +-------------------------+-----------------+ | OPTIONS * HTTP/1.1 | options * | | Host: server.example.com| | +-------------------------+-----------------+ - Table 4: Non-normative examples of "*request-target" + Table 4: Non-normative examples of "@request-target" canonicalization. +2.4.2. Signature Parameters + + The signature parameters special 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 + with all associated parameters. Section 3.1 + + Note that an HTTP message could contain multiple signatures, but only + the signature parameters used for the current signature are included. + +2.4.2.1. Canonicalization Examples + + Given the following signature parameters: + + +==============+=========================================+ + | Property | Value | + +==============+=========================================+ + | Algorithm | hs2019 | + +--------------+-----------------------------------------+ + | Covered | "@request-target", "host", "date", | + | Content | "cache-control", "x-emptyheader", | + | | "x-example", "x-dictionary;key=b", | + | | "x-dictionary;key=a", "x-list;prefix=3" | + +--------------+-----------------------------------------+ + | Creation | 1402174295 | + | Time | | + +--------------+-----------------------------------------+ + | Expiration | 1402174595 | + | Time | | + +--------------+-----------------------------------------+ + | Verification | The public key provided in | + | Key Material | Appendix B.1.1 and identified by the | + | | "keyid" value "test-key-a". | + +--------------+-----------------------------------------+ + + Table 5 + + The signature parameter value is defined as: + +"@signature-params": ("@request-target" "host" "date" "cache-control" "x-empty-header" "x-example" "x-dictionary";key=b "x-dictionary";key=a "x-list";prefix=3); keyid="test-key-a"; alg="hs2019"; created=1402170695; expires=1402170995 + 3. HTTP Message Signatures An HTTP Message Signature is a signature over a string generated from a subset of the content in an HTTP message and metadata about the signature itself. When successfully verified against an HTTP message, it provides cryptographic proof that with respect to the subset of content that was signed, the message is semantically equivalent to the message for which the signature was generated. 3.1. Signature Metadata HTTP Message Signatures have metadata properties that provide information regarding the signature's generation and/or verification. The following metadata properties are defined: - Algorithm + Algorithm: An HTTP Signature Algorithm defined in the HTTP Signature - Algorithms Registry defined in this document. It describes the - signing and verification algorithms for the signature. - - Creation Time + Algorithms Registry defined in this document, represented as a + string. It describes the signing and verification algorithms for + the signature. + Creation Time: A timestamp representing the point in time that the signature was - generated. Sub-second precision is not supported. A signature's - Creation Time MAY be undefined, indicating that it is unknown. + generated, represented as an integer. Sub-second precision is not + supported. A signature's Creation Time MAY be undefined, + indicating that it is unknown. - Covered Content + Expiration Time: + A timestamp representing the point in time at which the signature + expires, represented as an integer. An expired signature always + fails verification. A signature's Expiration Time MAY be + undefined, indicating that the signature does not expire. + + Verification Key Material: + The key material required to verify the signature. + Covered Content: An ordered list of content identifiers (Section 2) that indicates the metadata and message content that is covered by the signature. - The order of identifiers in this list affects signature generation - and verification, and therefore MUST be preserved. + This list MUST NOT include the "@signature-params" content + identifier. - Expiration Time + The signature metadata is serialized using the rules in [RFC8941] + section 4 as follows: - A timestamp representing the point in time at which the signature - expires. An expired signature always fails verification. A - signature's Expiration Time MAY be undefined, indicating that the - signature does not expire. + 1. Let the output be an empty string. - Verification Key Material + 2. Serialize the content identifiers as an ordered "inner-list" + according to [RFC8941] section 4.1.1.1 and append this to the + output. - The key material required to verify the signature. + 3. Append the signature metadata as parameters according to + [RFC8941] section 4.1.1.2 in the any order, skipping fields that + are not available: + + * "alg": Algorithm as an "sf-string" value. + + * "keyid": Verification Key Material as an "sf-string" value. + + * "created": Creation Time as an "sf-integer" timestamp value. + + * "expires": Expiration Time as an "sf-integer" timestamp value. + + Note that the "inner-list" serialization is used instead of the "sf- + list" serialization in order to facilitate this value's inclusion in + the "Signature-Input" header's dictionary, as discussed in + Section 4.1. + + The Table 6 values would be serialized as follows: + +("@request-target" "host" "date" "cache-control" "x-empty-header" "x-example"); keyid="test-key-a"; alg="hs2019"; created=1402170695; expires=1402170995 3.2. Creating a Signature In order to create a signature, a signer completes the following process: 1. Choose key material and algorithm, and set metadata properties Section 3.2.1 2. Create the Signature Input Section 3.2.2 @@ -649,119 +734,119 @@ 5. The signer creates an ordered list of content identifiers representing the message content and signature metadata to be covered by the signature, and assigns this list as the signature's Covered Content. * Each identifier MUST be one of those defined in Section 2. * This list MUST NOT be empty, as this would result in creating a signature over the empty string. - * If the signature's Algorithm name does not start with rsa, - hmac, or ecdsa, signers SHOULD include "*created" and - "*request-target" in the list. + * Signers SHOULD include "@request-target" in the list. - * If the signature's Algorithm starts with rsa, hmac, or ecdsa, - signers SHOULD include "date" and "*request-target" in the - list. + * Signers SHOULD include a date stamp, such as the "date" + header. Alternatively, the "created" signature metadata + parameter can fulfil this role. * Further guidance on what to include in this list and in what order is out of scope for this document. However, the list order is significant and once established for a given signature it MUST be preserved for that signature. + * Note that the signature metadata is not included in the + explicit list of covered content identifiers since its value + is always covered. + For example, given the following HTTP message: GET /foo HTTP/1.1 Host: example.org Date: Sat, 07 Jun 2014 20:51:35 GMT X-Example: Example header with some whitespace. X-EmptyHeader: X-Dictionary: a=1, b=2 - X-List: (a, b, c, d) + X-List: (a b c d) Cache-Control: max-age=60 Cache-Control: must-revalidate The following table presents a non-normative example of metadata values that a signer may choose: - +==============+================================================+ + +==============+=========================================+ | Property | Value | - +==============+================================================+ + +==============+=========================================+ | Algorithm | hs2019 | - +--------------+------------------------------------------------+ - | Covered | "*request-target", "*created", "host", "date", | - | Content | "cache-contol", "x-emptyheader", "x-example", | - | | "x-dictionary:b", "x-dictionary:a", "x-list:3" | - +--------------+------------------------------------------------+ + +--------------+-----------------------------------------+ + | Covered | "@request-target", "host", "date", | + | Content | "cache-control", "x-emptyheader", | + | | "x-example", "x-dictionary;key=b", | + | | "x-dictionary;key=a", "x-list;prefix=3" | + +--------------+-----------------------------------------+ | Creation | 1402174295 | | Time | | - +--------------+------------------------------------------------+ + +--------------+-----------------------------------------+ | Expiration | 1402174595 | | Time | | - +--------------+------------------------------------------------+ - | Verification | The public key provided in Appendix A.1.1 and | - | Key Material | identified by the "keyId" value "test-key-a". | - +--------------+------------------------------------------------+ + +--------------+-----------------------------------------+ + | Verification | The public key provided in | + | Key Material | Appendix B.1.1 and identified by the | + | | "keyid" value "test-key-a". | + +--------------+-----------------------------------------+ - Table 5: Non-normative example metadata values + Table 6: Non-normative example metadata values 3.2.2. Create the Signature Input The Signature Input is a US-ASCII string containing the content that - will be signed. To create it, the signer concatenates together - entries for each identifier in the signature's Covered Content in the - order it occurs in the list, with each entry separated by a newline - ""\n"". An identifier's entry is a US-ASCII string consisting of the - lowercased identifier followed with a colon "":"", a space "" "", and - the identifier's canonicalized value (described below). - - If Covered Content contains "*created" and the signature's Creation - Time is undefined or the signature's Algorithm name starts with - "rsa", "hmac", or "ecdsa" an implementation MUST produce an error. + will be signed. To create it, the signer or verifier concatenates + together entries for each identifier in the signature's Covered + Content in the order it occurs in the list, with each entry separated + by a newline ""\n"". An identifier's entry is a "sf-string" followed + with a colon "":"", a space "" "", and the identifier's canonicalized + value. - If Covered Content contains "*expires" and the signature does not - have an Expiration Time or the signature's Algorithm name starts with - "rsa", "hmac", or "ecdsa" an implementation MUST produce an error. + The signer or verifier then includes the signature metadata specialty + field "@signature-params" as the last entry in the covered content, + separated by a newline ""\n"". Section 2.4.2 If Covered Content contains an identifier for a header field that is - not present or malformed in the message, the implementation MUST + malformed or is not present in the message, the implementation MUST produce an error. If Covered Content contains an identifier for a Dictionary member - that references a header field that is not present, is malformed in - the message, or is not a Dictionary Structured Field, the - implementation MUST produce an error. If the header field value does - not contain the specified member, the implementation MUST produce an - error. + that references a header field using the "key" parameter that is not + present, is malformed in the message, or is not a Dictionary + Structured Field, the implementation MUST produce an error. If the + header field value does not contain the specified member, the + implementation MUST produce an error. If Covered Content contains an identifier for a List Prefix that - references a header field that is not present, is malformed in the - message, or is not a List Structured Field, the implementation MUST - produce an error. If the header field value contains fewer than the - specified number of members, the implementation MUST produce an - error. + references a header field using the "prefix" parameter that is not + present, is malformed in the message, or is not a List Structured + Field, the implementation MUST produce an error. If the header field + value contains fewer than the specified number of members, the + implementation MUST produce an error. - For the non-normative example Signature metadata in Table 5, the + For the non-normative example Signature metadata in Table 6, the corresponding Signature Input is: - *request-target: get /foo - *created: 1402170695 - host: example.org - date: Tue, 07 Jun 2014 20:51:35 GMT - cache-control: max-age=60, must-revalidate - x-emptyheader: - x-example: Example header with some whitespace. - x-dictionary: b=2 - x-dictionary: a=1 - x-list: (a, b, c) +"@request-target": get /foo +"host": example.org +"date": Tue, 07 Jun 2014 20:51:35 GMT +"cache-control": max-age=60, must-revalidate +"x-emptyheader": +"x-example": Example header with some whitespace. +"x-dictionary";key=b: 2 +"x-dictionary";key=a: 1 +"x-list";prefix=3: (a, b, c) +"@signature-params": ("@request-target" "host" "date" "cache-control" "x-empty-header" "x-example" "x-dictionary";key=b "x-dictionary";key=b "x-list";prefix=3); keyid="test-key-a"; alg="hs2019"; created=1402170695; expires=1402170995 Figure 1: Non-normative example Signature Input 3.2.3. Sign the Signature Input The signer signs the Signature Input using the signing algorithm described by the signature's Algorithm property, and the key material chosen by the signer. The signer then encodes the result of that operation as a base 64-encoded string [RFC4648]. This string is the signature value. @@ -782,21 +867,23 @@ In order to verify a signature, a verifier MUST: 1. Examine the signature's metadata to confirm that the signature meets the requirements described in this document, as well as any additional requirements defined by the application such as which header fields or other content are required to be covered by the signature. 2. Use the received HTTP message and the signature's metadata to recreate the Signature Input, using the process described in - Section 3.2.2. + Section 3.2.2. The value of the "@signature-params" input is the + value of the signature input header field for this signature, not + including the signature's label. 3. Use the signature's Algorithm and Verification Key Material with the recreated Signing Input to verify the signature value. A signature with a Creation Time that is in the future or an Expiration Time that is in the past MUST NOT be processed. The verifier MUST ensure that a signature's Algorithm is appropriate for the key material the verifier will use to verify the signature. If the Algorithm is not appropriate for the key material (for @@ -840,251 +927,204 @@ Message signatures can be included within an HTTP message via the "Signature-Input" and "Signature" HTTP header fields, both defined within this specification. The "Signature" HTTP header field contains signature values, while the "Signature-Input" HTTP header field identifies the Covered Content and metadata that describe how each signature was generated. 4.1. The 'Signature-Input' HTTP Header The "Signature-Input" HTTP header field is a Dictionary Structured - Header [StructuredFields] containing the metadata for zero or more - message signatures generated from content within the HTTP message. - Each member describes a single message signature. The member's name - is an identifier that uniquely identifies the message signature - within the context of the HTTP message. The member's value is the - message signature's Covered Content, expressed as a List of Tokens. - Further signature metadata is expressed in parameters on the member - value, as described below. - -4.1.1. Metadata Parameters - - The parameters on each "Signature-Input" member value contain - metadata about the signature. Each parameter name MUST be a - parameter name registered in the IANA HTTP Signatures Metadata - Parameters Registry defined in Section 5.2 of this document. This - document defines the following parameters, and registers them as the - initial contents of the registry: - - alg - - RECOMMENDED. The "alg" parameter is a Token containing the name - of the signature's Algorithm, as registered in the HTTP Signature - Algorithms Registry defined by this document. Verifiers MUST - determine the signature's Algorithm from the "keyId" parameter - rather than from "alg". If "alg" is provided and differs from or - is incompatible with the algorithm or key material identified by - "keyId" (for example, "alg" has a value of "rsa-sha256" but - "keyId" identifies an EdDSA key), then implementations MUST - produce an error. - - created - - RECOMMENDED. The "created" parameter is a Decimal containing the - signature's Creation Time, expressed as the canonicalized value of - the "*created" content identifier, as defined in Section 2. If - not specified, the signature's Creation Time is undefined. This - parameter is useful when signers are not capable of controlling - the Date HTTP Header such as when operating in certain web browser - environments. - - expires - - OPTIONAL. The "expires" parameter is a Decimal containing the - signature's Expiration Time, expressed as the canonicalized value - of the "*expires" content identifier, as defined in Section 2. If - the signature does not have an Expiration Time, this parameter - MUST be omitted. If not specified, the signature's Expiration - Time is undefined. + Header [RFC8941] containing the metadata for zero or more message + signatures generated from content within the HTTP message. Each + member describes a single message signature. The member's name is an + identifier that uniquely identifies the message signature within the + context of the HTTP message. The member's value is the serialization + of the covered content including all signature metadata parameters, + described in Section 3.1. - keyId + Signature-Input: sig1=("@request-target" "host" "date" + "cache-control" "x-empty-header" "x-example"); keyid="test-key-a"; + alg="hs2019"; created=1402170695; expires=1402170995 - REQUIRED. The "keyId" parameter is a String whose value can be - used by a verifier to identify and/or obtain the signature's - Verification Key Material. Further format and semantics of this - value are out of scope for this document. + To facilitate signature validation, the "Signature-Input" header MUST + contain the same serialization value used in generating the signature + input. 4.2. The 'Signature' HTTP Header The "Signature" HTTP header field is a Dictionary Structured Header - [StructuredFields] containing zero 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 + [RFC8941] containing zero 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=:K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUe\ + Zx/Kdrq32DrfakQ6bPsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibe\ + oHyqU/yCjphSmEdd7WD+zrchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4\ + CaB8X/I5/+HLZLGvDiezqi6/7p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg\ + 1Q7MpWYZs0soHjttq0uLIA3DIbQfLiIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZg\ + FquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==: + 4.3. Examples The following is a non-normative example of "Signature-Input" and "Signature" HTTP header fields representing the signature in Figure 2: - Signature-Input: sig1=(*request-target, *created, host, date, - cache-control, x-empty-header, x-example); keyId="test-key-a"; - alg=hs2019; created=1402170695; expires=1402170995 - Signature: sig1=:K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUe - Zx/Kdrq32DrfakQ6bPsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibe - oHyqU/yCjphSmEdd7WD+zrchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4 - CaB8X/I5/+HLZLGvDiezqi6/7p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg - 1Q7MpWYZs0soHjttq0uLIA3DIbQfLiIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZg + # NOTE: '\' line wrapping per RFC 8792 + + Signature-Input: sig1=("@request-target" "host" "date" + "cache-control" "x-empty-header" "x-example"); keyid="test-key-a"; + alg="hs2019"; created=1402170695; expires=1402170995 + Signature: sig1=:K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUe\ + Zx/Kdrq32DrfakQ6bPsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibe\ + oHyqU/yCjphSmEdd7WD+zrchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4\ + CaB8X/I5/+HLZLGvDiezqi6/7p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg\ + 1Q7MpWYZs0soHjttq0uLIA3DIbQfLiIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZg\ FquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==: Since "Signature-Input" and "Signature" are both defined as Dictionary Structured Headers, they can be used to easily include multiple signatures within the same HTTP message. For example, a signer may include multiple signatures signing the same content with different keys and/or algorithms to support verifiers with different capabilities, or a reverse proxy may include information about the client in header fields when forwarding the request to a service host, and may also include a signature over those fields and the client's signature. The following is a non-normative example of header fields a reverse proxy might add to a forwarded request that contains the signature in the above example: + # NOTE: '\' line wrapping per RFC 8792 + X-Forwarded-For: 192.0.2.123 - Signature-Input: reverse_proxy_sig=(*created, host, date, - signature:sig1, x-forwarded-for); keyId="test-key-a"; - alg=hs2019; created=1402170695; expires=1402170695.25 - Signature: reverse_proxy_sig=:ON3HsnvuoTlX41xfcGWaOEVo1M3bJDRBOp0Pc/O - jAOWKQn0VMY0SvMMWXS7xG+xYVa152rRVAo6nMV7FS3rv0rR5MzXL8FCQ2A35DCEN - LOhEgj/S1IstEAEFsKmE9Bs7McBsCtJwQ3hMqdtFenkDffSoHOZOInkTYGafkoy78 - l1VZvmb3Y4yf7McJwAvk2R3gwKRWiiRCw448Nt7JTWzhvEwbh7bN2swc/v3NJbg/w - JYyYVbelZx4IywuZnYFxgPl/qvqbAjeEVvaLKLgSMr11y+uzxCHoMnDUnTYhMrmOT + Signature-Input: reverse_proxy_sig=("host" "date" + "signature";key=sig1 "x-forwarded-for"); keyid="test-key-a"; + alg="hs2019"; created=1402170695; expires=1402170695 + Signature: reverse_proxy_sig=:ON3HsnvuoTlX41xfcGWaOEVo1M3bJDRBOp0Pc/O\ + jAOWKQn0VMY0SvMMWXS7xG+xYVa152rRVAo6nMV7FS3rv0rR5MzXL8FCQ2A35DCEN\ + LOhEgj/S1IstEAEFsKmE9Bs7McBsCtJwQ3hMqdtFenkDffSoHOZOInkTYGafkoy78\ + l1VZvmb3Y4yf7McJwAvk2R3gwKRWiiRCw448Nt7JTWzhvEwbh7bN2swc/v3NJbg/w\ + JYyYVbelZx4IywuZnYFxgPl/qvqbAjeEVvaLKLgSMr11y+uzxCHoMnDUnTYhMrmOT\ 4O8lBLfRFOcoJPKBdoKg9U0a96U2mUug1bFOozEVYFg==: 5. IANA Considerations 5.1. 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. 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. 5.1.1. Registration Template - Algorithm Name - + 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 - + 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 - + Description: A description of the algorithm used to sign the signing string when generating an HTTP Message Signature, or instructions on how to determine that algorithm. When the description specifies an algorithm, it MUST include a reference to the document or documents that define the algorithm. 5.1.2. Initial Contents (( MS: The references in this section are problematic as many of the specifications that they refer to are too implementation specific, rather than just pointing to the proper signature and hashing specifications. A better approach might be just specifying the signature and hashing function specifications, leaving implementers to connect the dots (which are not that hard to connect). )) 5.1.2.1. hs2019 - Algorithm Name - + Algorithm Name: "hs2019" - Status - + Status: active - Description - - Derived from metadata associated with keyId. Recommend support + Description: + Derived from metadata associated with keyid. Recommend support for: * RSASSA-PSS [RFC8017] using SHA-512 [RFC6234] * HMAC [RFC2104] using SHA-512 [RFC6234] * ECDSA using curve P-256 DSS [FIPS186-4] and SHA-512 [RFC6234] * Ed25519ph, Ed25519ctx, and Ed25519 [RFC8032] 5.1.2.2. rsa-sha1 - Algorithm Name - + Algorithm Name: "rsa-sha1" - Status - + Status: Deprecated; SHA-1 not secure. - Description - + Description: RSASSA-PKCS1-v1_5 [RFC8017] using SHA-1 [RFC6234] 5.1.2.3. rsa-sha256 - Algorithm Name - + Algorithm Name: "rsa-sha256" - Status - + Status: Deprecated; specifying signature algorithm enables attack vector. - Description - + Description: RSASSA-PKCS1-v1_5 [RFC8017] using SHA-256 [RFC6234] 5.1.2.4. hmac-sha256 - Algorithm Name - + Algorithm Name: "hmac-sha256" - Status - + Status: Deprecated; specifying signature algorithm enables attack vector. - Description - + Description: HMAC [RFC2104] using SHA-256 [RFC6234] 5.1.2.5. ecdsa-sha256 - Algorithm Name - + Algorithm Name: "ecdsa-sha256" - Status - + Status: Deprecated; specifying signature algorithm enables attack vector. - Description - + Description: ECDSA using curve P-256 DSS [FIPS186-4] and SHA-256 [RFC6234] 5.2. HTTP Signature Metadata Parameters Registry This document defines the "Signature-Input" Structured Header, whose member values 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. Initial values for this @@ -1094,35 +1134,67 @@ template presented in Section 5.2.1. 5.2.1. Registration Template 5.2.2. 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. - +=========+========+================================+ + +=========+========+==============================+ | Name | Status | Reference(s) | - +=========+========+================================+ - | alg | Active | Section 4.1.1 of this document | - +---------+--------+--------------------------------+ - | created | Active | Section 4.1.1 of this document | - +---------+--------+--------------------------------+ - | expires | Active | Section 4.1.1 of this document | - +---------+--------+--------------------------------+ - | keyId | Active | Section 4.1.1 of this document | - +---------+--------+--------------------------------+ + +=========+========+==============================+ + | alg | Active | Section 3.1 of this document | + +---------+--------+------------------------------+ + | created | Active | Section 3.1 of this document | + +---------+--------+------------------------------+ + | expires | Active | Section 3.1 of this document | + +---------+--------+------------------------------+ + | keyid | Active | Section 3.1 of this document | + +---------+--------+------------------------------+ - Table 6: Initial contents of the HTTP Signature + Table 7: Initial contents of the HTTP Signature Metadata Parameters Registry. +5.3. HTTP Signature Specialty Content Identifiers Registry + + This document defines a method for canonicalizing HTTP message + content, including content that can be generated from the context of + the HTTP message outside of the HTTP headers. This content is + identified by a unique key. IANA is asked to create and maintain a + new registry typed "HTTP Signature Specialty Content Identifiers" to + record and maintain the set of non-header content identifiers and + their canonicalization method. Initial values for this registry are + given in Section 5.3.2. 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. Registration Template + +5.3.2. Initial Contents + + The table below contains the initial contents of the HTTP Signature + Specialty Content Identifiers Registry. + + +===================+========+================================+ + | Name | Status | Reference(s) | + +===================+========+================================+ + | @request-target | Active | Section 2.4.1 of this document | + +-------------------+--------+--------------------------------+ + | @signature-params | Active | Section 2.4.2 of this document | + +-------------------+--------+--------------------------------+ + + Table 8: Initial contents of the HTTP Signature Specialty + Content Identifiers Registry. + 6. 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 to be signed for a given use case. )) There are a number of security considerations to take into account @@ -1135,126 +1207,125 @@ 7.1. Normative References [FIPS186-4] "Digital Signature Standard (DSS)", 2013, . [HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, - . + . [MESSAGING] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, - . + . [POSIX.1] "The Open Group Base Specifications Issue 7, 2018 edition", 2018, . [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- Hashing for Message Authentication", RFC 2104, DOI 10.17487/RFC2104, February 1997, - . + . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, - . + . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, - May 2017, . + May 2017, . + + [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, + . + + [RFC8941] Nottingham, M. and P-H. Kamp, "Structured Field Values for + HTTP", RFC 8941, DOI 10.17487/RFC8941, February 2021, + . [SEMANTICS] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, June 2014, - . - - [StructuredFields] - "Structured Field Vaues for HTTP", 2020, - . + . 7.2. Informative References - [RFC3230] Mogul, J. and A. Van Hoff, "Instance Digests in HTTP", - RFC 3230, DOI 10.17487/RFC3230, January 2002, - . - - [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: - Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, - . - - [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, - . - [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, - . + . [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, - . + . [RFC7239] Petersson, A. and M. Nilsson, "Forwarded HTTP Extension", RFC 7239, DOI 10.17487/RFC7239, June 2014, - . - - [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, - DOI 10.17487/RFC7518, May 2015, - . - - [RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for - HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015, - . + . [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, - . + . [RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital Signature Algorithm (EdDSA)", RFC 8032, DOI 10.17487/RFC8032, January 2017, - . + . [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, - . + . [TLS] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, - . + . [WP-HTTP-Sig-Audit] "Security Considerations for HTTP Signatures", 2013, . -Appendix A. Examples +Appendix A. Detecting HTTP Message Signatures -A.1. Example Keys + There have been many attempts to create signed HTTP messages in the + past, including other non-standard definitions of the "Signature" + header used within this specification. It is recommended that + developers wishing to support both this specification and other + historial drafts do so carefully and deliberately, as + incompatibilities between this specification and various versions of + other drafts could lead to problems. + + It is recommended that implementers first detect and validate the + "Signature-Input" header defined in this specification to detect that + this standard is in use and not an alternative. If the "Signature- + Input" header is present, all "Signature" headers 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. -A.1.1. Example Key RSA test +B.1.1. Example Key RSA test The following key is a 2048-bit RSA public and private key pair: -----BEGIN RSA PUBLIC KEY----- MIIBCgKCAQEAhAKYdtoeoy8zcAcR874L8cnZxKzAGwd7v36APp7Pv6Q2jdsPBRrw WEBnez6d0UDKDwGbc6nxfEXAy5mbhgajzrw3MOEt8uA5txSKobBpKDeBLOsdJKFq MGmXCQvEG7YemcxDTRPxAleIAgYYRjTSd/QBwVW9OwNFhekro3RtlinV0a75jfZg kne/YiktSvLG34lw2zqXBDTC5NHROUqGTlML4PlNZS5Ri2U4aCNx2rUPRcKIlE0P uKxI4T+HIaFpv8+rdV6eUgOrB2xeI1dSFFn/nnv5OoZJEIB+VmuKn3DCUcCZSFlQ PSXSfBDiUGhwOw76WuSSsf1D4b/vLoJ10wIDAQAB @@ -1281,578 +1352,310 @@ 9C+celgZd2PW7aGYLCHq7nPbmfDV0yHcWjOhXZ8jRMjmANVR/eLQ2EfsRLdW69bn f3ZD7JS1fwGnO3exGmHO3HZG+6AvberKYVYNHahNFEw5TsAcQWDLRpkGybBcxqZo 81YCqlqidwfeO5YtlO7etx1xLyqa2NsCeG9A86UjG+aeNnXEIDk1PDK+EuiThIUa /2IxKzJKWl1BKr2d4xAfR0ZnEYuRrbeDQYgTImOlfW6/GuYIxKYgEKCFHFqJATAG IxHrq1PDOiSwXd2GmVVYyEmhZnbcp8CxaEMQoevxAta0ssMK3w6UsDtvUvYvF22m qQKBiD5GwESzsFPy3Ga0MvZpn3D6EJQLgsnrtUPZx+z2Ep2x0xc5orneB5fGyF1P WtP+fG5Q6Dpdz3LRfm+KwBCWFKQjg7uTxcjerhBWEYPmEMKYwTJF5PBG9/ddvHLQ EQeNC8fHGg4UXU8mhHnSBt3EA10qQJfRDs15M38eG2cYwB1PZpDHScDnDA0= -----END RSA PRIVATE KEY----- -A.2. Example keyId Values +B.2. Example keyid Values - The table below maps example "keyId" values to associated algorithms + The table below maps example "keyid" values to associated algorithms and/or keys. These are example mappings that are valid only within the context of examples in examples within this and future documents that reference this section. Unless otherwise specified, within the context of examples it should be assumed that the signer and verifier - understand these "keyId" mappings. These "keyId" values are not + understand these "keyid" mappings. These "keyid" values are not reserved, and deployments are free to use them, with these associations or others. +============+=================================+================+ - | keyId | Algorithm | Verification | + | keyid | Algorithm | Verification | | | | Key | +============+=================================+================+ | test-key-a | "hs2019", using RSASSA-PSS | The public key | | | [RFC8017] and SHA-512 [RFC6234] | specified in | - | | | Appendix A.1.1 | + | | | Appendix B.1.1 | +------------+---------------------------------+----------------+ | test-key-b | rsa-sha256 | The public key | | | | specified in | - | | | Appendix A.1.1 | + | | | Appendix B.1.1 | +------------+---------------------------------+----------------+ - Table 7 + Table 9 -A.3. Test Cases +B.3. Test Cases This section provides non-normative examples that may be used as test cases to validate implementation correctness. These examples are based on the following HTTP message: POST /foo?param=value&pet=dog HTTP/1.1 Host: example.com Date: Tue, 07 Jun 2014 20:51:35 GMT Content-Type: application/json Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE= Content-Length: 18 {"hello": "world"} -A.3.1. Signature Generation +B.3.1. Signature Generation -A.3.1.1. hs2019 signature over minimal recommended content +B.3.1.1. hs2019 signature over minimal recommended content This presents metadata for a Signature using "hs2019", over minimum recommended data to sign: +==============+===================================+ | Property | Value | +==============+===================================+ | Algorithm | "hs2019", using RSASSA-PSS | | | [RFC8017] using SHA-512 [RFC6234] | +--------------+-----------------------------------+ - | Covered | *created, *request-target | + | Covered | @request-target | | Content | | +--------------+-----------------------------------+ | Creation | 8:51:35 PM GMT, June 7th, 2014 | | Time | | +--------------+-----------------------------------+ | Expiration | Undefined | | Time | | +--------------+-----------------------------------+ | Verification | The public key specified in | - | Key Material | Appendix A.1.1. | + | Key Material | Appendix B.1.1. | +--------------+-----------------------------------+ - Table 8 + Table 10 The Signature Input is: - *created: 1402170695 - *request-target: post /foo?param=value&pet=dog +"@request-target": post /foo?param=value&pet=dog +"@signature-params": ("@request-target"); keyid="test-key-a"; created=1402170695 The signature value is: QaVaWYfF2da6tG66Xtd0GrVFChJ0fOWUe/C6kaYESPiYYwnMH9egOgyKqgLLY9NQJFk7b QY834sHEUwjS5ByEBaO3QNwIvqEY1qAAU/2MX14tc9Yn7ELBnaaNHaHkV3xVO9KIuLT7V 6e4OUuGb1axfbXpMgPEql6CEFrn6K95CLuuKP5/gOEcBtmJp5L58gN4VvZrk2OVA6U971 YiEDNuDa4CwMcQMvcGssbc/L3OULTUffD/1VcPtdGImP2uvVQntpT8b2lBeBpfh8MuaV2 vtzidyBYFtAUoYhRWO8+ntqA1q2OK4LMjM2XgDScSVWvGdVd459A0wI9lRlnPap3zg== A possible "Signature-Input" and "Signature" header containing this signature is: - Signature-Input: sig1=(*created, *request-target); - keyId="test-key-a"; created=1402170695 - Signature: sig1=:QaVaWYfF2da6tG66Xtd0GrVFChJ0fOWUe/C6kaYESPiYYwnMH9eg - OgyKqgLLY9NQJFk7bQY834sHEUwjS5ByEBaO3QNwIvqEY1qAAU/2MX14tc9Yn7ELB - naaNHaHkV3xVO9KIuLT7V6e4OUuGb1axfbXpMgPEql6CEFrn6K95CLuuKP5/gOEcB - tmJp5L58gN4VvZrk2OVA6U971YiEDNuDa4CwMcQMvcGssbc/L3OULTUffD/1VcPtd - GImP2uvVQntpT8b2lBeBpfh8MuaV2vtzidyBYFtAUoYhRWO8+ntqA1q2OK4LMjM2X + # NOTE: '\' line wrapping per RFC 8792 + + Signature-Input: sig1=("@request-target"); + keyid="test-key-a"; created=1402170695 + Signature: sig1=:QaVaWYfF2da6tG66Xtd0GrVFChJ0fOWUe/C6kaYESPiYYwnMH9eg\ + OgyKqgLLY9NQJFk7bQY834sHEUwjS5ByEBaO3QNwIvqEY1qAAU/2MX14tc9Yn7ELB\ + naaNHaHkV3xVO9KIuLT7V6e4OUuGb1axfbXpMgPEql6CEFrn6K95CLuuKP5/gOEcB\ + tmJp5L58gN4VvZrk2OVA6U971YiEDNuDa4CwMcQMvcGssbc/L3OULTUffD/1VcPtd\ + GImP2uvVQntpT8b2lBeBpfh8MuaV2vtzidyBYFtAUoYhRWO8+ntqA1q2OK4LMjM2X\ gDScSVWvGdVd459A0wI9lRlnPap3zg==: -A.3.1.2. hs2019 signature covering all header fields +B.3.1.2. hs2019 signature covering all header fields This presents metadata for a Signature using "hs2019" that covers all header fields in the request: - +==============+========================================+ + +==============+============================================+ | Property | Value | - +==============+========================================+ - | Algorithm | "hs2019", using RSASSA-PSS [RFC8017] | - | | using SHA-512 [RFC6234] | - +--------------+----------------------------------------+ - | Covered | *created, *request-target, host, date, | - | Content | content-type, digest, content-length | - +--------------+----------------------------------------+ + +==============+============================================+ + | Algorithm | "hs2019", using RSASSA-PSS [RFC8017] using | + | | SHA-512 [RFC6234] | + +--------------+--------------------------------------------+ + | Covered | "@request-target", "host", "date", | + | Content | "content-type", "digest", "content-length" | + +--------------+--------------------------------------------+ | Creation | 8:51:35 PM GMT, June 7th, 2014 | | Time | | - +--------------+----------------------------------------+ + +--------------+--------------------------------------------+ | Expiration | Undefined | | Time | | - +--------------+----------------------------------------+ + +--------------+--------------------------------------------+ | Verification | The public key specified in | - | Key Material | Appendix A.1.1. | - +--------------+----------------------------------------+ + | Key Material | Appendix B.1.1. | + +--------------+--------------------------------------------+ - Table 9 + Table 11 The Signature Input is: - *created: 1402170695 - *request-target: post /foo?param=value&pet=dog - host: example.com - date: Tue, 07 Jun 2014 20:51:35 GMT - content-type: application/json - digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE= - content-length: 18 +"@request-target": post /foo?param=value&pet=dog +"host": example.com +"date": Tue, 07 Jun 2014 20:51:35 GMT +"content-type": application/json +"digest": SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE= +"content-length": 18 +"@signature-params": ("@request-target" "host" "date" "content-type" "digest" "content-length"); keyid="test-key-a"; alg="hs2019"; created=1402170695 The signature value is: B24UG4FaiE2kSXBNKV4DA91J+mElAhS3mncrgyteAye1GKMpmzt8jkHNjoudtqw3GngGY 3n0mmwjdfn1eA6nAjgeHwl0WXced5tONcCPNzLswqPOiobGeA5y4WE8iBveel30OKYVel 0lZ1OnXOmN5TIEIIPo9LrE+LzZis6A0HA1FRMtKgKGhT3N965pkqfhKbq/V48kpJKT8+c Zs0TOn4HFMG+OIy6c9ofSBrXD68yxP6QYTz6xH0GMWawLyPLYR52j3I05fK1ylAb6K0ox PxzQ5nwrLD+mUVPZ9rDs1En6fmOX9xfkZTblG/5D+s1fHHs9dDXCOVkT5dLS8DjdIA== A possible "Signature-Input" and "Signature" header containing this signature is: - Signature-Input: sig1=(*request-target, *created, host, date, - content-type, digest, content-length); keyId="test-key-a"; - alg=hs2019; created=1402170695 - Signature: sig1=:B24UG4FaiE2kSXBNKV4DA91J+mElAhS3mncrgyteAye1GKMpmzt8 - jkHNjoudtqw3GngGY3n0mmwjdfn1eA6nAjgeHwl0WXced5tONcCPNzLswqPOiobGe - A5y4WE8iBveel30OKYVel0lZ1OnXOmN5TIEIIPo9LrE+LzZis6A0HA1FRMtKgKGhT - 3N965pkqfhKbq/V48kpJKT8+cZs0TOn4HFMG+OIy6c9ofSBrXD68yxP6QYTz6xH0G - MWawLyPLYR52j3I05fK1ylAb6K0oxPxzQ5nwrLD+mUVPZ9rDs1En6fmOX9xfkZTbl + # NOTE: '\' line wrapping per RFC 8792 + + Signature-Input: sig1=("@request-target" "host" "date" + "content-type" "digest" "content-length"); keyid="test-key-a"; + alg="hs2019"; created=1402170695 + Signature: sig1=:B24UG4FaiE2kSXBNKV4DA91J+mElAhS3mncrgyteAye1GKMpmzt8\ + jkHNjoudtqw3GngGY3n0mmwjdfn1eA6nAjgeHwl0WXced5tONcCPNzLswqPOiobGe\ + A5y4WE8iBveel30OKYVel0lZ1OnXOmN5TIEIIPo9LrE+LzZis6A0HA1FRMtKgKGhT\ + 3N965pkqfhKbq/V48kpJKT8+cZs0TOn4HFMG+OIy6c9ofSBrXD68yxP6QYTz6xH0G\ + MWawLyPLYR52j3I05fK1ylAb6K0oxPxzQ5nwrLD+mUVPZ9rDs1En6fmOX9xfkZTbl\ G/5D+s1fHHs9dDXCOVkT5dLS8DjdIA==: -A.3.2. Signature Verification +B.3.2. Signature Verification -A.3.2.1. Minimal Required Signature Header +B.3.2.1. Minimal Required Signature Header This presents a "Signature-Input" and "Signature" header containing only the minimal required parameters: - Signature-Input: sig1=(); keyId="test-key-a"; created=1402170695 - Signature: sig1=:cxieW5ZKV9R9A70+Ua1A/1FCvVayuE6Z77wDGNVFSiluSzR9TYFV - vwUjeU6CTYUdbOByGMCee5q1eWWUOM8BIH04Si6VndEHjQVdHqshAtNJk2Quzs6WC - 2DkV0vysOhBSvFZuLZvtCmXRQfYGTGhZqGwq/AAmFbt5WNLQtDrEe0ErveEKBfaz+ - IJ35zhaj+dun71YZ82b/CRfO6fSSt8VXeJuvdqUuVPWqjgJD4n9mgZpZFGBaDdPiw - pfbVZHzcHrumFJeFHWXH64a+c5GN+TWlP8NPg2zFdEc/joMymBiRelq236WGm5VvV + # NOTE: '\' line wrapping per RFC 8792 + + Signature-Input: sig1=(); keyid="test-key-a"; created=1402170695 + Signature: sig1=:cxieW5ZKV9R9A70+Ua1A/1FCvVayuE6Z77wDGNVFSiluSzR9TYFV\ + vwUjeU6CTYUdbOByGMCee5q1eWWUOM8BIH04Si6VndEHjQVdHqshAtNJk2Quzs6WC\ + 2DkV0vysOhBSvFZuLZvtCmXRQfYGTGhZqGwq/AAmFbt5WNLQtDrEe0ErveEKBfaz+\ + IJ35zhaj+dun71YZ82b/CRfO6fSSt8VXeJuvdqUuVPWqjgJD4n9mgZpZFGBaDdPiw\ + pfbVZHzcHrumFJeFHWXH64a+c5GN+TWlP8NPg2zFdEc/joMymBiRelq236WGm5VvV\ 9a22RW2/yLmaU/uwf9v40yGR/I1NRA==: The corresponding signature metadata derived from this header field is: +=================+==========================================+ | Property | Value | +=================+==========================================+ | Algorithm | "hs2019", using RSASSA-PSS using SHA-256 | +-----------------+------------------------------------------+ - | Covered Content | *created | + | Covered Content | `` | +-----------------+------------------------------------------+ | Creation Time | 8:51:35 PM GMT, June 7th, 2014 | +-----------------+------------------------------------------+ | Expiration Time | Undefined | +-----------------+------------------------------------------+ | Verification | The public key specified in | - | Key Material | Appendix A.1.1. | + | Key Material | Appendix B.1.1. | +-----------------+------------------------------------------+ - Table 10 + Table 12 The corresponding Signature Input is: - *created: 1402170695 +"@signature-params": sig1=(); alg="hs2019"; keyid="test-key-a"; created=1402170695 -A.3.2.2. Minimal Recommended Signature Header +B.3.2.2. Minimal Recommended Signature Header This presents a "Signature-Input" and "Signature" header containing only the minimal required and recommended parameters: - Signature-Input: sig1=(); alg=hs2019; keyId="test-key-a"; + # NOTE: '\' line wrapping per RFC 8792 + + Signature-Input: sig1=(); alg="hs2019"; keyid="test-key-a"; created=1402170695 - Signature: sig1=:cxieW5ZKV9R9A70+Ua1A/1FCvVayuE6Z77wDGNVFSiluSzR9TYFV - vwUjeU6CTYUdbOByGMCee5q1eWWUOM8BIH04Si6VndEHjQVdHqshAtNJk2Quzs6WC - 2DkV0vysOhBSvFZuLZvtCmXRQfYGTGhZqGwq/AAmFbt5WNLQtDrEe0ErveEKBfaz+ - IJ35zhaj+dun71YZ82b/CRfO6fSSt8VXeJuvdqUuVPWqjgJD4n9mgZpZFGBaDdPiw - pfbVZHzcHrumFJeFHWXH64a+c5GN+TWlP8NPg2zFdEc/joMymBiRelq236WGm5VvV + Signature: sig1=:cxieW5ZKV9R9A70+Ua1A/1FCvVayuE6Z77wDGNVFSiluSzR9TYFV\ + vwUjeU6CTYUdbOByGMCee5q1eWWUOM8BIH04Si6VndEHjQVdHqshAtNJk2Quzs6WC\ + 2DkV0vysOhBSvFZuLZvtCmXRQfYGTGhZqGwq/AAmFbt5WNLQtDrEe0ErveEKBfaz+\ + IJ35zhaj+dun71YZ82b/CRfO6fSSt8VXeJuvdqUuVPWqjgJD4n9mgZpZFGBaDdPiw\ + pfbVZHzcHrumFJeFHWXH64a+c5GN+TWlP8NPg2zFdEc/joMymBiRelq236WGm5VvV\ 9a22RW2/yLmaU/uwf9v40yGR/I1NRA==: The corresponding signature metadata derived from this header field is: +=================+==========================================+ | Property | Value | +=================+==========================================+ | Algorithm | "hs2019", using RSASSA-PSS using SHA-512 | +-----------------+------------------------------------------+ - | Covered Content | *created | + | Covered Content | `` | +-----------------+------------------------------------------+ | Creation Time | 8:51:35 PM GMT, June 7th, 2014 | +-----------------+------------------------------------------+ | Expiration Time | Undefined | +-----------------+------------------------------------------+ | Verification | The public key specified in | - | Key Material | Appendix A.1.1. | + | Key Material | Appendix B.1.1. | +-----------------+------------------------------------------+ - Table 11 + Table 13 The corresponding Signature Input is: - *created: 1402170695 + "@signature-params": sig1=(); alg="rsa-sha256"; keyid="test-key-b" -A.3.2.3. Minimal Signature Header using rsa-sha256 +B.3.2.3. Minimal Signature Header using rsa-sha256 This presents a minimal "Signature-Input" and "Signature" header for a signature using the "rsa-sha256" algorithm: - Signature: sig1=(date); alg=rsa-sha256; keyId="test-key-b" - Signature: sig1=:HtXycCl97RBVkZi66ADKnC9c5eSSlb57GnQ4KFqNZplOpNfxqk62 - JzZ484jXgLvoOTRaKfR4hwyxlcyb+BWkVasApQovBSdit9Ml/YmN2IvJDPncrlhPD - VDv36Z9/DiSO+RNHD7iLXugdXo1+MGRimW1RmYdenl/ITeb7rjfLZ4b9VNnLFtVWw - rjhAiwIqeLjodVImzVc5srrk19HMZNuUejK6I3/MyN3+3U8tIRW4LWzx6ZgGZUaEE - P0aBlBkt7Fj0Tt5/P5HNW/Sa/m8smxbOHnwzAJDa10PyjzdIbywlnWIIWtZKPPsoV + # NOTE: '\' line wrapping per RFC 8792 + + Signature: sig1=("date"); alg=rsa-sha256; keyid="test-key-b" + Signature: sig1=:HtXycCl97RBVkZi66ADKnC9c5eSSlb57GnQ4KFqNZplOpNfxqk62\ + JzZ484jXgLvoOTRaKfR4hwyxlcyb+BWkVasApQovBSdit9Ml/YmN2IvJDPncrlhPD\ + VDv36Z9/DiSO+RNHD7iLXugdXo1+MGRimW1RmYdenl/ITeb7rjfLZ4b9VNnLFtVWw\ + rjhAiwIqeLjodVImzVc5srrk19HMZNuUejK6I3/MyN3+3U8tIRW4LWzx6ZgGZUaEE\ + P0aBlBkt7Fj0Tt5/P5HNW/Sa/m8smxbOHnwzAJDa10PyjzdIbywlnWIIWtZKPPsoV\ oKVopUWEU3TNhpWmaVhFrUL/O6SN3w==: The corresponding signature metadata derived from this header field is: +===========================+==========================+ | Property | Value | +===========================+==========================+ | Algorithm | rsa-sha256 | +---------------------------+--------------------------+ | Covered Content | date | +---------------------------+--------------------------+ | Creation Time | Undefined | +---------------------------+--------------------------+ | Expiration Time | Undefined | +---------------------------+--------------------------+ | Verification Key Material | The public key specified | - | | in Appendix A.1.1. | + | | in Appendix B.1.1. | +---------------------------+--------------------------+ - Table 12 + Table 14 The corresponding Signature Input is: - date: Tue, 07 Jun 2014 20:51:35 GMT - -Appendix B. Topics for Working Group Discussion - - _RFC EDITOR: please remove this section before publication_ - - The draft has known issues that will need to be addressed during - development, and these issues have been enumerated but not addressed - in this version. Topics are not listed in any particular order. - -B.1. Issues -B.1.1. Confusing guidance on algorithm and key identification - - The current draft encourages determining the Algorithm metadata - property from the "keyId" field, both in the guidance for the use of - "algorithm" and "keyId", and the definition for the "hs2019" - algorithm and deprecation of the other algorithms in the registry. - The current state arose from concern that a malicious party could - change the value of the "algorithm" parameter, potentially tricking - the verifier into accepting a signature that would not have been - verified under the actual parameter. - - Punting algorithm identification into "keyId" hurts interoperability, - since we aren't defining the syntax or semantics of "keyId". It - actually goes against that claim, as we are dictating that the - signing algorithm must be specified by "keyId" or derivable from it. - It also renders the algorithm registry essentially useless. Instead - of this approach, we can protect against manipulation of the - Signature header field by adding support for (and possibly mandating) - including Signature metadata within the Signature Input. - -B.1.2. Lack of definition of keyId hurts interoperability - - The current text leaves the format and semantics of "keyId" - completely up to the implementation. This is primarily due to the - fact that most implementers of Cavage have extensive investment in - key distribution and management, and just need to plug an identifier - into the header. We should support those cases, but we also need to - provide guidance for the developer that doesn't have that and just - wants to know how to identify a key. It may be enough to punt this - to profiling specs, but this needs to be explored more. - -B.1.3. Algorithm Registry duplicates work of JWA - - [RFC7518] already defines an IANA registry for cryptographic - algorithms. This wasn't used by Cavage out of concerns about - complexity of JOSE, and issues with JWE and JWS being too flexible, - leading to insecure combinations of options. Using JWA's definitions - does not need to mean we're using JOSE, however. We should look at - if/how we can leverage JWA's work without introducing too many sharp - edges for implementers. - - In any use of JWS algorithms, this spec would define a way to create - the JWS Signing Input string to be applied to the algorithm. It - should be noted that this is incompatible with JWS itself, which - requires the inclusion of a structured header in the signature input. - - A possible approach is to incorporate all elements of the JWA - signature algorithm registry into this spec using a prefix or other - marker, such as "jws-RS256" for the RSA 256 JSON Web Signature - algorithm. - -B.1.4. Algorithm Registry should not be initialized with deprecated - entries - - The initial entries in this document reflect those in Cavage. The - ones that are marked deprecated were done so because of the issue - explained in Appendix B.1.1, with the possible exception of "rsa- - sha1". We should probably just remove that one. - -B.1.5. No percent-encoding normalization of path/query - - See: issue #26 (https://github.com/w3c-dvcg/http-signatures/ - issues/26) - - The canonicalization rules for "*request-target" do not perform - handle minor, semantically meaningless differences in percent- - encoding, such that verification could fail if an intermediary - normalizes the effective request URI prior to forwarding the message. - - At a minimum, they should be case and percent-encoding normalized as - described in sections 6.2.2.1 and 6.2.2.2 of [RFC3986]. - -B.1.6. Misleading name for headers parameter - - The Covered Content list contains identifiers for more than just - headers, so the "header" parameter name is no longer appropriate. - Some alternatives: "content", "signed-content", "covered-content". - -B.1.7. Changes to whitespace in header field values break verification - - Some header field values contain RWS, OWS, and/or BWS. Since the - header field value canonicalization rules do not address whitespace, - changes to it (e.g., removing OWS or BWS or replacing strings of RWS - with a single space) can cause verification to fail. - -B.1.8. Multiple Set-Cookie headers are not well supported - - The Set-Cookie header can occur multiple times but does not adhere to - the list syntax, and thus is not well supported by the header field - value concatenation rules. - -B.1.9. Covered Content list is not signed - - The Covered Content list should be part of the Signature Input, to - protect against malicious changes. - -B.1.10. Algorithm is not signed - - The Algorithm should be part of the Signature Input, to protect - against malicious changes. - -B.1.11. Verification key identifier is not signed - - The Verification key identifier (e.g., the value used for the "keyId" - parameter) should be part of the Signature Input, to protect against - malicious changes. - -B.1.12. Max values, precision for Integer String and Decimal String not - defined - - The definitions for Integer String and Decimal String do not specify - a maximum value. The definition for Decimal String (used to provide - sub-second precision for Expiration Time) does not define minimum or - maximum precision requirements. It should set a sane requirement - here (e.g., MUST support up to 3 decimal places and no more). - -B.1.13. keyId parameter value could break list syntax - - The "keyId" parameter value needs to be constrained so as to not - break list syntax (e.g., by containing a comma). - -B.1.14. Creation Time and Expiration Time do not allow for clock skew - - The processing instructions for Creation Time and Expiration Time - imply that verifiers are not permitted to account for clock skew - during signature verification. - -B.1.15. Should require lowercased header field names as identifiers - - The current text allows mixed-case header field names when they are - being used as content identifiers. This is unnecessary, as header - field names are case-insensitive, and creates opportunity for - incompatibility. Instead, content identifiers should always be - lowercase. - -B.1.16. Reconcile Date header and Creation Time - - The draft is missing guidance on if/how the Date header relates to - signature Creation Time. There are cases where they may be - different, such as if a signature was pre-created. Should Creation - Time default to the value in the Date header if the "created" - parameter is not specified? - -B.1.17. Remove algorithm-specific rules for content identifiers - - The rules that restrict when the signer can or must include certain - identifiers appear to be related to the pseudo-revving of the Cavage - draft that happened when the "hs2019" algorithm was introduced. We - should drop these rules, as it can be expected that anyone - implementing this draft will support all content identifiers. - -B.1.18. Add guidance for signing compressed headers - - The draft should provide guidance on how to sign headers when - [RFC7541] is used. This guidance might be as simple as "sign the - uncompressed header field value." - -B.1.19. Transformations to Via header field value break verification - - Intermediaries are permitted to strip comments from the "Via" header - field value, and consolidate related sequences of entries. The - canonicalization rules do not account for these changes, and thus - they cause signature verification to fail if the "Via" header is - signed. At the very least, guidance on signing or not signing "Via" - headers needs to be included. - -B.1.20. Case changes to case-insensitive header field values break - verification - - Some header field values are case-insensitive, in whole or in part. - The canonicalization rules do not account for this, thus a case - change to a covered header field value causes verification to fail. - -B.1.21. Need more examples for Signature header - - Add more examples showing different cases e.g, where "created" or - "expires" are not present. - -B.1.22. Expiration not needed - - In many cases, putting the expiration of the signature into the hands - of the signer opens up more options for failures than necessary. - Instead of the "expires", any verifier can use the "created" field - and an internal lifetime or offset to calculate expiration. We - should consider dropping the "expires" field. - -B.2. Features - -B.2.1. Define more content identifiers - - It should be possible to independently include the following content - and metadata properties in Covered Content: - - * The signature's Algorithm - - * The signature's Covered Content - - * The value used for the "keyId" parameter - - * Request method - - * Individual components of the effective request URI: scheme, - authority, path, query - - * Status code - - * Request body (currently supported via Digest header [RFC3230] ) - -B.2.2. Multiple signature support - - (( Editor's note: I believe this use case is theoretical. Please let - me know if this is a use case you have. )) - - There may be scenarios where attaching multiple signatures to a - single message is useful: - - * A gateway attaches a signature over headers it adds (e.g., - "Forwarded") to messages already signed by the user agent. - - * A signer attaches two signatures signed by different keys, to be - verified by different entities. - - This could be addressed by changing the Signature header syntax to - accept a list of parameter sets for a single signature, e.g., by - separating parameters with "";"" instead of "","". It may also be - necessary to include a signature identifier parameter. - -B.2.3. Support for incremental signing of header field value list items - - (( Editor's note: I believe this use case is theoretical. Please let - me know if this is a use case you have. )) - - Currently, signing a header field value is all-or-nothing: either the - entire value is signed, or none of it is. For header fields that use - list syntax, it would be useful to be able to specify which items in - the list are signed. - - A simple approach that allowed the signer to indicate the list size - at signing time would allow a signer to sign header fields that are - may be appended to by intermediaries as the message makes its way to - the recipient. Specifying list size in terms of number of items - could introduce risks of list syntax is not strictly adhered to - (e.g., a malicious party crafts a value that gets parsed by the - application as 5 items, but by the verifier as 4). Specifying list - size in number of octets might address this, but more exploration is - required. - -B.2.4. Support expected authority changes - - In some cases, the authority of the effective request URI may be - expected to change, for example from "public-service- - name.example.com" to "service-host-1.public-service- - name.example.com". This is commonly the case for services that are - hosted behind a load-balancing gateway, where the client sends - requests to a publicly known domain name for the service, and these - requests are transformed by the gateway into requests to specific - hosts in the service fleet. - - One possible way to handle this would be to special-case the Host - header field to allow verifier to substitute a known expected value, - or a value provided in another header field (e.g., "Via") when - generating the Signature Input, provided that the verifier also - recognizes the real value in the "Host" header. Alternatively, this - logic could apply to an "(audience)" content identifier. - -B.2.5. Support for signing specific cookies - - A signer may only wish to sign one or a few cookies, for example if - the website requires its authentication state cookie to be signed, - but also sets other cookies (e.g., for analytics, ad tracking, etc.) + "date": Tue, 07 Jun 2014 20:51:35 GMT + "@signature-params": ("date"); alg=rsa-sha256; keyid="test-key-b" Acknowledgements - This specification is based on the draft-cavage-http-signatures - draft. The editor would like to thank the authors of that draft, - Mark Cavage and Manu Sporny, for their work on that draft and their - continuing contributions. + 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 editor would also like to thank the following individuals for feedback on and implementations of the draft-cavage-http-signatures draft (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, James H. + Manger, Ilari Liusvaara, 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 @@ -1850,35 +1653,49 @@ 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 - - Since -01 + - Since -02 + + - -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:member-name". + 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:4". + 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.