draft-ietf-tls-rfc4366-bis-02.txt   draft-ietf-tls-rfc4366-bis-03.txt 
TLS Working Group Donald Eastlake 3rd TLS Working Group Donald Eastlake 3rd
INTERNET-DRAFT Motorola Laboratories INTERNET-DRAFT Eastlake Enterprises
Obsoletes: RFC 4366 Obsoletes: RFC 4366
Intended status: Proposed Standard Intended status: Proposed Standard
Expires: August 2008 February 20, 2008 Expires: April 4, 2009 October 5, 2008
Transport Layer Security (TLS) Extensions: Extension Definitions Transport Layer Security (TLS) Extensions: Extension Definitions
<draft-ietf-tls-rfc4366-bis-02.txt> <draft-ietf-tls-rfc4366-bis-03.txt>
Status of This Document Status of This Document
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Distribution of this document is unlimited. Comments should be sent Distribution of this document is unlimited. Comments should be sent
to the TLS working group mailing list <tls@ietf.org>. to the TLS working group mailing list <tls@ietf.org>.
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Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html http://www.ietf.org/ietf/1id-abstracts.txt
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Abstract Abstract
This document provides documentation for existing specific TLS This document provides documentation for existing specific TLS
extensions. It is a companion document for the TLS 1.2 specification, extensions. It is a companion document for the TLS 1.2 specification
draft-ietf-tls-rfc4346-bis-07.txt. [RFC5246]. The extensions specified are server_name,
max_fragment_length, client_certificate_url, trusted_ca_keys,
truncated_hmac, and status_request.
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Acknowledgements Acknowledgements
This draft is based on material from RFC 4366 for which the authors This draft is based on material from RFC 4366 for which the authors
were S. Blake-Wilson, M. Nystron, D. Hopwood, J. Mikkelsen, and T. were S. Blake-Wilson, M. Nystron, D. Hopwood, J. Mikkelsen, and T.
Wright. Wright.
Table of Contents Table of Contents
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Acknowledgements Acknowledgements
This draft is based on material from RFC 4366 for which the authors This draft is based on material from RFC 4366 for which the authors
were S. Blake-Wilson, M. Nystron, D. Hopwood, J. Mikkelsen, and T. were S. Blake-Wilson, M. Nystron, D. Hopwood, J. Mikkelsen, and T.
Wright. Wright.
Table of Contents Table of Contents
Status of This Document....................................1 Status of This Document....................................1
Abstract...................................................1 Abstract...................................................1
Acknowledgements...........................................2 Acknowledgements...........................................2
Table of Contents..........................................2
1. Introduction............................................3 1. Introduction............................................3
1.1 Specific Extensions Covered............................3 1.1 Specific Extensions Covered............................3
1.2 Conventions Used in This Document......................4 1.2 Conventions Used in This Document......................4
2. Extensions to the Handshake Protocol....................5 2. Extensions to the Handshake Protocol....................5
3. Server Name Indication..................................6 3. Server Name Indication..................................6
4. Maximum Fragment Length Negotiation.....................7 4. Maximum Fragment Length Negotiation.....................8
5. Client Certificate URLs.................................8 5. Client Certificate URLs................................10
6. Trusted CA Indication..................................11 6. Trusted CA Indication..................................13
7. Truncated HMAC.........................................12 7. Truncated HMAC.........................................15
8. Certificate Status Request.............................13 8. Certificate Status Request.............................16
9. Error Alerts...........................................18
9. Error Alerts...........................................16 10. IANA Considerations...................................19
10. IANA Considerations...................................17
11. Security Considerations...............................17
11.1 Security Considerations for server_name..............17
11.2 Security Considerations for max_fragment_length......17
11.3 Security Considerations for client_certificate_url...18
11.4 Security Considerations for trusted_ca_keys..........19
11.5 Security Considerations for truncated_hmac...........19
11.6 Security Considerations for status_request...........20
12. Normative References..................................21 11. Security Considerations...............................19
13. Informative References................................21 11.1 Security Considerations for server_name..............19
11.2 Security Considerations for max_fragment_length......19
11.3 Security Considerations for client_certificate_url...20
11.4 Security Considerations for trusted_ca_keys..........21
11.5 Security Considerations for truncated_hmac...........21
11.6 Security Considerations for status_request...........22
Copyright, Disclaimer, and Additional IPR Provisions......22 12. Normative References..................................23
13. Informative References................................23
Annex A: pkipath MIME Type Registration...................25
Author's Address..........................................23 Copyright, Disclaimer, and Additional IPR Provisions......27
Expiration and File Name..................................23 Author's Address..........................................28
Expiration and File Name..................................28
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1. Introduction 1. Introduction
The TLS (Transport Layer Security) Protocol Version 1.2 is specified The TLS (Transport Layer Security) Protocol Version 1.2 is specified
in [RFCTLS]. That specification includes the framework for extensions in [RFC5246]. That specification includes the framework for
to TLS, considerations in designing such extensions (see Section extensions to TLS, considerations in designing such extensions (see
7.4.1.4 of [RFCTLS]), and IANA Considerations for the allocation of Section 7.4.1.4 of [RFC5246]), and IANA Considerations for the
new extension code points; however, it does not specify any allocation of new extension code points; however, it does not specify
particular extensions other than Signature Algorithms (see Section any particular extensions other than Signature Algorithms (see
7.4.1.4.1 of [RFCTLS]). Section 7.4.1.4.1 of [RFC5246]).
This document provides the specifications for existing TLS This document provides the specifications for existing TLS
extensions. It is, for the most part, the adaptation and editing of extensions. It is, for the most part, the adaptation and editing of
material from [RFC4366], which covered TLS extensions for TLS 1.0 material from [RFC4366], which covered TLS extensions for TLS 1.0
[RFC2246] and TLS 1.1 [RFC4346]. [RFC2246] and TLS 1.1 [RFC4346].
1.1 Specific Extensions Covered 1.1 Specific Extensions Covered
The extensions described here focus on extending the functionality The extensions described here focus on extending the functionality
provided by the TLS protocol message formats. Other issues, such as provided by the TLS protocol message formats. Other issues, such as
the addition of new cipher suites, are deferred. the addition of new cipher suites, are deferred.
The extension types defined in this document are:
enum {
server_name(0), max_fragment_length(1),
client_certificate_url(2), trusted_ca_keys(3),
truncated_hmac(4), status_request(5), (65535)
} ExtensionType;
Specifically, the extensions described in this document: Specifically, the extensions described in this document:
- Allow TLS clients to provide to the TLS server the name of the - Allow TLS clients to provide to the TLS server the name of the
server they are contacting. This functionality is desirable in server they are contacting. This functionality is desirable in
order to facilitate secure connections to servers that host order to facilitate secure connections to servers that host
multiple 'virtual' servers at a single underlying network address. multiple 'virtual' servers at a single underlying network address.
- Allow TLS clients and servers to negotiate the maximum fragment - Allow TLS clients and servers to negotiate the maximum fragment
length to be sent. This functionality is desirable as a result of length to be sent. This functionality is desirable as a result of
memory constraints among some clients, and bandwidth constraints memory constraints among some clients, and bandwidth constraints
among some access networks. among some access networks.
- Allow TLS clients and servers to negotiate the use of client - Allow TLS clients and servers to negotiate the use of client
certificate URLs. This functionality is desirable in order to certificate URLs. This functionality is desirable in order to
conserve memory on constrained clients. conserve memory on constrained clients.
- Allow TLS clients to indicate to TLS servers which CA root keys - Allow TLS clients to indicate to TLS servers which CA root keys
they possess. This functionality is desirable in order to prevent they possess. This functionality is desirable in order to prevent
multiple handshake failures involving TLS clients that are only multiple handshake failures involving TLS clients that are only
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able to store a small number of CA root keys due to memory able to store a small number of CA root keys due to memory
limitations. limitations.
- Allow TLS clients and servers to negotiate the use of truncated - Allow TLS clients and servers to negotiate the use of truncated
MACs. This functionality is desirable in order to conserve MACs. This functionality is desirable in order to conserve
bandwidth in constrained access networks. bandwidth in constrained access networks.
- Allow TLS clients and servers to negotiate that the server sends - Allow TLS clients and servers to negotiate that the server sends
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the client certificate status information (e.g., an Online the client certificate status information (e.g., an Online
Certificate Status Protocol (OCSP) [RFC2560] response) during a Certificate Status Protocol (OCSP) [RFC2560] response) during a
TLS handshake. This functionality is desirable in order to avoid TLS handshake. This functionality is desirable in order to avoid
sending a Certificate Revocation List (CRL) over a constrained sending a Certificate Revocation List (CRL) over a constrained
access network and therefore save bandwidth. access network and therefore save bandwidth.
The extensions described in this document may be used by TLS clients TLS clients and servers may use the extensions described in this
and servers. The extensions are designed to be backwards compatible, document. The extensions are designed to be backwards compatible,
meaning that TLS clients that support the extensions can talk to TLS meaning that TLS clients that support the extensions can talk to TLS
servers that do not support the extensions, and vice versa. servers that do not support the extensions, and vice versa.
1.2 Conventions Used in This Document 1.2 Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
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A server that receives a client hello containing the "server_name" A server that receives a client hello containing the "server_name"
extension MAY use the information contained in the extension to guide extension MAY use the information contained in the extension to guide
its selection of an appropriate certificate to return to the client, its selection of an appropriate certificate to return to the client,
and/or other aspects of security policy. In this event, the server and/or other aspects of security policy. In this event, the server
SHALL include an extension of type "server_name" in the (extended) SHALL include an extension of type "server_name" in the (extended)
server hello. The "extension_data" field of this extension SHALL be server hello. The "extension_data" field of this extension SHALL be
empty. empty.
If the server understood the client hello extension but does not
recognize the server name, it SHOULD send an "unrecognized_name"
alert (which MAY be fatal).
If an application negotiates a server name using an application If an application negotiates a server name using an application
protocol and then upgrades to TLS, and if a server_name extension is protocol and then upgrades to TLS, and if a server_name extension is
sent, then the extension SHOULD contain the same name that was sent, then the extension SHOULD contain the same name that was
negotiated in the application protocol. If the server_name is negotiated in the application protocol. If the server_name is
established in the TLS session handshake, the client SHOULD NOT established in the TLS session handshake, the client SHOULD NOT
attempt to request a different server name at the application layer. attempt to request a different server name at the application layer.
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4. Maximum Fragment Length Negotiation 4. Maximum Fragment Length Negotiation
Without this extension, TLS specifies a fixed maximum plaintext Without this extension, TLS specifies a fixed maximum plaintext
fragment length of 2^14 bytes. It may be desirable for constrained fragment length of 2^14 bytes. It may be desirable for constrained
clients to negotiate a smaller maximum fragment length due to memory clients to negotiate a smaller maximum fragment length due to memory
limitations or bandwidth limitations. limitations or bandwidth limitations.
In order to negotiate smaller maximum fragment lengths, clients MAY In order to negotiate smaller maximum fragment lengths, clients MAY
include an extension of type "max_fragment_length" in the (extended) include an extension of type "max_fragment_length" in the (extended)
client hello. The "extension_data" field of this extension SHALL client hello. The "extension_data" field of this extension SHALL
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Servers that receive an extended client hello containing a Servers that receive an extended client hello containing a
"max_fragment_length" extension MAY accept the requested maximum "max_fragment_length" extension MAY accept the requested maximum
fragment length by including an extension of type fragment length by including an extension of type
"max_fragment_length" in the (extended) server hello. The "max_fragment_length" in the (extended) server hello. The
"extension_data" field of this extension SHALL contain a "extension_data" field of this extension SHALL contain a
"MaxFragmentLength" whose value is the same as the requested maximum "MaxFragmentLength" whose value is the same as the requested maximum
fragment length. fragment length.
If a server receives a maximum fragment length negotiation request If a server receives a maximum fragment length negotiation request
for a value other than the allowed values, it MUST abort the for a value other than the allowed values, it MUST abort the
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handshake with an "illegal_parameter" alert. Similarly, if a client handshake with an "illegal_parameter" alert. Similarly, if a client
receives a maximum fragment length negotiation response that differs receives a maximum fragment length negotiation response that differs
from the length it requested, it MUST also abort the handshake with from the length it requested, it MUST also abort the handshake with
an "illegal_parameter" alert. an "illegal_parameter" alert.
Once a maximum fragment length other than 2^14 has been successfully Once a maximum fragment length other than 2^14 has been successfully
negotiated, the client and server MUST immediately begin fragmenting negotiated, the client and server MUST immediately begin fragmenting
messages (including handshake messages), to ensure that no fragment messages (including handshake messages), to ensure that no fragment
larger than the negotiated length is sent. Note that TLS already larger than the negotiated length is sent. Note that TLS already
requires clients and servers to support fragmentation of handshake requires clients and servers to support fragmentation of handshake
messages. messages.
The negotiated length applies for the duration of the session The negotiated length applies for the duration of the session
including session resumptions. including session resumptions.
The negotiated length limits the input that the record layer may The negotiated length limits the input that the record layer may
process without fragmentation (that is, the maximum value of process without fragmentation (that is, the maximum value of
TLSPlaintext.length; see [RFCTLS], Section 6.2.1). Note that the TLSPlaintext.length; see [RFC5246], Section 6.2.1). Note that the
output of the record layer may be larger. For example, if the output of the record layer may be larger. For example, if the
negotiated length is 2^9=512, then for currently defined cipher negotiated length is 2^9=512, then for currently defined cipher
suites (those defined in [RFCTLS], [RFC2712], and [RFC3268]), and suites (those defined in [RFC5246], [RFC2712], and [RFC3268]), and
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when null compression is used, the record layer output can be at most when null compression is used, the record layer output can be at most
805 bytes: 5 bytes of headers, 512 bytes of application data, 256 805 bytes: 5 bytes of headers, 512 bytes of application data, 256
bytes of padding, and 32 bytes of MAC. This means that in this event bytes of padding, and 32 bytes of MAC. This means that in this event
a TLS record layer peer receiving a TLS record layer message larger a TLS record layer peer receiving a TLS record layer message larger
than 805 bytes may discard the message and send a "record_overflow" than 805 bytes may discard the message and send a "record_overflow"
alert, without decrypting the message. alert, without decrypting the message.
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5. Client Certificate URLs 5. Client Certificate URLs
Without this extension, TLS specifies that when client authentication Without this extension, TLS specifies that when client authentication
is performed, client certificates are sent by clients to servers is performed, client certificates are sent by clients to servers
during the TLS handshake. It may be desirable for constrained clients during the TLS handshake. It may be desirable for constrained clients
to send certificate URLs in place of certificates, so that they do to send certificate URLs in place of certificates, so that they do
not need to store their certificates and can therefore save memory. not need to store their certificates and can therefore save memory.
In order to negotiate sending certificate URLs to a server, clients In order to negotiate sending certificate URLs to a server, clients
MAY include an extension of type "client_certificate_url" in the MAY include an extension of type "client_certificate_url" in the
(extended) client hello. The "extension_data" field of this extension (extended) client hello. The "extension_data" field of this extension
SHALL be empty. SHALL be empty.
(Note that it is necessary to negotiate use of client certificate (Note that it is necessary to negotiate use of client certificate
URLs in order to avoid "breaking" existing TLS servers.) URLs in order to avoid "breaking" existing TLS servers.)
Servers that receive an extended client hello containing a Servers that receive an extended client hello containing a
"client_certificate_url" extension MAY indicate that they are willing "client_certificate_url" extension MAY indicate that they are willing
to accept certificate URLs by including an extension of type to accept certificate URLs by including an extension of type
"client_certificate_url" in the (extended) server hello. The "client_certificate_url" in the (extended) server hello. The
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"extension_data" field of this extension SHALL be empty. "extension_data" field of this extension SHALL be empty.
After negotiation of the use of client certificate URLs has been After negotiation of the use of client certificate URLs has been
successfully completed (by exchanging hellos including successfully completed (by exchanging hellos including
"client_certificate_url" extensions), clients MAY send a "client_certificate_url" extensions), clients MAY send a
"CertificateURL" message in place of a "Certificate" message as "CertificateURL" message in place of a "Certificate" message as
follows (see also Section 2): follows (see also Section 2):
enum { enum {
individual_certs(0), pkipath(1), (255) individual_certs(0), pkipath(1), (255)
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struct { struct {
opaque url<1..2^16-1>; opaque url<1..2^16-1>;
Boolean hash_present; Boolean hash_present;
select (hash_present) { select (hash_present) {
case false: struct {}; case false: struct {};
case true: SHA1Hash; case true: SHA1Hash;
} hash; } hash;
} URLAndOptionalHash; } URLAndOptionalHash;
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opaque SHA1Hash[20]; opaque SHA1Hash[20];
Here "url_and_hash_list" contains a sequence of URLs and optional Here "url_and_hash_list" contains a sequence of URLs and optional
hashes. hashes. Each "url" MUST be an absolute URI reference according to
[RFC3986] that can be immediately used to fetch the certificate(s).
When X.509 certificates are used, there are two possibilities: When X.509 certificates are used, there are two possibilities:
- If CertificateURL.type is "individual_certs", each URL refers to a - If CertificateURL.type is "individual_certs", each URL refers to a
single DER-encoded X.509v3 certificate, with the URL for the client's single DER-encoded X.509v3 certificate, with the URL for the client's
certificate first. certificate first.
- If CertificateURL.type is "pkipath", the list contains a single - If CertificateURL.type is "pkipath", the list contains a single
URL referring to a DER-encoded certificate chain, using the type URL referring to a DER-encoded certificate chain, using the type
PkiPath described in Section 8 of [RFCTLS]. PkiPath described in Annex A.
When any other certificate format is used, the specification that When any other certificate format is used, the specification that
describes use of that format in TLS should define the encoding format describes use of that format in TLS should define the encoding format
of certificates or certificate chains, and any constraint on their of certificates or certificate chains, and any constraint on their
ordering. ordering.
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The hash corresponding to each URL at the client's discretion either The hash corresponding to each URL at the client's discretion either
is not present or is the SHA-1 hash of the certificate or certificate is not present or is the SHA-1 hash of the certificate or certificate
chain (in the case of X.509 certificates, the DER-encoded certificate chain (in the case of X.509 certificates, the DER-encoded certificate
or the DER-encoded PkiPath). or the DER-encoded PkiPath).
Note that when a list of URLs for X.509 certificates is used, the Note that when a list of URLs for X.509 certificates is used, the
ordering of URLs is the same as that used in the TLS Certificate ordering of URLs is the same as that used in the TLS Certificate
message (see [RFCTLS], Section 7.4.2), but opposite to the order in message (see [RFC5246], Section 7.4.2), but opposite to the order in
which certificates are encoded in PkiPath. In either case, the self- which certificates are encoded in PkiPath. In either case, the self-
signed root certificate MAY be omitted from the chain, under the signed root certificate MAY be omitted from the chain, under the
assumption that the server must already possess it in order to assumption that the server must already possess it in order to
validate it. validate it.
Servers receiving "CertificateURL" SHALL attempt to retrieve the Servers receiving "CertificateURL" SHALL attempt to retrieve the
client's certificate chain from the URLs and then process the client's certificate chain from the URLs and then process the
certificate chain as usual. A cached copy of the content of any URL certificate chain as usual. A cached copy of the content of any URL
in the chain MAY be used, provided that a SHA-1 hash is present for in the chain MAY be used, provided that a SHA-1 hash is present for
that URL and it matches the hash of the cached copy. that URL and it matches the hash of the cached copy.
Servers that support this extension MUST support the http: URL scheme Servers that support this extension MUST support the 'http' URI
for certificate URLs, and MAY support other schemes. Use of other scheme for certificate URLs, and MAY support other schemes. Use of
schemes than "http", "https", or "ftp" may create unexpected other schemes than 'http', 'https', or 'ftp' may create unexpected
problems. problems.
If the protocol used is HTTP, then the HTTP server can be configured If the protocol used is HTTP, then the HTTP server can be configured
to use the Cache-Control and Expires directives described in to use the Cache-Control and Expires directives described in
[RFC2616] to specify whether and for how long certificates or [RFC2616] to specify whether and for how long certificates or
certificate chains should be cached. certificate chains should be cached.
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The TLS server is not required to follow HTTP redirects when The TLS server is not required to follow HTTP redirects when
retrieving the certificates or certificate chain. The URLs used in retrieving the certificates or certificate chain. The URLs used in
this extension SHOULD therefore be chosen not to depend on such this extension SHOULD therefore be chosen not to depend on such
redirects. redirects.
If the protocol used to retrieve certificates or certificate chains If the protocol used to retrieve certificates or certificate chains
returns a MIME-formatted response (as HTTP does), then the following returns a MIME-formatted response (as HTTP does), then the following
MIME Content-Types SHALL be used: when a single X.509v3 certificate MIME Content-Types SHALL be used: when a single X.509v3 certificate
is returned, the Content-Type is "application/pkix-cert" [RFC2585], is returned, the Content-Type is "application/pkix-cert" [RFC2585],
and when a chain of X.509v3 certificates is returned, the Content- and when a chain of X.509v3 certificates is returned, the Content-
Type is "application/pkix-pkipath" (see Section 8 of [RFCTLS]). Type is "application/pkix-pkipath" Annex A.
If a SHA-1 hash is present for an URL, then the server MUST check If a SHA-1 hash is present for an URL, then the server MUST check
that the SHA-1 hash of the contents of the object retrieved from that that the SHA-1 hash of the contents of the object retrieved from that
URL (after decoding any MIME Content-Transfer-Encoding) matches the URL (after decoding any MIME Content-Transfer-Encoding) matches the
given hash. If any retrieved object does not have the correct SHA-1 given hash. If any retrieved object does not have the correct SHA-1
hash, the server MUST abort the handshake with a hash, the server MUST abort the handshake with a
bad_certificate_hash_value(114) alert. This alert is always fatal. bad_certificate_hash_value(114) alert. This alert is always fatal.
Clients may choose to send either "Certificate" or "CertificateURL" Clients may choose to send either "Certificate" or "CertificateURL"
after successfully negotiating the option to send certificate URLs. after successfully negotiating the option to send certificate URLs.
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The option to send a certificate is included to provide flexibility The option to send a certificate is included to provide flexibility
to clients possessing multiple certificates. to clients possessing multiple certificates.
If a server encounters an unreasonable delay in obtaining If a server encounters an unreasonable delay in obtaining
certificates in a given CertificateURL, it SHOULD time out and signal certificates in a given CertificateURL, it SHOULD time out and signal
a certificate_unobtainable(111) error alert. This alert MAY be fatal; a certificate_unobtainable(111) error alert. This alert MAY be fatal;
for example, if client authentication is required by the server for for example, if client authentication is required by the server for
the handshake to continue. the handshake to continue.
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6. Trusted CA Indication 6. Trusted CA Indication
Constrained clients that, due to memory limitations, possess only a Constrained clients that, due to memory limitations, possess only a
small number of CA root keys may wish to indicate to servers which small number of CA root keys may wish to indicate to servers which
root keys they possess, in order to avoid repeated handshake root keys they possess, in order to avoid repeated handshake
failures. failures.
In order to indicate which CA root keys they possess, clients MAY In order to indicate which CA root keys they possess, clients MAY
include an extension of type "trusted_ca_keys" in the (extended) include an extension of type "trusted_ca_keys" in the (extended)
client hello. The "extension_data" field of this extension SHALL client hello. The "extension_data" field of this extension SHALL
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} IdentifierType; } IdentifierType;
opaque DistinguishedName<1..2^16-1>; opaque DistinguishedName<1..2^16-1>;
Here "TrustedAuthorities" provides a list of CA root key identifiers Here "TrustedAuthorities" provides a list of CA root key identifiers
that the client possesses. Each CA root key is identified via either: that the client possesses. Each CA root key is identified via either:
- "pre_agreed": no CA root key identity supplied. - "pre_agreed": no CA root key identity supplied.
- "key_sha1_hash": contains the SHA-1 hash of the CA root key. For - "key_sha1_hash": contains the SHA-1 hash of the CA root key. For
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Digital Signature Algorithm (DSA) and Elliptic Curve Digital Digital Signature Algorithm (DSA) and Elliptic Curve Digital
Signature Algorithm (ECDSA) keys, this is the hash of the Signature Algorithm (ECDSA) keys, this is the hash of the
"subjectPublicKey" value. For RSA keys, the hash is of the big- "subjectPublicKey" value. For RSA keys, the hash is of the big-
endian byte string representation of the modulus without any endian byte string representation of the modulus without any
initial 0-valued bytes. (This copies the key hash formats deployed initial 0-valued bytes. (This copies the key hash formats deployed
in other environments.) in other environments.)
- "x509_name": contains the DER-encoded X.509 DistinguishedName of - "x509_name": contains the DER-encoded X.509 DistinguishedName of
the CA. the CA.
- "cert_sha1_hash": contains the SHA-1 hash of a DER-encoded - "cert_sha1_hash": contains the SHA-1 hash of a DER-encoded
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Certificate containing the CA root key. Certificate containing the CA root key.
Note that clients may include none, some, or all of the CA root keys Note that clients may include none, some, or all of the CA root keys
they possess in this extension. they possess in this extension.
Note also that it is possible that a key hash or a Distinguished Name Note also that it is possible that a key hash or a Distinguished Name
alone may not uniquely identify a certificate issuer (for example, if alone may not uniquely identify a certificate issuer (for example, if
a particular CA has multiple key pairs). However, here we assume this a particular CA has multiple key pairs). However, here we assume this
is the case following the use of Distinguished Names to identify is the case following the use of Distinguished Names to identify
certificate issuers in TLS. certificate issuers in TLS.
skipping to change at page 12, line 39 skipping to change at page 15, line 5
The option to include no CA root keys is included to allow the client The option to include no CA root keys is included to allow the client
to indicate possession of some pre-defined set of CA root keys. to indicate possession of some pre-defined set of CA root keys.
Servers that receive a client hello containing the "trusted_ca_keys" Servers that receive a client hello containing the "trusted_ca_keys"
extension MAY use the information contained in the extension to guide extension MAY use the information contained in the extension to guide
their selection of an appropriate certificate chain to return to the their selection of an appropriate certificate chain to return to the
client. In this event, the server SHALL include an extension of type client. In this event, the server SHALL include an extension of type
"trusted_ca_keys" in the (extended) server hello. The "trusted_ca_keys" in the (extended) server hello. The
"extension_data" field of this extension SHALL be empty. "extension_data" field of this extension SHALL be empty.
INTERNET-DRAFT TLS Extension Definitions
7. Truncated HMAC 7. Truncated HMAC
Currently defined TLS cipher suites use the MAC construction HMAC Currently defined TLS cipher suites use the MAC construction HMAC
with either MD5 or SHA-1 [RFC2104] to authenticate record layer with either MD5 or SHA-1 [RFC2104] to authenticate record layer
communications. In TLS, the entire output of the hash function is communications. In TLS, the entire output of the hash function is
used as the MAC tag. However, it may be desirable in constrained used as the MAC tag. However, it may be desirable in constrained
environments to save bandwidth by truncating the output of the hash environments to save bandwidth by truncating the output of the hash
function to 80 bits when forming MAC tags. function to 80 bits when forming MAC tags.
In order to negotiate the use of 80-bit truncated HMAC, clients MAY In order to negotiate the use of 80-bit truncated HMAC, clients MAY
include an extension of type "truncated_hmac" in the extended client include an extension of type "truncated_hmac" in the extended client
hello. The "extension_data" field of this extension SHALL be empty. hello. The "extension_data" field of this extension SHALL be empty.
Servers that receive an extended hello containing a "truncated_hmac" Servers that receive an extended hello containing a "truncated_hmac"
extension MAY agree to use a truncated HMAC by including an extension extension MAY agree to use a truncated HMAC by including an extension
of type "truncated_hmac", with empty "extension_data", in the of type "truncated_hmac", with empty "extension_data", in the
INTERNET-DRAFT TLS Extension Definitions
extended server hello. extended server hello.
Note that if new cipher suites are added that do not use HMAC, and Note that if new cipher suites are added that do not use HMAC, and
the session negotiates one of these cipher suites, this extension the session negotiates one of these cipher suites, this extension
will have no effect. It is strongly recommended that any new cipher will have no effect. It is strongly recommended that any new cipher
suites using other MACs consider the MAC size an integral part of the suites using other MACs consider the MAC size an integral part of the
cipher suite definition, taking into account both security and cipher suite definition, taking into account both security and
bandwidth considerations. bandwidth considerations.
If HMAC truncation has been successfully negotiated during a TLS If HMAC truncation has been successfully negotiated during a TLS
skipping to change at page 13, line 30 skipping to change at page 16, line 5
session, clients and servers MUST use truncated HMACs, calculated as session, clients and servers MUST use truncated HMACs, calculated as
specified in [RFC2104]. That is, SecurityParameters.mac_length is 10 specified in [RFC2104]. That is, SecurityParameters.mac_length is 10
bytes, and only the first 10 bytes of the HMAC output are transmitted bytes, and only the first 10 bytes of the HMAC output are transmitted
and checked. Note that this extension does not affect the calculation and checked. Note that this extension does not affect the calculation
of the pseudo-random function (PRF) as part of handshaking or key of the pseudo-random function (PRF) as part of handshaking or key
derivation. derivation.
The negotiated HMAC truncation size applies for the duration of the The negotiated HMAC truncation size applies for the duration of the
session including session resumptions. session including session resumptions.
INTERNET-DRAFT TLS Extension Definitions
8. Certificate Status Request 8. Certificate Status Request
Constrained clients may wish to use a certificate-status protocol Constrained clients may wish to use a certificate-status protocol
such as OCSP [RFC2560] to check the validity of server certificates, such as OCSP [RFC2560] to check the validity of server certificates,
in order to avoid transmission of CRLs and therefore save bandwidth in order to avoid transmission of CRLs and therefore save bandwidth
on constrained networks. This extension allows for such information on constrained networks. This extension allows for such information
to be sent in the TLS handshake, saving roundtrips and resources. to be sent in the TLS handshake, saving roundtrips and resources.
In order to indicate their desire to receive certificate status In order to indicate their desire to receive certificate status
information, clients MAY include an extension of type information, clients MAY include an extension of type
skipping to change at page 14, line 4 skipping to change at page 16, line 32
CertificateStatusType status_type; CertificateStatusType status_type;
select (status_type) { select (status_type) {
case ocsp: OCSPStatusRequest; case ocsp: OCSPStatusRequest;
} request; } request;
} CertificateStatusRequest; } CertificateStatusRequest;
enum { ocsp(1), (255) } CertificateStatusType; enum { ocsp(1), (255) } CertificateStatusType;
struct { struct {
ResponderID responder_id_list<0..2^16-1>; ResponderID responder_id_list<0..2^16-1>;
INTERNET-DRAFT TLS Extension Definitions
Extensions request_extensions; Extensions request_extensions;
} OCSPStatusRequest; } OCSPStatusRequest;
opaque ResponderID<1..2^16-1>; opaque ResponderID<1..2^16-1>;
opaque Extensions<0..2^16-1>; opaque Extensions<0..2^16-1>;
In the OCSPStatusRequest, the "ResponderIDs" provides a list of OCSP In the OCSPStatusRequest, the "ResponderIDs" provides a list of OCSP
responders that the client trusts. A zero-length "responder_id_list" responders that the client trusts. A zero-length "responder_id_list"
sequence has the special meaning that the responders are implicitly sequence has the special meaning that the responders are implicitly
known to the server, e.g., by prior arrangement. "Extensions" is a known to the server, e.g., by prior arrangement. "Extensions" is a
DER encoding of OCSP request extensions. DER encoding of OCSP request extensions.
Both "ResponderID" and "Extensions" are DER-encoded ASN.1 types as Both "ResponderID" and "Extensions" are DER-encoded ASN.1 types as
defined in [RFC2560]. "Extensions" is imported from [RFC3280]. A defined in [RFC2560]. "Extensions" is imported from [RFC5280]. A
zero-length "request_extensions" value means that there are no zero-length "request_extensions" value means that there are no
extensions (as opposed to a zero-length ASN.1 SEQUENCE, which is not extensions (as opposed to a zero-length ASN.1 SEQUENCE, which is not
valid for the "Extensions" type). valid for the "Extensions" type).
In the case of the "id-pkix-ocsp-nonce" OCSP extension, [RFC2560] is In the case of the "id-pkix-ocsp-nonce" OCSP extension, [RFC2560] is
unclear about its encoding; for clarification, the nonce MUST be a unclear about its encoding; for clarification, the nonce MUST be a
DER-encoded OCTET STRING, which is encapsulated as another OCTET DER-encoded OCTET STRING, which is encapsulated as another OCTET
STRING (note that implementations based on an existing OCSP client STRING (note that implementations based on an existing OCSP client
will need to be checked for conformance to this requirement). will need to be checked for conformance to this requirement).
Servers that receive a client hello containing the "status_request" Servers that receive a client hello containing the "status_request"
INTERNET-DRAFT TLS Extension Definitions
extension MAY return a suitable certificate status response to the extension MAY return a suitable certificate status response to the
client along with their certificate. If OCSP is requested, they client along with their certificate. If OCSP is requested, they
SHOULD use the information contained in the extension when selecting SHOULD use the information contained in the extension when selecting
an OCSP responder and SHOULD include request_extensions in the OCSP an OCSP responder and SHOULD include request_extensions in the OCSP
request. request.
Servers return a certificate response along with their certificate by Servers return a certificate response along with their certificate by
sending a "CertificateStatus" message immediately after the sending a "CertificateStatus" message immediately after the
"Certificate" message (and before any "ServerKeyExchange" or "Certificate" message (and before any "ServerKeyExchange" or
"CertificateRequest" messages). If a server returns a "CertificateRequest" messages). If a server returns a
skipping to change at page 15, line 5 skipping to change at page 17, line 32
struct { struct {
CertificateStatusType status_type; CertificateStatusType status_type;
select (status_type) { select (status_type) {
case ocsp: OCSPResponse; case ocsp: OCSPResponse;
} response; } response;
} CertificateStatus; } CertificateStatus;
opaque OCSPResponse<1..2^24-1>; opaque OCSPResponse<1..2^24-1>;
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An "ocsp_response" contains a complete, DER-encoded OCSP response An "ocsp_response" contains a complete, DER-encoded OCSP response
(using the ASN.1 type OCSPResponse defined in [RFC2560]). Only one (using the ASN.1 type OCSPResponse defined in [RFC2560]). Only one
OCSP response may be sent. OCSP response may be sent.
Note that a server MAY also choose not to send a "CertificateStatus" Note that a server MAY also choose not to send a "CertificateStatus"
message, even if it receives a "status_request" extension in the message, even if has received a "status_request" extension in the
client hello message. client hello message and has sent a "status_request" extension in the
server hello message.
Note in addition that servers MUST NOT send the "CertificateStatus" Note in addition that a server MUST NOT send the "CertificateStatus"
message unless it received a "status_request" extension in the client message unless it received a "status_request" extension in the client
hello message and sent a "status_request" extension in the server
hello message. hello message.
Clients requesting an OCSP response and receiving an OCSP response in Clients requesting an OCSP response and receiving an OCSP response in
a "CertificateStatus" message MUST check the OCSP response and abort a "CertificateStatus" message MUST check the OCSP response and abort
the handshake if the response is not satisfactory with the handshake if the response is not satisfactory with
bad_certificate_status_response(113) alert. This alert is always bad_certificate_status_response(113) alert. This alert is always
fatal. fatal.
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9. Error Alerts 9. Error Alerts
This section defines new error alerts for use with the TLS extensions Four new error alerts are defined for use with the TLS extensions
defined in this document. defined in this document. To avoid "breaking" existing clients and
servers, these alerts MUST NOT be sent unless the sending party has
Four new error alerts are defined. To avoid "breaking" existing received an extended hello message from the party they are
clients and servers, these alerts MUST NOT be sent unless the sending
party has received an extended hello message from the party they are
communicating with. These error alerts are conveyed using the communicating with. These error alerts are conveyed using the
following syntax: following syntax. The new alerts are the last four, as indicated by
the comments on the same line as the error alert number.
enum { enum {
close_notify(0), close_notify(0),
unexpected_message(10), unexpected_message(10),
bad_record_mac(20), bad_record_mac(20),
decryption_failed(21), decryption_failed(21),
record_overflow(22), record_overflow(22),
decompression_failure(30), decompression_failure(30),
handshake_failure(40), handshake_failure(40),
/* 41 is not defined, for historical reasons */ /* 41 is not defined, for historical reasons */
skipping to change at page 17, line 5 skipping to change at page 18, line 50
user_canceled(90), user_canceled(90),
no_renegotiation(100), no_renegotiation(100),
unsupported_extension(110), unsupported_extension(110),
certificate_unobtainable(111), /* new */ certificate_unobtainable(111), /* new */
unrecognized_name(112), /* new */ unrecognized_name(112), /* new */
bad_certificate_status_response(113), /* new */ bad_certificate_status_response(113), /* new */
bad_certificate_hash_value(114), /* new */ bad_certificate_hash_value(114), /* new */
(255) (255)
} AlertDescription; } AlertDescription;
"certificate_unobtainable" is described in Section 5.
"unrecognized_name" is described in Section 3.
"bad_certificate_status_response" is described in Section 8.
"bad_certificate_hash_value" is described in Section 5.
INTERNET-DRAFT TLS Extension Definitions INTERNET-DRAFT TLS Extension Definitions
10. IANA Considerations 10. IANA Considerations
IANA Considerations for TLS Extensions and the creation of a Registry IANA Considerations for TLS Extensions and the creation of a Registry
therefore are all covered in Section 12 of [RFCTLS].. therefore are covered in Section 12 of [RFC5246] except for the
registration of MIME type application/pkix-pkipath. This MIME type
has already been registered but is reproduced in Annex A for
convenience.
The IANA TLS extensions registry entries that reference [RFC4366]
should be updated to reference this document on its publication as an
RFC.
11. Security Considerations 11. Security Considerations
General Security Considerations for TLS Extensions are covered in General Security Considerations for TLS Extensions are covered in
[RFCTLS]. Security Considerations for particular extensions specified [RFC5246]. Security Considerations for particular extensions
in this document are given below. specified in this document are given below.
In general, implementers should continue to monitor the state of the In general, implementers should continue to monitor the state of the
art and address any weaknesses identified. art and address any weaknesses identified.
Additional security considerations are described in the TLS 1.0 RFC Additional security considerations are described in the TLS 1.0 RFC
[RFC2246] and the TLS 1.1 RFC [RFC4346]. [RFC2246] and the TLS 1.1 RFC [RFC4346].
11.1 Security Considerations for server_name 11.1 Security Considerations for server_name
If a single server hosts several domains, then clearly it is If a single server hosts several domains, then clearly it is
necessary for the owners of each domain to ensure that this satisfies necessary for the owners of each domain to ensure that this satisfies
their security needs. Apart from this, server_name does not appear to their security needs. Apart from this, server_name does not appear to
introduce significant security issues. introduce significant security issues.
Implementations MUST ensure that a buffer overflow does not occur, Implementations MUST ensure that a buffer overflow does not occur,
whatever the values of the length fields in server_name. whatever the values of the length fields in server_name.
Although this document specifies an encoding for internationalized
hostnames in the server_name extension, it does not address any
security issues associated with the use of internationalized
hostnames in TLS (in particular, the consequences of "spoofed" names
that are indistinguishable from another name when displayed or
printed). It is recommended that server certificates not be issued
for internationalized hostnames unless procedures are in place to
mitigate the risk of spoofed hostnames.
11.2 Security Considerations for max_fragment_length 11.2 Security Considerations for max_fragment_length
The maximum fragment length takes effect immediately, including for The maximum fragment length takes effect immediately, including for
handshake messages. However, that does not introduce any security handshake messages. However, that does not introduce any security
complications that are not already present in TLS, since TLS requires complications that are not already present in TLS, since TLS requires
implementations to be able to handle fragmented handshake messages. implementations to be able to handle fragmented handshake messages.
Note that as described in Section 4, once a non-null cipher suite has Note that as described in Section 4, once a non-null cipher suite has
been activated, the effective maximum fragment length depends on the
cipher suite and compression method, as well as on the negotiated
INTERNET-DRAFT TLS Extension Definitions INTERNET-DRAFT TLS Extension Definitions
been activated, the effective maximum fragment length depends on the
cipher suite and compression method, as well as on the negotiated
max_fragment_length. This must be taken into account when sizing max_fragment_length. This must be taken into account when sizing
buffers, and checking for buffer overflow. buffers, and checking for buffer overflow.
11.3 Security Considerations for client_certificate_url 11.3 Security Considerations for client_certificate_url
There are two major issues with this extension. There are two major issues with this extension.
The first major issue is whether or not clients should include The first major issue is whether or not clients should include
certificate hashes when they send certificate URLs. certificate hashes when they send certificate URLs.
skipping to change at page 18, line 39 skipping to change at page 20, line 37
issued daily certificates that are stored at a fixed URL and need not issued daily certificates that are stored at a fixed URL and need not
be provided to the client. Clients that choose to omit certificate be provided to the client. Clients that choose to omit certificate
hashes should be aware of the possibility of an attack in which the hashes should be aware of the possibility of an attack in which the
attacker obtains a valid certificate on the client's key that is attacker obtains a valid certificate on the client's key that is
different from the certificate the client intended to provide. different from the certificate the client intended to provide.
Although TLS uses both MD5 and SHA-1 hashes in several other places, Although TLS uses both MD5 and SHA-1 hashes in several other places,
this was not believed to be necessary here. The property required of this was not believed to be necessary here. The property required of
SHA-1 is second pre-image resistance. SHA-1 is second pre-image resistance.
The second major issue is that support for client_certificate_url The second major issue is that support for client_certificate_url
involves the server's acting as a client in another URL protocol. involves the server's acting as a client in another URI scheme
The server therefore becomes subject to many of the same security dependent protocol. The server therefore becomes subject to many of
concerns that clients of the URL scheme are subject to, with the the same security concerns that clients of the URI scheme are subject
added concern that the client can attempt to prompt the server to to, with the added concern that the client can attempt to prompt the
connect to some (possibly weird-looking) URL. server to connect to some (possibly weird-looking) URL.
In general, this issue means that an attacker might use the server to In general, this issue means that an attacker might use the server to
indirectly attack another host that is vulnerable to some security indirectly attack another host that is vulnerable to some security
flaw. It also introduces the possibility of denial of service attacks flaw. It also introduces the possibility of denial of service attacks
in which an attacker makes many connections to the server, each of in which an attacker makes many connections to the server, each of
which results in the server's attempting a connection to the target which results in the server's attempting a connection to the target
of the attack. of the attack.
Note that the server may be behind a firewall or otherwise able to Note that the server may be behind a firewall or otherwise able to
access hosts that would not be directly accessible from the public access hosts that would not be directly accessible from the public
Internet. This could exacerbate the potential security and denial of Internet. This could exacerbate the potential security and denial of
INTERNET-DRAFT TLS Extension Definitions
service problems described above, as well as allow the existence of service problems described above, as well as allow the existence of
internal hosts to be confirmed when they would otherwise be hidden. internal hosts to be confirmed when they would otherwise be hidden.
The detailed security concerns involved will depend on the URL INTERNET-DRAFT TLS Extension Definitions
The detailed security concerns involved will depend on the URI
schemes supported by the server. In the case of HTTP, the concerns schemes supported by the server. In the case of HTTP, the concerns
are similar to those that apply to a publicly accessible HTTP proxy are similar to those that apply to a publicly accessible HTTP proxy
server. In the case of HTTPS, loops and deadlocks may be created, and server. In the case of HTTPS, loops and deadlocks may be created, and
this should be addressed. In the case of FTP, attacks arise that are this should be addressed. In the case of FTP, attacks arise that are
similar to FTP bounce attacks. similar to FTP bounce attacks.
As a result of this issue, it is RECOMMENDED that the As a result of this issue, it is RECOMMENDED that the
client_certificate_url extension should have to be specifically client_certificate_url extension should have to be specifically
enabled by a server administrator, rather than be enabled by default. enabled by a server administrator, rather than be enabled by default.
It is also RECOMMENDED that URI protocols be enabled by the It is also RECOMMENDED that URI schemes be enabled by the
administrator individually, and only a minimal set of protocols be administrator individually, and only a minimal set of schemes be
enabled. Unusual protocols that offer limited security or whose enabled. Unusual protocols that offer limited security or whose
security is not well-understood SHOULD be avoided. security is not well understood SHOULD be avoided.
As discussed in [RFC3986], URLs that specify ports other than the As discussed in [RFC3986], URLs that specify ports other than the
default may cause problems, as may very long URLs (which are more default may cause problems, as may very long URLs (which are more
likely to be useful in exploiting buffer overflow bugs). likely to be useful in exploiting buffer overflow bugs).
Also note that HTTP caching proxies are common on the Internet, and Also note that HTTP caching proxies are common on the Internet, and
some proxies do not check for the latest version of an object some proxies do not check for the latest version of an object
correctly. If a request using HTTP (or another caching protocol) goes correctly. If a request using HTTP (or another caching protocol) goes
through a misconfigured or otherwise broken proxy, the proxy may through a misconfigured or otherwise broken proxy, the proxy may
return an out-of-date response. return an out-of-date response.
skipping to change at page 20, line 4 skipping to change at page 21, line 50
extension, it was not believed necessary to use both MD5 and SHA-1 extension, it was not believed necessary to use both MD5 and SHA-1
hashes. hashes.
11.5 Security Considerations for truncated_hmac 11.5 Security Considerations for truncated_hmac
It is possible that truncated MACs are weaker than "un-truncated" It is possible that truncated MACs are weaker than "un-truncated"
MACs. However, no significant weaknesses are currently known or MACs. However, no significant weaknesses are currently known or
expected to exist for HMAC with MD5 or SHA-1, truncated to 80 bits. expected to exist for HMAC with MD5 or SHA-1, truncated to 80 bits.
Note that the output length of a MAC need not be as long as the Note that the output length of a MAC need not be as long as the
INTERNET-DRAFT TLS Extension Definitions
length of a symmetric cipher key, since forging of MAC values cannot length of a symmetric cipher key, since forging of MAC values cannot
be done off-line: in TLS, a single failed MAC guess will cause the be done off-line: in TLS, a single failed MAC guess will cause the
immediate termination of the TLS session. immediate termination of the TLS session.
INTERNET-DRAFT TLS Extension Definitions
Since the MAC algorithm only takes effect after all handshake Since the MAC algorithm only takes effect after all handshake
messages that affect extension parameters have been authenticated by messages that affect extension parameters have been authenticated by
the hashes in the Finished messages, it is not possible for an active the hashes in the Finished messages, it is not possible for an active
attacker to force negotiation of the truncated HMAC extension where attacker to force negotiation of the truncated HMAC extension where
it would not otherwise be used (to the extent that the handshake it would not otherwise be used (to the extent that the handshake
authentication is secure). Therefore, in the event that any security authentication is secure). Therefore, in the event that any security
problem were found with truncated HMAC in the future, if either the problem were found with truncated HMAC in the future, if either the
client or the server for a given session were updated to take the client or the server for a given session were updated to take the
problem into account, it would be able to veto use of this extension. problem into account, it would be able to veto use of this extension.
skipping to change at page 21, line 27 skipping to change at page 23, line 27
Status Protocol - OCSP", RFC 2560, June 1999. Status Protocol - OCSP", RFC 2560, June 1999.
[RFC2585] Housley, R. and P. Hoffman, "Internet X.509 Public Key [RFC2585] Housley, R. and P. Hoffman, "Internet X.509 Public Key
Infrastructure Operational Protocols: FTP and HTTP", RFC 2585, May Infrastructure Operational Protocols: FTP and HTTP", RFC 2585, May
1999. 1999.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,
L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999. HTTP/1.1", RFC 2616, June 1999.
[RFC3280] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet
X.509 Public Key Infrastructure Certificate and Certificate
Revocation List (CRL) Profile", RFC 3280, April 2002.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January
2005. 2005.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFCTLS] Dierks, T. and E. Rescorla, "The TLS Protocol Version 1.2", [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
draft-ietf-tls-rfc4346-bis-*.txt, March 2007. Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure
Certificate and Certificate Revocation List (CRL) Profile", RFC 5280,
13. Informative References 13. Informative References
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999. RFC 2246, January 1999.
[RFC2712] Medvinsky, A. and M. Hur, "Addition of Kerberos Cipher [RFC2712] Medvinsky, A. and M. Hur, "Addition of Kerberos Cipher
Suites to Transport Layer Security (TLS)", RFC 2712, October 1999. Suites to Transport Layer Security (TLS)", RFC 2712, October 1999.
[RFC3268] Chown, P., "Advanced Encryption Standard (AES) Ciphersuites [RFC3268] Chown, P., "Advanced Encryption Standard (AES) Ciphersuites
for Transport Layer Security (TLS)", RFC 3268, June 2002. for Transport Layer Security (TLS)", RFC 3268, June 2002.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
and T. Wright, "Transport Layer Security (TLS) Extensions", RFC 4366, and T. Wright, "Transport Layer Security (TLS) Extensions", RFC 4366,
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April 2006. April 2006.
[X509-4th] ITU-T Recommendation X.509 (2000) | ISO/IEC 9594-8:2001,
"Information Systems - Open Systems Interconnection - The Directory:
Public key and attribute certificate frameworks."
[X509-4th-TC1] ITU-T Recommendation X.509(2000) Corrigendum 1(2001) |
ISO/IEC 9594-8:2001/Cor.1:2002, Technical Corrigendum 1 to ISO/IEC
9594:8:2001.
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Annex A: pkipath MIME Type Registration
The MIME type application/pkix-pkipath has been registered. A copy
of its template is included here for convenience:
MIME media type name: application
MIME subtype name: pkix-pkipath
Required parameters: none
Optional parameters: version (default value is "1")
Encoding considerations:
This MIME type is a DER encoding of the ASN.1 type PkiPath,
defined as follows:
PkiPath ::= SEQUENCE OF Certificate
PkiPath is used to represent a certification path. Within the
sequence, the order of certificates is such that the subject of
the first certificate is the issuer of the second certificate,
etc.
This is identical to the definition published in [X509-4th-TC1];
note that it is different from that in [X509-4th].
All Certificates MUST conform to [RFC5280]. (This should be
interpreted as a requirement to encode only PKIX-conformant
certificates using this type. It does not necessarily require
that all certificates that are not strictly PKIX-conformant must
be rejected by relying parties, although the security consequences
of accepting any such certificates should be considered
carefully.)
DER (as opposed to BER) encoding MUST be used. If this type is
sent over a 7-bit transport, base64 encoding SHOULD be used.
Security considerations:
The security considerations of [X509-4th] and [RFC5280] (or any
updates to them) apply, as well as those of any protocol that uses
this type (e.g., TLS).
Note that this type only specifies a certificate chain that can be
assessed for validity according to the relying party's existing
configuration of trusted CAs; it is not intended to be used to
specify any change to that configuration.
Interoperability considerations:
No specific interoperability problems are known with this type,
but for recommendations relating to X.509 certificates in general,
see [RFC5280].
Published specification: [RFC4366], and [RFC5280].
INTERNET-DRAFT TLS Extension Definitions
Applications which use this media type: TLS. It may also be used by
other protocols, or for general interchange of PKIX certificate
chains.
Additional information:
Magic number(s): DER-encoded ASN.1 can be easily recognized.
Further parsing is required to distinguish it from other ASN.1
types.
File extension(s): .pkipath
Macintosh File Type Code(s): not specified
Person & email address to contact for further information:
Magnus Nystrom <magnus@rsasecurity.com>
Intended usage: COMMON
Change controller: IESG <iesg@ietf.org>
INTERNET-DRAFT TLS Extension Definitions INTERNET-DRAFT TLS Extension Definitions
Copyright, Disclaimer, and Additional IPR Provisions Copyright, Disclaimer, and Additional IPR Provisions
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
skipping to change at page 23, line 10 skipping to change at page 28, line 10
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
INTERNET-DRAFT TLS Extension Definitions INTERNET-DRAFT TLS Extension Definitions
Author's Address Author's Address
Donald Eastlake 3rd Donald Eastlake 3rd
Motorola Laboratories Eastlake Enterprises
111 Locke Drive 155 Beaver Street
Marlborough, MA 01752 Milford, MA 01757 USA
Tel: +1-508-786-7554 Tel: +1-508-634-2066
Email: Donald.Eastlake@motorola.com Email: d3e3e3@gmail.com
Expiration and File Name Expiration and File Name
This draft expires in August 2008. This draft expires in April 2009.
Its file name is draft-ietf-tls-rfc4366-bis-02.txt. Its file name is draft-ietf-tls-rfc4366-bis-03.txt.
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