Signing HTTP Messages
draft-ietf-httpbis-message-signatures-01
The information below is for an old version of the document.
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| Authors | Annabelle Backman , Justin Richer , Manu Sporny | ||
| Last updated | 2020-11-17 | ||
| Replaces | draft-richanna-http-message-signatures, draft-cavage-http-signatures | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-httpbis-message-signatures-01
HTTP A. Backman, Ed.
Internet-Draft Amazon
Intended status: Standards Track J. Richer
Expires: 21 May 2021 Bespoke Engineering
M. Sporny
Digital Bazaar
17 November 2020
Signing HTTP Messages
draft-ietf-httpbis-message-signatures-01
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.
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.
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Copyright Notice
Copyright (c) 2020 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
1.2. HTTP Message Transformations . . . . . . . . . . . . . . 5
1.3. Safe Transformations . . . . . . . . . . . . . . . . . . 6
1.4. Conventions and Terminology . . . . . . . . . . . . . . . 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
2.2.1. 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
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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
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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
1. Introduction
Message integrity and authenticity are important security properties
that are critical to the secure operation of many HTTP applications.
Application developers typically rely on the transport layer to
provide these properties, by operating their application over [TLS].
However, TLS only guarantees these properties over a single TLS
connection, and the path between client and application may be
composed of multiple independent TLS connections (for example, if the
application is hosted behind a TLS-terminating gateway or if the
client is behind a TLS Inspection appliance). In such cases, TLS
cannot guarantee end-to-end message integrity or authenticity between
the client and application. Additionally, some operating
environments present obstacles that make it impractical to use TLS,
or to use features necessary to provide message authenticity.
Furthermore, some applications require the binding of an application-
level key to the HTTP message, separate from any TLS certificates in
use. Consequently, while TLS can meet message integrity and
authenticity needs for many HTTP-based applications, it is not a
universal solution.
This document defines a mechanism for providing end-to-end integrity
and authenticity for content within an HTTP message. The mechanism
allows applications to create digital signatures or message
authentication codes (MACs) over only that content within the message
that is meaningful and appropriate for the application. Strict
canonicalization rules ensure that the verifier can verify the
signature even if the message has been transformed in any of the many
ways permitted by HTTP.
The mechanism described in this document consists of three parts:
* A common nomenclature and canonicalization rule set for the
different protocol elements and other content within HTTP
messages.
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* Algorithms for generating and verifying signatures over HTTP
message content using this nomenclature and rule set.
* A mechanism for attaching a signature and related metadata to an
HTTP message.
1.1. Requirements Discussion
HTTP permits and sometimes requires intermediaries to transform
messages in a variety of ways. This may result in a recipient
receiving a message that is not bitwise equivalent to the message
that was oringally sent. In such a case, the recipient will be
unable to verify a signature over the raw bytes of the sender's HTTP
message, as verifying digital signatures or MACs requires both signer
and verifier to have the exact same signed content. Since the raw
bytes of the message cannot be relied upon as signed content, the
signer and verifier must derive the signed content from their
respective versions of the message, via a mechanism that is resilient
to safe changes that do not alter the meaning of the message.
For a variety of reasons, it is impractical to strictly define what
constitutes a safe change versus an unsafe one. Applications use
HTTP in a wide variety of ways, and may disagree on whether a
particular piece of information in a message (e.g., the body, or the
"Date" header field) is relevant. Thus a general purpose solution
must provide signers with some degree of control over which message
content is signed.
HTTP applications may be running in environments that do not provide
complete access to or control over HTTP messages (such as a web
browser's JavaScript environment), or may be using libraries that
abstract away the details of the protocol (such as the Java
HTTPClient library (https://openjdk.java.net/groups/net/httpclient/
intro.html)). These applications need to be able to generate and
verify signatures despite incomplete knowledge of the HTTP message.
1.2. HTTP Message Transformations
As mentioned earlier, HTTP explicitly permits and in some cases
requires implementations to transform messages in a variety of ways.
Implementations are required to tolerate many of these
transformations. What follows is a non-normative and non-exhaustive
list of transformations that may occur under HTTP, provided as
context:
* Re-ordering of header fields with different header field names
([MESSAGING], Section 3.2.2).
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* Combination of header fields with the same field name
([MESSAGING], Section 3.2.2).
* Removal of header fields listed in the "Connection" header field
([MESSAGING], Section 6.1).
* Addition of header fields that indicate control options
([MESSAGING], Section 6.1).
* Addition or removal of a transfer coding ([MESSAGING],
Section 5.7.2).
* Addition of header fields such as "Via" ([MESSAGING],
Section 5.7.1) and "Forwarded" ([RFC7239], Section 4).
1.3. Safe Transformations
Based on the definition of HTTP and the requirements described above,
we can identify certain types of transformations that should not
prevent signature verification, even when performed on content
covered by the signature. The following list describes those
transformations:
* Combination of header fields with the same field name.
* Reordering of header fields with different names.
* Conversion between different versions of the HTTP protocol (e.g.,
HTTP/1.x to HTTP/2, or vice-versa).
* Changes in casing (e.g., "Origin" to "origin") of any case-
insensitive content such as header field names, request URI
scheme, or host.
* Addition or removal of leading or trailing whitespace to a header
field value.
* Addition or removal of "obs-folds".
* Changes to the "request-target" and "Host" header field that when
applied together do not result in a change to the message's
effective request URI, as defined in Section 5.5 of [MESSAGING].
Additionally, all changes to content not covered by the signature are
considered safe.
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1.4. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The terms "HTTP message", "HTTP request", "HTTP response", "absolute-
form", "absolute-path", "effective request URI", "gateway", "header
field", "intermediary", "request-target", "sender", and "recipient"
are used as defined in [MESSAGING].
The term "method" is to be interpreted as defined in Section 4 of
[SEMANTICS].
For brevity, the term "signature" on its own is used in this document
to refer to both digital signatures and keyed MACs. Similarly, the
verb "sign" refers to the generation of either a digital signature or
keyed MAC over a given input string. The qualified term "digital
signature" refers specifically to the output of an asymmetric
cryptographic signing operation.
In addition to those listed above, this document uses the following
terms:
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
The entity that is generating or has generated an HTTP Message
Signature.
Verifier
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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.
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.
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.
Some content within HTTP messages may 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
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.
2.1. HTTP Header Fields
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.
An HTTP header field value is canonicalized as follows:
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.
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2.1.1. 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. |
+-------------------+----------------------------------+
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.
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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)
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) |
+--------------------+---------------------+
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.
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-B: ()
The following table shows example canonicalized values for different
content identifiers, given those fields:
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+====================+=====================+
| 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 | () |
+--------------------+---------------------+
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.
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].
The use of seconds since the Epoch to canonicalize a timestamp
simplifies processing and avoids timezone management required by
specifications such as [RFC3339].
2.5. Signature Expiration Time
The signature's Expiration Time (Section 3.1) is identified by the
"*expires" identifier.
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].
2.6. Target Endpoint
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.
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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
The following table contains non-normative example HTTP messages and
their canonicalized "*request-target" values.
+=========================+=================+
|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"
canonicalization.
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.
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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
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
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.
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.
Expiration Time
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.
Verification Key Material
The key material required to verify the signature.
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
3. Sign the Signature Input Section 3.2.3
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The following sections describe each of these steps in detail.
3.2.1. Choose and Set Signature Metadata Properties
1. The signer chooses an HTTP Signature Algorithm from those
registered in the HTTP Signature Algorithms Registry defined by
this document, and sets the signature's Algorithm property to
that value. The signer MUST NOT choose an algorithm marked
"Deprecated". The mechanism by which the signer chooses an
algorithm is out of scope for this document.
2. The signer chooses key material to use for signing and
verification, and sets the signature's Verification Key Material
property to the key material required for verification. The
signer MUST choose key material that is appropriate for the
signature's Algorithm, and that conforms to any requirements
defined by the Algorithm, such as key size or format. The
mechanism by which the signer chooses key material is out of
scope for this document.
3. The signer sets the signature's Creation Time property to the
current time.
4. The signer sets the signature's Expiration Time property to the
time at which the signature is to expire, or to undefined if the
signature will not expire.
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.
* If the signature's Algorithm starts with rsa, hmac, or ecdsa,
signers SHOULD include "date" and "*request-target" in the
list.
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* 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.
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)
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" |
+--------------+------------------------------------------------+
| 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". |
+--------------+------------------------------------------------+
Table 5: Non-normative example metadata values
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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.
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.
If Covered Content contains an identifier for a header field that is
not present or malformed 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.
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.
For the non-normative example Signature metadata in Table 5, the
corresponding Signature Input is:
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*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)
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.
For the non-normative example Signature metadata in Section 3.2.1 and
Signature Input in Figure 1, the corresponding signature value is:
K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUeZx/Kdrq32DrfakQ6b
PsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibeoHyqU/yCjphSmEdd7WD+z
rchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4CaB8X/I5/+HLZLGvDiezqi6/7
p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg1Q7MpWYZs0soHjttq0uLIA3DIbQfL
iIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZgFquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==
Figure 2: Non-normative example signature value
3.3. Verifying a Signature
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.
3. Use the signature's Algorithm and Verification Key Material with
the recreated Signing Input to verify the signature value.
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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
example, if it is the wrong size, or in the wrong format), the
signature MUST NOT be processed.
3.3.1. Enforcing Application Requirements
The verification requirements specified in this document are intended
as a baseline set of restrictions that are generally applicable to
all use cases. Applications using HTTP Message Signatures MAY impose
requirements above and beyond those specified by this document, as
appropriate for their use case.
Some non-normative examples of additional requirements an application
might define are:
* Requiring a specific set of header fields to be signed (e.g.,
Authorization, Digest).
* Enforcing a maximum signature age.
* Prohibiting the use of certain algorithms, or mandating the use of
an algorithm.
* Requiring keys to be of a certain size (e.g., 2048 bits vs. 1024
bits).
Application-specific requirements are expected and encouraged. When
an application defines additional requirements, it MUST enforce them
during the signature verification process, and signature verification
MUST fail if the signature does not conform to the application's
requirements.
Applications MUST enforce the requirements defined in this document.
Regardless of use case, applications MUST NOT accept signatures that
do not conform to these requirements.
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4. Including a Message Signature in a Message
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
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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.
keyId
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.
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
member in the HTTP message's "Signature-Input" HTTP header field MUST
be ignored.
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
FquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==:
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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:
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
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
An identifier for the HTTP Signature Algorithm. The name MUST be
an ASCII string consisting only of lower-case characters (""a"" -
""z""), digits (""0"" - ""9""), and hyphens (""-""), and SHOULD
NOT exceed 20 characters in length. The identifier MUST be unique
within the context of the registry.
Status
A brief text description of the status of the algorithm. The
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description MUST begin with one of "Active" or "Deprecated", and
MAY provide further context or explanation as to the reason for
the status.
Description
A 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
"hs2019"
Status
active
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]
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5.1.2.2. rsa-sha1
Algorithm Name
"rsa-sha1"
Status
Deprecated; SHA-1 not secure.
Description
RSASSA-PKCS1-v1_5 [RFC8017] using SHA-1 [RFC6234]
5.1.2.3. rsa-sha256
Algorithm Name
"rsa-sha256"
Status
Deprecated; specifying signature algorithm enables attack vector.
Description
RSASSA-PKCS1-v1_5 [RFC8017] using SHA-256 [RFC6234]
5.1.2.4. hmac-sha256
Algorithm Name
"hmac-sha256"
Status
Deprecated; specifying signature algorithm enables attack vector.
Description
HMAC [RFC2104] using SHA-256 [RFC6234]
5.1.2.5. ecdsa-sha256
Algorithm Name
"ecdsa-sha256"
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Status
Deprecated; specifying signature algorithm enables attack vector.
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
registry are given in Section 5.2.2. Future assignments and
modifications to existing assignments are to be made through the
Expert Review registration policy [RFC8126] and shall follow the
template presented in Section 5.2.1.
5.2.1. 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 |
+---------+--------+--------------------------------+
Table 6: Initial contents of the HTTP Signature
Metadata Parameters Registry.
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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
when implementing or utilizing this specification. A thorough
security analysis of this protocol, including its strengths and
weaknesses, can be found in [WP-HTTP-Sig-Audit].
7. References
7.1. Normative References
[FIPS186-4]
"Digital Signature Standard (DSS)", 2013,
<https://csrc.nist.gov/publications/detail/fips/186/4/
final>.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[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,
<https://www.rfc-editor.org/info/rfc7230>.
[POSIX.1] "The Open Group Base Specifications Issue 7, 2018
edition", 2018,
<https://pubs.opengroup.org/onlinepubs/9699919799/>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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,
<https://www.rfc-editor.org/info/rfc7231>.
[StructuredFields]
"Structured Field Vaues for HTTP", 2020,
<https://datatracker.ietf.org/doc/draft-ietf-httpbis-
header-structure>.
7.2. Informative References
[RFC3230] Mogul, J. and A. Van Hoff, "Instance Digests in HTTP",
RFC 3230, DOI 10.17487/RFC3230, January 2002,
<https://www.rfc-editor.org/info/rfc3230>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[RFC7239] Petersson, A. and M. Nilsson, "Forwarded HTTP Extension",
RFC 7239, DOI 10.17487/RFC7239, June 2014,
<https://www.rfc-editor.org/info/rfc7239>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
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[RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for
HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
<https://www.rfc-editor.org/info/rfc7541>.
[RFC8017] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
"PKCS #1: RSA Cryptography Specifications Version 2.2",
RFC 8017, DOI 10.17487/RFC8017, November 2016,
<https://www.rfc-editor.org/info/rfc8017>.
[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/info/rfc8032>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[TLS] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[WP-HTTP-Sig-Audit]
"Security Considerations for HTTP Signatures", 2013,
<https://web-payments.org/specs/source/http-signatures-
audit/>.
Appendix A. Examples
A.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
The following key is a 2048-bit RSA public and private key pair:
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-----BEGIN RSA PUBLIC KEY-----
MIIBCgKCAQEAhAKYdtoeoy8zcAcR874L8cnZxKzAGwd7v36APp7Pv6Q2jdsPBRrw
WEBnez6d0UDKDwGbc6nxfEXAy5mbhgajzrw3MOEt8uA5txSKobBpKDeBLOsdJKFq
MGmXCQvEG7YemcxDTRPxAleIAgYYRjTSd/QBwVW9OwNFhekro3RtlinV0a75jfZg
kne/YiktSvLG34lw2zqXBDTC5NHROUqGTlML4PlNZS5Ri2U4aCNx2rUPRcKIlE0P
uKxI4T+HIaFpv8+rdV6eUgOrB2xeI1dSFFn/nnv5OoZJEIB+VmuKn3DCUcCZSFlQ
PSXSfBDiUGhwOw76WuSSsf1D4b/vLoJ10wIDAQAB
-----END RSA PUBLIC KEY-----
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
A.2. Example keyId Values
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
reserved, and deployments are free to use them, with these
associations or others.
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+============+=================================+================+
| 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 |
+------------+---------------------------------+----------------+
| test-key-b | rsa-sha256 | The public key |
| | | specified in |
| | | Appendix A.1.1 |
+------------+---------------------------------+----------------+
Table 7
A.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
A.3.1.1. hs2019 signature over minimal recommended content
This presents metadata for a Signature using "hs2019", over minimum
recommended data to sign:
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+==============+===================================+
| Property | Value |
+==============+===================================+
| Algorithm | "hs2019", using RSASSA-PSS |
| | [RFC8017] using SHA-512 [RFC6234] |
+--------------+-----------------------------------+
| Covered | *created, *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. |
+--------------+-----------------------------------+
Table 8
The Signature Input is:
*created: 1402170695
*request-target: post /foo?param=value&pet=dog
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
gDScSVWvGdVd459A0wI9lRlnPap3zg==:
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A.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 |
+--------------+----------------------------------------+
| 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. |
+--------------+----------------------------------------+
Table 9
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
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:
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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
G/5D+s1fHHs9dDXCOVkT5dLS8DjdIA==:
A.3.2. Signature Verification
A.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
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 |
+-----------------+------------------------------------------+
| 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. |
+-----------------+------------------------------------------+
Table 10
The corresponding Signature Input is:
*created: 1402170695
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A.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";
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-512 |
+-----------------+------------------------------------------+
| Covered Content | *created |
+-----------------+------------------------------------------+
| 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. |
+-----------------+------------------------------------------+
Table 11
The corresponding Signature Input is:
*created: 1402170695
A.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:
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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. |
+---------------------------+--------------------------+
Table 12
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
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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.
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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.
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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.
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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.
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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.
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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.)
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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.
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
- Since -01
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".
o Defined content identifiers for first N members of a List,
e.g., "x-list-field:4".
o Fixed up examples.
o Updated introduction now that it's adopted.
- -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.
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- -00
o Initialized from draft-richanna-http-message-signatures-00,
following adoption by the working group.
* draft-richanna-http-message-signatures
- -00
o Converted to xml2rfc v3 and reformatted to comply with RFC
style guides.
o Removed Signature auth-scheme definition and related
content.
o Removed conflicting normative requirements for use of
algorithm parameter. Now MUST NOT be relied upon.
o Removed Extensions appendix.
o Rewrote abstract and introduction to explain context and
need, and challenges inherent in signing HTTP messages.
o Rewrote and heavily expanded algorithm definition, retaining
normative requirements.
o Added definitions for key terms, referenced RFC 7230 for
HTTP terms.
o Added examples for canonicalization and signature generation
steps.
o Rewrote Signature header definition, retaining normative
requirements.
o Added default values for algorithm and expires parameters.
o Rewrote HTTP Signature Algorithms registry definition.
Added change control policy and registry template. Removed
suggested URI.
o Added IANA HTTP Signature Parameter registry.
o Added additional normative and informative references.
o Added Topics for Working Group Discussion section, to be
removed prior to publication as an RFC.
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Authors' Addresses
Annabelle Backman (editor)
Amazon
P.O. Box 81226
Seattle, WA 98108-1226
United States of America
Email: richanna@amazon.com
URI: https://www.amazon.com/
Justin Richer
Bespoke Engineering
Email: ietf@justin.richer.org
URI: https://bspk.io/
Manu Sporny
Digital Bazaar
203 Roanoke Street W.
Blacksburg, VA 24060
United States of America
Email: msporny@digitalbazaar.com
URI: https://manu.sporny.org/
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