Internet DRAFT - draft-cavage-http-signatures
draft-cavage-http-signatures
Network Working Group M. Cavage
Internet-Draft Oracle
Intended status: Standards Track M. Sporny
Expires: April 22, 2020 Digital Bazaar
October 20, 2019
Signing HTTP Messages
draft-cavage-http-signatures-12
Abstract
When communicating over the Internet using the HTTP protocol, it can
be desirable for a server or client to authenticate the sender of a
particular message. It can also be desirable to ensure that the
message was not tampered with during transit. This document
describes a way for servers and clients to simultaneously add
authentication and message integrity to HTTP messages by using a
digital signature.
Feedback
This specification is a joint work product of the W3C Digital
Verification Community Group [1] and the W3C Credentials Community
Group [2]. Feedback related to this specification should logged in
the issue tracker [3] or be sent to public-credentials@w3.org [4].
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
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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 April 22, 2020.
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Copyright Notice
Copyright (c) 2019 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Using Signatures in HTTP Requests . . . . . . . . . . . . 4
1.2. Using Signatures in HTTP Responses . . . . . . . . . . . 4
2. The Components of a Signature . . . . . . . . . . . . . . . . 4
2.1. Signature Parameters . . . . . . . . . . . . . . . . . . 5
2.1.1. keyId . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.2. signature . . . . . . . . . . . . . . . . . . . . . . 5
2.1.3. algorithm . . . . . . . . . . . . . . . . . . . . . . 5
2.1.4. created . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.5. expires . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.6. headers . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Ambiguous Parameters . . . . . . . . . . . . . . . . . . 6
2.3. Signature String Construction . . . . . . . . . . . . . . 7
2.4. Creating a Signature . . . . . . . . . . . . . . . . . . 9
2.5. Verifying a Signature . . . . . . . . . . . . . . . . . . 9
3. The 'Signature' HTTP Authentication Scheme . . . . . . . . . 10
3.1. Authorization Header . . . . . . . . . . . . . . . . . . 10
3.1.1. Initiating Signature Authorization . . . . . . . . . 11
3.1.2. RSA Example . . . . . . . . . . . . . . . . . . . . . 11
3.1.3. HMAC Example . . . . . . . . . . . . . . . . . . . . 12
4. The 'Signature' HTTP Header . . . . . . . . . . . . . . . . . 12
4.1. Signature Header . . . . . . . . . . . . . . . . . . . . 12
4.1.1. RSA Example . . . . . . . . . . . . . . . . . . . . . 13
4.1.2. HMAC Example . . . . . . . . . . . . . . . . . . . . 14
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. Normative References . . . . . . . . . . . . . . . . . . 14
5.2. Informative References . . . . . . . . . . . . . . . . . 14
5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Appendix A. Security Considerations . . . . . . . . . . . . . . 16
Appendix B. Extensions . . . . . . . . . . . . . . . . . . . . . 16
Appendix C. Test Values . . . . . . . . . . . . . . . . . . . . 17
C.1. Default Test . . . . . . . . . . . . . . . . . . . . . . 18
C.2. Basic Test . . . . . . . . . . . . . . . . . . . . . . . 18
C.3. All Headers Test . . . . . . . . . . . . . . . . . . . . 19
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Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 19
Appendix E. IANA Considerations . . . . . . . . . . . . . . . . 20
E.1. Signature Authentication Scheme . . . . . . . . . . . . . 20
E.2. HTTP Signatures Algorithms Registry . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
This protocol extension is intended to provide a simple and standard
way for clients to sign HTTP messages.
HTTP Authentication [RFC2617] defines Basic and Digest authentication
mechanisms, TLS 1.2 [RFC5246] defines cryptographically strong
transport layer security, and OAuth 2.0 [RFC6749] provides a fully-
specified alternative for authorization of web service requests.
Each of these approaches are employed on the Internet today with
varying degrees of protection. However, none of these schemes are
designed to cryptographically sign the HTTP messages themselves,
which is required in order to ensure end-to-end message integrity.
An added benefit of signing the HTTP message for the purposes of end-
to-end message integrity is that the client can be authenticated
using the same mechanism without the need for multiple round-trips.
Several web service providers have invented their own schemes for
signing HTTP messages, but to date, none have been standardized.
While there are no techniques in this proposal that are novel beyond
the previous art, it is useful to standardize a simple and
cryptographically strong mechanism for digitally signing HTTP
messages.
This specification presents two mechanisms with distinct purposes:
1. The "Signature" scheme which is intended primarily to allow a
sender to assert the contents of the message sent are correct and
have not been altered during transmission or storage in a way
that alters the meaning expressed in the original message as
signed. Any party reading the message (the verifier) may
independently confirm the validity of the message signature.
This scheme is agnostic to the client/server direction and can be
used to verify the contents of either HTTP requests, HTTP
reponses, or both.
2. The "Authorization" scheme which is intended primarily to allow a
sender to request access to a resource or resources by proving
that they control a secret key. This specification allows for
this both with a shared secret (using HMAC) or with public/
private keys. The "Authorization" scheme is typically used in
authentication processes and not directly for message signing.
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As a consequence `Authorization` header is normally generated
(and the message signed) by the HTTP client and the message
verified by the HTTP server.
1.1. Using Signatures in HTTP Requests
It is common practice to protect sensitive website and API
functionality via authentication mechanisms. Often, the entity
accessing these APIs is a piece of automated software outside of an
interactive human session. While there are mechanisms like OAuth and
API secrets that are used to grant API access, each have their
weaknesses such as unnecessary complexity for particular use cases or
the use of shared secrets which may not be acceptable to an
implementer. Shared secrets also prohibit any possibility for non-
repudiation, while secure transports such as TLS do not provide for
this at all.
Digital signatures are widely used to provide authentication and
integrity assurances without the need for shared secrets. They also
do not require a round-trip in order to authenticate the client, and
allow the integrity of a message to be verified independently of the
transport (e.g. TLS). A server need only have an understanding of
the key (e.g. through a mapping between the key being used to sign
the content and the authorized entity) to verify that a message was
signed by that entity.
When optionally combined with asymmetric keys associated with an
identity, this specification can also enable authentication of a
client and server with or without prior knowledge of each other.
1.2. Using Signatures in HTTP Responses
HTTP messages are routinely altered as they traverse the
infrastructure of the Internet, for mostly benign reasons. Gateways
and proxies add, remove and alter headers for operational reasons, so
a sender cannot rely on the recipient receiving exactly the message
transmitted. By allowing a sender to sign specified headers, and
recipient or intermediate system can confirm that the original intent
of the sender is preserved, and including a Digest header can also
verify the message body is not modified. This allows any recipient
to easily confirm both the sender's identity, and any incidental or
malicious changes that alter the content or meaning of the message.
2. The Components of a Signature
There are a number of components in a signature that are common
between the 'Signature' HTTP Authentication Scheme and the
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'Signature' HTTP Header. This section details the components of the
digital signature paremeters common to both schemes.
2.1. Signature Parameters
The following section details the Signature Parameters.
2.1.1. keyId
REQUIRED. The `keyId` field is an opaque string that the server can
use to look up the component they need to validate the signature. It
could be an SSH key fingerprint, a URL to machine-readable key data,
an LDAP DN, etc. Management of keys and assignment of `keyId` is out
of scope for this document. Implementations MUST be able to discover
metadata about the key from the `keyId` such that they can determine
the type of digital signature algorithm to employ when creating or
verifying signatures.
2.1.2. signature
REQUIRED. The `signature` parameter is a base 64 encoded digital
signature, as described in RFC 4648 [RFC4648], Section 4 [5]. The
client uses the `algorithm` and `headers` Signature Parameters to
form a canonicalized `signing string`. This `signing string` is then
signed using the key associated with the `keyId` according to its
digital signature algorithm. The `signature` parameter is then set
to the base 64 encoding of the signature.
2.1.3. algorithm
RECOMMENDED. The `algorithm` parameter is used to specify the
signature string construction mechanism. Valid values for this
parameter can be found in the HTTP Signatures Algorithms Registry [6]
and MUST NOT be marked "deprecated". Implementers SHOULD derive the
digital signature algorithm used by an implementation from the key
metadata identified by the `keyId` rather than from this field. If
`algorithm` is provided and differs from the key metadata identified
by the `keyId`, for example `rsa-sha256` but an EdDSA key is
identified via `keyId`, then an implementation MUST produce an error.
Implementers should note that previous versions of the `algorithm`
parameter did not use the key information to derive the digital
signature type and thus could be utilized by attackers to expose
security vulnerabilities.
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2.1.4. created
RECOMMENDED. The `created` field expresses when the signature was
created. The value MUST be a Unix timestamp integer value. A
signature with a `created` timestamp value that is in the future MUST
NOT be processed. Using a Unix timestamp simplifies processing and
avoids timezone management required by specifications such as
RFC3339. Subsecond precision is not supported. This value is useful
when clients are not capable of controlling the `Date` HTTP Header
such as when operating in certain web browser environments.
2.1.5. expires
OPTIONAL. The `expires` field expresses when the signature ceases to
be valid. The value MUST be a Unix timestamp integer value. A
signature with an `expires` timestamp value that is in the past MUST
NOT be processed. Using a Unix timestamp simplifies processing and
avoid timezone management existing in RFC3339. Subsecod precision is
allowed using decimal notation.
2.1.6. headers
OPTIONAL. The `headers` parameter is used to specify the list of
HTTP headers included when generating the signature for the message.
If specified, it SHOULD be a lowercased, quoted list of HTTP header
fields, separated by a single space character. If not specified,
implementations MUST operate as if the field were specified with a
single value, `(created)`, in the list of HTTP headers. Note:
1. The list order is important, and MUST be specified in the order
the HTTP header field-value pairs are concatenated together
during Signature String Construction (Section 2.3) used during
signing and verifying.
2. A zero-length `headers` parameter value MUST NOT be used, since
it results in a signature of an empty string.
2.2. Ambiguous Parameters
If any of the parameters listed above are erroneously duplicated in
the associated header field, then the the signature MUST NOT be
processed. Any parameter that is not recognized as a parameter, or
is not well-formed, MUST be ignored.
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2.3. Signature String Construction
A signed HTTP message needs to be tolerant of some trivial
alterations during transmission as it goes through gateways, proxies,
and other entities. These changes are often of little consequence
and very benign, but also often not visible to or detectable by
either the sender or the recipient. Simply signing the entire
message that was transmitted by the sender is therefore not feasible:
Even very minor changes would result in a signature which cannot be
verified.
This specification allows the sender to select which headers are
meaningful by including their names in the `headers` Signature
Parameter. The headers appearing in this parameter are then used to
construct the intermediate Signature String, which is the data that
is actually signed.
In order to generate the string that is signed with a key, the client
MUST use the values of each HTTP header field in the `headers`
Signature Parameter, in the order they appear in the `headers`
Signature Parameter. It is out of scope for this document to dictate
what header fields an application will want to enforce, but
implementers SHOULD at minimum include the `(request-target)` and
`(created)` header fields if `algorithm` does not start with `rsa`,
`hmac`, or `ecdsa`. Otherwise, `(request-target)` and `date` SHOULD
be included in the signature.
To include the HTTP request target in the signature calculation, use
the special `(request-target)` header field name. To include the
signature creation time, use the special `(created)` header field
name. To include the signature expiration time, use the special
`(expires)` header field name.
1. If the header field name is `(request-target)` then generate the
header field value by concatenating the lowercased :method, an
ASCII space, and the :path pseudo-headers (as specified in
HTTP/2, Section 8.1.2.3 [7]). Note: For the avoidance of doubt,
lowercasing only applies to the :method pseudo-header and not to
the :path pseudo-header.
2. If the header field name is `(created)` and the `algorithm`
parameter starts with `rsa`, `hmac`, or `ecdsa` an implementation
MUST produce an error. If the `created` Signature Parameter is
not specified, or is not an integer, an implementation MUST
produce an error. Otherwise, the header field value is the
integer expressed by the `created` signature parameter.
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3. If the header field name is `(expires)` and the `algorithm`
parameter starts with `rsa`, `hmac`, or `ecdsa` an implementation
MUST produce an error. If the `expires` Signature Parameter is
not specified, or is not an integer, an implementation MUST
produce an error. Otherwise, the header field value is the
integer expressed by the `created` signature parameter.
4. Create the header field string by concatenating the lowercased
header field name followed with an ASCII colon `:`, an ASCII
space ` `, and the header field value. Leading and trailing
optional whitespace (OWS) in the header field value MUST be
omitted (as specified in RFC7230 [RFC7230], Section 3.2.4 [8]).
1. If there are multiple instances of the same header field, all
header field values associated with the header field MUST be
concatenated, separated by a ASCII comma and an ASCII space
`, `, and used in the order in which they will appear in the
transmitted HTTP message.
2. If the header value (after removing leading and trailing
whitespace) is a zero-length string, the signature string
line correlating with that header will simply be the
(lowercased) header name, an ASCII colon `:`, and an ASCII
space ` `.
3. Any other modification to the header field value MUST NOT be
made.
4. If a header specified in the headers parameter is malformed
or cannot be matched with a provided header in the message,
the implementation MUST produce an error.
5. If value is not the last value then append an ASCII newline `\n`.
To illustrate the rules specified above, assume a `headers` parameter
list with the value of `(request-target) (created) host date cache-
control x-emptyheader x-example` with the following HTTP request
headers:
GET /foo HTTP/1.1
Host: example.org
Date: Tue, 07 Jun 2014 20:51:35 GMT
X-Example: Example header
with some whitespace.
X-EmptyHeader:
Cache-Control: max-age=60
Cache-Control: must-revalidate
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For the HTTP request headers above, the corresponding signature
string is:
(request-target): get /foo
(created): 1402170695
host: example.org
date: Tue, 07 Jun 2014 20:51:35 GMT
cache-control: max-age=60, must-revalidate
x-emptyheader:
x-example: Example header with some whitespace.
2.4. Creating a Signature
In order to create a signature, a client MUST:
1. Use the `headers` and `algorithm` values as well as the contents
of the HTTP message, to create the signature string.
2. Use the key associated with `keyId` to generate a digital
signature on the signature string.
3. The `signature` is then generated by base 64 encoding the output
of the digital signature algorithm.
For example, assume that the `algorithm` value is "hs2019" and the
`keyId` refers to an EdDSA public key. This would signal to the
application that the signature string construction mechanism is the
one defined in Section 2.3: Signature String Construction [9], the
signature string hashing function is SHA-512, and the signing
algorithm is Ed25519 as defined in RFC 8032 [RFC8032], Section 5.1:
Ed25519ph, Ed25519ctx, and Ed25519. The result of the signature
creation algorithm should result in a binary string, which is then
base 64 encoded and placed into the `signature` value.
2.5. Verifying a Signature
In order to verify a signature, a server MUST:
1. Use the received HTTP message, the `headers` value, and the
Signature String Construction (Section 2.3) algorithm to recreate
the signature.
2. The `algorithm`, `keyId`, and base 64 decoded `signature` listed
in the Signature Parameters are then used to verify the
authenticity of the digital signature. Note: The application
verifying the signature MUST derive the digital signature
algorithm from the metadata associated with the `keyId` and MUST
NOT use the value of `algorithm` from the signed message.
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If a header specified in the `headers` value of the Signature
Parameters (or the default item `(created)` where the `headers` value
is not supplied) is absent from the message, the implementation MUST
produce an error.
For example, assume that the `algorithm` value was "hs2019" and and
the `keyId` refers to an EdDSA public key. This would signal to the
application that the signature string construction mechanism is the
one defined in Section 2.3: Signature String Construction [10], the
signature string hashing function is SHA-512, and the signing
algorithm is Ed25519 as defined in RFC 8032 [RFC8032], Section 5.1:
Ed25519ph, Ed25519ctx, and Ed25519. The result of the signature
verification algorithm should result in a successful verification
unless the headers protected by the signature were tampered with in
transit.
3. The 'Signature' HTTP Authentication Scheme
The "Signature" authentication scheme is based on the model that the
client must authenticate itself with a digital signature produced by
either a private asymmetric key (e.g., RSA) or a shared symmetric key
(e.g., HMAC).
The scheme is parameterized enough such that it is not bound to any
particular key type or signing algorithm.
3.1. Authorization Header
The client is expected to send an Authorization header (as defined in
RFC 7235 [RFC7235], Section 4.1 [11]) where the "auth-scheme" is
"Signature" and the "auth-param" parameters meet the requirements
listed in Section 2: The Components of a Signature.
The rest of this section uses the following HTTP request as an
example.
POST /foo HTTP/1.1
Host: example.org
Date: Tue, 07 Jun 2014 20:51:35 GMT
Content-Type: application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18
{"hello": "world"}
Note that the use of the `Digest` header field is per RFC 3230
[RFC3230], Section 4.3.2 [12] and is included merely as a
demonstration of how an implementer could include information about
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the body of the message in the signature. The following sections
also assume that the "rsa-key-1" keyId asserted by the client is an
identifier meaningful to the server.
3.1.1. Initiating Signature Authorization
A server may notify a client when a resource is protected by
requiring a signature. To initiate this process, the server will
request that the client authenticate itself via a 401 response [13]
code. The server may optionally specify which HTTP headers it
expects to be signed by specifying the `headers` parameter in the
WWW-Authenticate header. For example:
HTTP/1.1 401 Unauthorized
Date: Thu, 08 Jun 2014 18:32:30 GMT
Content-Length: 1234
Content-Type: text/html
WWW-Authenticate: Signature
realm="Example",headers="(request-target) (created)"
...
3.1.2. RSA Example
The authorization header and signature would be generated as:
Authorization: Signature keyId="rsa-key-1",algorithm="hs2019",
headers="(request-target) (created) host digest content-length",
signature="Base64(RSA-SHA512(signing string))"
The client would compose the signing string as:
(request-target): post /foo\n
(created): 1402174295
host: example.org\n
digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=\n
content-length: 18
Note that the '\n' symbols above are included to demonstrate where
the new line character should be inserted. There is no new line on
the final line of the signing string. Each HTTP header above is
displayed on a new line to provide better readability of the example.
For an RSA-based signature, the authorization header and signature
would then be generated as:
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Authorization: Signature keyId="rsa-key-1",algorithm="hs2019",
headers="(request-target) (created) host digest content-length",
signature="Base64(RSA-SHA512(signing string))"
3.1.3. HMAC Example
For an HMAC-based signature without a list of headers specified, the
authorization header and signature would be generated as:
Authorization: Signature keyId="hmac-key-1",algorithm="hs2019",
headers="(request-target) (created) host digest content-length",
signature="Base64(HMAC-SHA512(signing string))"
The only difference between the RSA Example and the HMAC Example is
the digital signature algorithm that is used. The client would
compose the signing string in the same way as the RSA Example above:
(request-target): post /foo\n
(created): 1402174295
host: example.org\n
digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=\n
content-length: 18
4. The 'Signature' HTTP Header
The "Signature" HTTP Header provides a mechanism to link the headers
of a message (client request or server response) to a digital
signature. By including the "Digest" header with a properly
formatted digest, the message body can also be linked to the
signature. The signature is generated and verified either using a
shared secret (e.g. HMAC) or public/private keys (e.g. RSA, EC).
This allows the receiver and/or any intermediate system to
immediately or later verify the integrity of the message. When the
signature is generated with a private key it can also provide a
measure of non-repudiation, though a full implementation of a non-
repudiatable statement is beyond the scope of this specification and
highly dependent on implementation.
The "Signature" scheme can also be used for authentication similar to
the purpose of the 'Signature' HTTP Authentication Scheme
(Section 3). The scheme is parameterized enough such that it is not
bound to any particular key type or signing algorithm.
4.1. Signature Header
The sender is expected to transmit a header (as defined in RFC 7230
[RFC7230], Section 3.2 [14]) where the "field-name" is "Signature",
and the "field-value" contains one or more "auth-param"s (as defined
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in RFC 7235 [RFC7235], Section 4.1 [15]) where the "auth-param"
parameters meet the requirements listed in Section 2: The Components
of a Signature.
The rest of this section uses the following HTTP request as an
example.
POST /foo HTTP/1.1
Host: example.org
Date: Tue, 07 Jun 2014 20:51:35 GMT
Content-Type: application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18
{"hello": "world"}
The following sections assume that the "rsa-key-1" keyId provided by
the signer is an identifier meaningful to the server.
4.1.1. RSA Example
The signature header and signature would be generated as:
Signature: keyId="rsa-key-1",algorithm="hs2019",
created=1402170695, expires=1402170995,
headers="(request-target) (created) (expires)
host date digest content-length",
signature="Base64(RSA-SHA256(signing string))"
The client would compose the signing string as:
(request-target): post /foo\n
(created): 1402170695
(expires): 1402170995
host: example.org\n
digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=\n
content-length: 18
Note that the '\n' symbols above are included to demonstrate where
the new line character should be inserted. There is no new line on
the final line of the signing string. Each HTTP header above is
displayed on a new line to provide better readability of the example.
For an RSA-based signature, the authorization header and signature
would then be generated as:
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Signature: keyId="rsa-key-1",algorithm="hs2019",created=1402170695,
headers="(request-target) (created) host digest content-length",
signature="Base64(RSA-SHA512(signing string))"
4.1.2. HMAC Example
For an HMAC-based signature without a list of headers specified, the
authorization header and signature would be generated as:
Signature: keyId="hmac-key-1",algorithm="hs2019",created=1402170695,
headers="(request-target) (created) host digest content-length",
signature="Base64(HMAC-SHA512(signing string))"
The only difference between the RSA Example and the HMAC Example is
the signature algorithm that is used. The client would compose the
signing string in the same way as the RSA Example above:
(request-target): post /foo\n
(created): 1402170695
host: example.org\n
digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=\n
content-length: 18
5. References
5.1. Normative References
[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>.
[RFC7230] 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>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc7235>.
5.2. Informative References
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication",
RFC 2617, DOI 10.17487/RFC2617, June 1999,
<https://www.rfc-editor.org/info/rfc2617>.
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[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>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[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>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[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>.
5.3. URIs
[1] https://w3c-dvcg.github.io/
[2] https://w3c-ccg.github.io/
[3] https://github.com/w3c-dvcg/http-signatures/issues
[4] mailto:public-credentials@w3.org
[5] https://tools.ietf.org/html/rfc4648#section-4
[6] #hsa-registry
[7] https://tools.ietf.org/html/rfc7540#section-8.1.2.3
[8] https://tools.ietf.org/html/rfc7230#section-3.2.4
[9] #canonicalization
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[10] #canonicalization
[11] https://tools.ietf.org/html/rfc7235#section-2.1
[12] https://tools.ietf.org/html/rfc3230#section-4.3.2
[13] https://tools.ietf.org/html/rfc7235#section-3.1
[14] https://tools.ietf.org/html/rfc7230#section-3.2
[15] https://tools.ietf.org/html/rfc7235#section-4.1
[16] https://web-payments.org/specs/source/http-signatures-audit/
[17] https://web-payments.org/specs/source/http-signature-nonces/
[18] https://web-payments.org/specs/source/http-signature-trailers/
[19] https://www.iana.org/assignments/http-auth-scheme-signature
[20] https://www.iana.org/assignments/http-authschemes
[21] https://www.iana.org/assignments/shm-algorithms
[22] #canonicalization
[23] #canonicalization
[24] #canonicalization
[25] #canonicalization
[26] #canonicalization
Appendix A. Security Considerations
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 Security Considerations for HTTP
Signatures [16].
Appendix B. Extensions
This specification was designed to be simple, modular, and
extensible. There are a number of other specifications that build on
this one. For example, the HTTP Signature Nonces [17] specification
details how to use HTTP Signatures over a non-secured channel like
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HTTP and the HTTP Signature Trailers [18] specification explains how
to apply HTTP Signatures to streaming content. Developers that
desire more functionality than this specification provides are urged
to ensure that an extension specification doesn't already exist
before implementing a proprietary extension.
If extensions to this specification are made by adding new Signature
Parameters, those extension parameters MUST be registered in the
Signature Authentication Scheme Registry. The registry will be
created and maintained at (the suggested URI)
https://www.iana.org/assignments/http-auth-scheme-signature [19]. An
example entry in this registry is included below:
Signature Parameter: nonce
Reference to specification: [HTTP_AUTH_SIGNATURE_NONCE], Section XYZ.
Notes (optional): The HTTP Signature Nonces specification details
how to use HTTP Signatures over a unsecured channel like HTTP.
Appendix C. Test Values
WARNING: THESE TEST VECTORS ARE OLD AND POSSIBLY WRONG. THE NEXT
VERSION OF THIS SPECIFICATION WILL CONTAIN THE PROPER TEST VECTORS.
The following test data uses the following RSA 2048-bit keys, which
we will refer to as `keyId=Test` in the following samples:
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDCFENGw33yGihy92pDjZQhl0C3
6rPJj+CvfSC8+q28hxA161QFNUd13wuCTUcq0Qd2qsBe/2hFyc2DCJJg0h1L78+6
Z4UMR7EOcpfdUE9Hf3m/hs+FUR45uBJeDK1HSFHD8bHKD6kv8FPGfJTotc+2xjJw
oYi+1hqp1fIekaxsyQIDAQAB
-----END PUBLIC KEY-----
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
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All examples use this request:
POST /foo?param=value&pet=dog HTTP/1.1
Host: example.com
Date: Sun, 05 Jan 2014 21:31:40 GMT
Content-Type: application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18
{"hello": "world"}
C.1. Default Test
If a list of headers is not included, the date is the only header
that is signed by default for rsa-sha256. The string to sign would
be:
date: Sun, 05 Jan 2014 21:31:40 GMT
The Authorization header would be:
Authorization: Signature keyId="Test",algorithm="rsa-sha256",
signature="SjWJWbWN7i0wzBvtPl8rbASWz5xQW6mcJmn+ibttBqtifLN7Sazz
6m79cNfwwb8DMJ5cou1s7uEGKKCs+FLEEaDV5lp7q25WqS+lavg7T8hc0GppauB
6hbgEKTwblDHYGEtbGmtdHgVCk9SuS13F0hZ8FD0k/5OxEPXe5WozsbM="
The Signature header would be:
Signature: keyId="Test",algorithm="rsa-sha256",
signature="SjWJWbWN7i0wzBvtPl8rbASWz5xQW6mcJmn+ibttBqtifLN7Sazz
6m79cNfwwb8DMJ5cou1s7uEGKKCs+FLEEaDV5lp7q25WqS+lavg7T8hc0GppauB
6hbgEKTwblDHYGEtbGmtdHgVCk9SuS13F0hZ8FD0k/5OxEPXe5WozsbM="
C.2. Basic Test
The minimum recommended data to sign is the (request-target), host,
and date. In this case, the string to sign would be:
(request-target): post /foo?param=value&pet=dog
host: example.com
date: Sun, 05 Jan 2014 21:31:40 GMT
The Authorization header would be:
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Authorization: Signature keyId="Test",algorithm="rsa-sha256",
headers="(request-target) host date",
signature="qdx+H7PHHDZgy4y/Ahn9Tny9V3GP6YgBPyUXMmoxWtLbHpUnXS
2mg2+SbrQDMCJypxBLSPQR2aAjn7ndmw2iicw3HMbe8VfEdKFYRqzic+efkb3
nndiv/x1xSHDJWeSWkx3ButlYSuBskLu6kd9Fswtemr3lgdDEmn04swr2Os0="
C.3. All Headers Test
A strong signature including all of the headers and a digest of the
body of the HTTP request would result in the following signing
string:
(request-target): post /foo?param=value&pet=dog
host: example.com
date: Sun, 05 Jan 2014 21:31:40 GMT
content-type: application/json
digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
content-length: 18
The Authorization header would be:
Authorization: Signature keyId="Test",algorithm="rsa-sha256",
created=1402170695, expires=1402170699,
headers="(request-target) (created) (expires)
host date content-type digest content-length",
signature="vSdrb+dS3EceC9bcwHSo4MlyKS59iFIrhgYkz8+oVLEEzmYZZvRs
8rgOp+63LEM3v+MFHB32NfpB2bEKBIvB1q52LaEUHFv120V01IL+TAD48XaERZF
ukWgHoBTLMhYS2Gb51gWxpeIq8knRmPnYePbF5MOkR0Zkly4zKH7s1dE="
The Signature header would be:
Signature: keyId="Test",algorithm="rsa-sha256",
created=1402170695, expires=1402170699,
headers="(request-target) (created) (expires)
host date content-type digest content-length",
signature="vSdrb+dS3EceC9bcwHSo4MlyKS59iFIrhgYkz8+oVLEEzmYZZvRs
8rgOp+63LEM3v+MFHB32NfpB2bEKBIvB1q52LaEUHFv120V01IL+TAD48XaERZF
ukWgHoBTLMhYS2Gb51gWxpeIq8knRmPnYePbF5MOkR0Zkly4zKH7s1dE="
Appendix D. Acknowledgements
The editor would like to thank the following individuals for feedback
on and implementations of the specification (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,
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Julian Reschke, Michael Richardson, Wojciech Rygielski, Adam Scarr,
Cory J. Slep, Dirk Stein, Henry Story, Lukasz Szewc, Chris Webber,
and Jeffrey Yasskin
Appendix E. IANA Considerations
E.1. Signature Authentication Scheme
The following entry should be added to the Authentication Scheme
Registry located at https://www.iana.org/assignments/http-authschemes
[20]
Authentication Scheme Name: Signature
Reference: [RFC_THIS_DOCUMENT], Section 2.
Notes (optional): The Signature scheme is designed for clients to
authenticate themselves with a server.
E.2. HTTP Signatures Algorithms Registry
The following initial entries should be added to the Canonicalization
Algorithms Registry to be created and maintained at (the suggested
URI) https://www.iana.org/assignments/shm-algorithms [21]:
Editor's note: 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).
Algorithm Name: hs2019
Status: active
Canonicalization Algorithm: [RFC_THIS_DOCUMENT], Section 2.3:
Signature String Construction [22]
Hash Algorithm: RFC 6234 [RFC6234], SHA-512 (SHA-2 with 512-bits of
digest output)
Digital Signature Algorithm: Derived from metadata associated with
`keyId`. Recommend support for RFC 8017 [RFC8017], Section 8.1:
RSASSA-PSS, RFC 6234 [RFC6234], Section 7.1: SHA-Based HMACs, ANSI
X9.62-2005 ECDSA, P-256, and RFC 8032 [RFC8032], Section 5.1:
Ed25519ph, Ed25519ctx, and Ed25519.
Algorithm Name: rsa-sha1
Status: deprecated, SHA-1 not secure.
Canonicalization Algorithm: [RFC_THIS_DOCUMENT], Section 2.3:
Signature String Construction [23]
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Hash Algorithm: RFC 6234 [RFC6234], SHA-1 (SHA-1 with 160-bits of
digest output)
Digital Signature Algorithm: RFC 8017 [RFC8017], Section 8.2: RSASSA-
PKCS1-v1_5
Algorithm Name: rsa-sha256
Status: deprecated, specifying signature algorithm enables attack
vector.
Canonicalization Algorithm: [RFC_THIS_DOCUMENT], Section 2.3:
Signature String Construction [24]
Hash Algorithm: RFC 6234 [RFC6234], SHA-256 (SHA-2 with 256-bits of
digest output)
Digital Signature Algorithm: RFC 8017 [RFC8017], Section 8.2: RSASSA-
PKCS1-v1_5
Algorithm Name: hmac-sha256
Status: deprecated, specifying signature algorithm enables attack
vector.
Canonicalization Algorithm: [RFC_THIS_DOCUMENT], Section 2.3:
Signature String Construction [25]
Hash Algorithm: RFC 6234 [RFC6234], SHA-256 (SHA-2 with 256-bits of
digest output)
Message Authentication Code Algorithm: RFC 6234 [RFC6234],
Section 7.1: SHA-Based HMACs
Algorithm Name: ecdsa-sha256
Status: deprecated, specifying signature algorithm enables attack
vector.
Canonicalization Algorithm: [RFC_THIS_DOCUMENT], Section 2.3:
Signature String Construction [26]
Hash Algorithm: RFC 6234 [RFC6234], SHA-256 (SHA-2 with 256-bits of
digest output)
Digital Signature Algorithm: ANSI X9.62-2005 ECDSA, P-256
Authors' Addresses
Mark Cavage
Oracle
500 Oracle Parkway
Redwood Shores, CA 94065
US
Phone: +1 415 400 0626
Email: mcavage@gmail.com
URI: https://www.oracle.com/
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Manu Sporny
Digital Bazaar
203 Roanoke Street W.
Blacksburg, VA 24060
US
Phone: +1 540 961 4469
Email: msporny@digitalbazaar.com
URI: https://manu.sporny.org/
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