JWS Clear Text JSON Signature Option (JWS/CT)
draft-jordan-jws-ct-05
|
| Document |
Type |
|
Active Internet-Draft (individual)
|
|
Authors |
|
Bret Jordan
,
Samuel Erdtman
,
Anders Rundgren
|
|
Last updated |
|
2021-10-12
|
|
Stream |
|
Independent Submission
|
|
Intended RFC status |
|
Informational
|
|
Formats |
|
pdf
htmlized
bibtex
|
| Stream |
ISE state
|
|
In ISE Review
|
|
Consensus Boilerplate |
|
Unknown
|
|
Document shepherd |
|
Adrian Farrel
|
| IESG |
IESG state |
|
I-D Exists
|
|
Telechat date |
|
|
|
Responsible AD |
|
(None)
|
|
Send notices to |
|
rfc-ise@rfc-editor.org
|
Network Working Group B. Jordan, Ed.
Internet-Draft Broadcom
Intended status: Informational S. Erdtman
Expires: 15 April 2022 Spotify AB
A. Rundgren
Independent
12 October 2021
JWS Clear Text JSON Signature Option (JWS/CT)
draft-jordan-jws-ct-05
Abstract
This document describes a method for extending the scope of the JSON
Web Signature (JWS) standard, called JWS/CT. By combining the
detached mode of JWS with the JSON Canonicalization Scheme (JCS),
JWS/CT enables JSON objects to remain in the JSON format after being
signed (also known as "Clear Text" signing). In addition to
supporting a consistent data format, this arrangement also simplifies
documentation, debugging, and logging. The ability to embed signed
JSON objects in other JSON objects, makes the use of counter-
signatures straightforward.
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 15 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
Jordan, et al. Expires 15 April 2022 [Page 1]
Internet-Draft JWS/CT October 2021
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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Detailed Operation . . . . . . . . . . . . . . . . . . . . . 3
3.1. Signature Creation . . . . . . . . . . . . . . . . . . . 4
3.1.1. Create the JSON Object to be Signed . . . . . . . . . 4
3.1.2. Canonicalize the JSON Object to be Signed . . . . . . 4
3.1.3. Generate a JWS String . . . . . . . . . . . . . . . . 5
3.1.4. Assemble the Signed JSON Object . . . . . . . . . . . 5
3.2. Signature Validation . . . . . . . . . . . . . . . . . . 6
3.2.1. Parse the Signed JSON Object . . . . . . . . . . . . 6
3.2.2. Fetch the Signature Property String . . . . . . . . . 6
3.2.3. Remove the Signature Property String . . . . . . . . 6
3.2.4. Canonicalize the Remaining JSON Object . . . . . . . 7
3.2.5. Validate the JWS String . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Normative References . . . . . . . . . . . . . . . . . . 8
6.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Open-Source Implementations . . . . . . . . . . . . 10
Appendix B. JWS/CT Application Notes . . . . . . . . . . . . . . 10
B.1. Counter Signatures . . . . . . . . . . . . . . . . . . . 10
B.2. Detached Signatures . . . . . . . . . . . . . . . . . . . 11
B.3. Array of Signatures . . . . . . . . . . . . . . . . . . . 13
Appendix C. Test Vector Using the ES256 Algorithm . . . . . . . 14
Appendix D. Enhanced JWS Processing Option . . . . . . . . . . . 15
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 15
Document History . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
This specification introduces a method for augmenting data expressed
in the JSON [RFC8259] notation, with enveloped signatures, similar to
the scheme used in the XML Signature [XMLDSIG] standard. For
interoperability reasons this specification constrains JSON objects
to the I-JSON [RFC7493] subset.
To avoid "reinventing the wheel", this specification leverages the
JSON Web Signature (JWS) [RFC7515] standard.
Jordan, et al. Expires 15 April 2022 [Page 2]
Internet-Draft JWS/CT October 2021
By building on the detached mode of JWS in combination with the JSON
Canonicalizion Scheme (JCS) [RFC8785], JSON objects to be signed can
be kept in the JSON format. This arrangement is here referred to as
JWS/CT, where CT stands for "Clear Text" signing.
The primary motivations for keeping signed JSON objects in the JSON
format include simplified documentation, debugging, and logging, as
well as for maintaining a consistent message structure.
Another target is HTTP-based signature schemes that currently utilize
HTTP header values for holding detached signatures. By rather using
the method described herein, signed JSON-formatted HTTP requests and
responses may be self-contained and thus be serializable. The latter
facilitates such data to be
* stored in databases
* passed through intermediaries
* embedded in other JSON objects
* counter-signed
without losing the ability to (at any time) verify signatures.
Appendix B outlines different ways to handle multiple signatures
including counter-signing using JWS/CT.
The intended audiences of this document are JSON tool vendors as well
as designers of JSON-based cryptographic solutions.
2. Terminology
Note that this document is not on the IETF standards track. However,
a conformant implementation is supposed to adhere to the specified
behavior for security and interoperability reasons. This text uses
BCP 14 to describe that necessary behavior.
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.
3. Detailed Operation
This section describes the details related to signing and validating
signatures based on this specification.
The following characteristics are vital to know for prospective JWS/
CT implementers and users:
Jordan, et al. Expires 15 April 2022 [Page 3]
Internet-Draft JWS/CT October 2021
* With the exception of the reliance on the detached mode described
in Appendix F of JWS [RFC7515], JWS/CT does not alter the JWS
signature creation process, validation process, or format. This
means that the contents of JWS headers as well as things related
to signature algorithms and cryptographic keys are out of scope
for this specification. A slightly enhanced processing option is
outlined in Appendix D.
* JWS/CT exclusively depends on the JWS Compact Serialization mode.
* JCS [RFC8785] constrains JSON objects to the I-JSON [RFC7493]
subset.
The signature creation and signature validation sections feature
examples using the HS256 JOSE algorithm [RFC7518] with a 256-bit key
having the following value, here expressed as hexadecimal bytes:
7f dd 85 1a 3b 9d 2d af c5 f0 d0 00 30 e2 2b 93
43 90 0c d4 2e de 49 48 56 8a 4a 2e e6 55 29 1a
3.1. Signature Creation
The following sub-sections describe how JSON objects can be signed
according to the JWS/CT specification.
3.1.1. Create the JSON Object to be Signed
Create or parse the JSON object to be signed.
For illustrating the subsequent operations the following example
object is used:
{
"statement": "Hello signed world!",
"otherProperties": [2000, true]
}
3.1.2. Canonicalize the JSON Object to be Signed
Use the result of the previous step as input to the canonicalization
process described in JCS [RFC8785].
Applied to the example, the following JSON string should be
generated:
{"otherProperties":[2000,true],"statement":"Hello signed world!"}
Jordan, et al. Expires 15 April 2022 [Page 4]
Internet-Draft JWS/CT October 2021
After encoding the string above in the UTF-8 [UNICODE] format, the
following bytes (here in hexadecimal notation) should be generated:
7b 22 6f 74 68 65 72 50 72 6f 70 65 72 74 69 65 73 22 3a 5b 32 30
30 30 2c 74 72 75 65 5d 2c 22 73 74 61 74 65 6d 65 6e 74 22 3a 22
48 65 6c 6c 6f 20 73 69 67 6e 65 64 20 77 6f 72 6c 64 21 22 7d
3.1.3. Generate a JWS String
Use the result of the previous step as JWS Payload to the signature
process described in Appendix F of JWS [RFC7515].
For the example, the JWS header is assumed to be:
{"alg":"HS256"}
The resulting JWS string should then after payload removal and using
the key specified in Section 3, read as follows:
eyJhbGciOiJIUzI1NiJ9..VHVItCBCb8Q5CI-49imarDtJeSxH2uLU0DhqQP5Zjw4
3.1.4. Assemble the Signed JSON Object
Before a complete signed object can be created, a dedicated top-level
property for holding the JWS signature string needs to be defined.
The only requirement is that this property MUST NOT clash with any
other top-level property name. The JWS string itself MUST be
supplied as a JSON string argument to the signature property.
For the example, the property name "signature" is assumed to be the
designated holder of the JWS string. Equipped with a signature
property, the JWS string from the previous section, and the original
JSON example, the process above should result in the following, now
signed JSON object (with a line break in the "signature" property for
display purposes only):
{
"statement": "Hello signed world!",
"otherProperties": [2000, true],
"signature": "eyJhbGciOiJIUzI1NiJ9..VHVItCBCb8Q5CI-49imar
DtJeSxH2uLU0DhqQP5Zjw4"
}
Note: one could equally well apply the signature to the canonicalized
version of the JSON object. However, the rearrangement of properties
(performed by JCS), may sometimes be considered an issue from a
"human" point of view, while computing-wise the order of JSON
properties has no impact on the outcome.
Jordan, et al. Expires 15 April 2022 [Page 5]
Internet-Draft JWS/CT October 2021
3.2. Signature Validation
The following sub-sections describe how JSON objects signed according
to the JWS/CT specification can be validated.
3.2.1. Parse the Signed JSON Object
Parse the JSON object that is anticipated to be signed. If the
parsing is unsuccessful, the operation MUST cause a compliant
implementation to terminate with an appropriate error.
To illustrate the subsequent operations the signed JSON object
featured in Section 3.1.4 is used as example.
3.2.2. Fetch the Signature Property String
After successful parsing, retrieve the designated JSON top-level
property holding the JWS string. If the property is missing or its
argument is not a JSON string value, the operation MUST cause a
compliant implementation to terminate with an appropriate error.
For the example, where the property named "signature" is assumed to
hold the JWS string, the operation above should return the following
string:
eyJhbGciOiJIUzI1NiJ9..VHVItCBCb8Q5CI-49imarDtJeSxH2uLU0DhqQP5Zjw4
3.2.3. Remove the Signature Property String
Since the signature is calculated over the actual JSON object data,
the designated signature property and its argument MUST be removed
from the signed JSON object.
If applied to the example the resulting JSON object should read as
follows:
{
"statement": "Hello signed world!",
"otherProperties": [2000, true]
}
Note: JSON tools usually by default remove whitespace. In addition,
the original ordering of properties may not always be honored.
However, none of this has (due to the canonicalization performed by
JCS), any impact on the result.
Jordan, et al. Expires 15 April 2022 [Page 6]
Internet-Draft JWS/CT October 2021
3.2.4. Canonicalize the Remaining JSON Object
Use the result of the previous step as input to the canonicalization
process described in JCS [RFC8785].
If applied to the example the result of the process above should read
as follows:
{"otherProperties":[2000,true],"statement":"Hello signed world!"}
After encoding the string above in the UTF-8 [UNICODE] format, the
following bytes (here in hexadecimal notation) should be generated:
7b 22 6f 74 68 65 72 50 72 6f 70 65 72 74 69 65 73 22 3a 5b 32 30
30 30 2c 74 72 75 65 5d 2c 22 73 74 61 74 65 6d 65 6e 74 22 3a 22
48 65 6c 6c 6f 20 73 69 67 6e 65 64 20 77 6f 72 6c 64 21 22 7d
3.2.5. Validate the JWS String
After extracting the detached mode JWS string and canonicalizing the
JSON object (to retrieve the JWS Payload), the JWS string MUST be
restored as described in https://tools.ietf.org/html/
rfc7515#appendix-F of JWS [RFC7515]. The actual JWS validation
procedure is not specified here because it is covered by [RFC7515]
and also depends on application-specific policies like:
* Accepted JWS signature algorithms
* Accepted and/or required JWS header elements
* Signature key lookup methods
If the validation process for some reason fails, the operation MUST
cause a compliant implementation to terminate with an appropriate
error.
For the example, validation is straightforward since both the
algorithm and the key to use are predefined (see Section 3). The
input string to a JWS validator should after the process step above
read as follows (with line breaks for display purposes only):
eyJhbGciOiJIUzI1NiJ9.eyJvdGhlclByb3BlcnRpZXMiOlsyMDAwLHRydWVdLCJzdGF0
ZW1lbnQiOiJIZWxsbyBzaWduZWQgd29ybGQhIn0.VHVItCBCb8Q5CI-49imarDtJeSxH2
uLU0DhqQP5Zjw4
4. IANA Considerations
This document has no IANA actions.
Jordan, et al. Expires 15 April 2022 [Page 7]
Internet-Draft JWS/CT October 2021
5. Security Considerations
This specification inherits all the security considerations of JWS
[RFC7515] and JCS [RFC8785].
In similarity to any other signature specification, it is crucial
that signatures are verified before acting on the signed payload.
However, poorly tested software components may also introduce
security issues. Consider the following JSON example:
{
"fromAccount": "1234",
"toAccount": "4567",
"amount": {
"value": 100,
"currency":"USD"
}
}
A non-compliant JCS implementation could return
{"amount":{},"fromAccount":"1234","toAccount":"4567"}
giving an attacker the ability to change "amount" to whatever it
wants. Note though that this attack presumes that the consumer and
producer use implementations broken in the same way, otherwise the
signature would not validate.
For usage in a wider community, the name of the designated signature
property becomes a critical factor that MUST be documented and
communicated. However, in a properly designed system, a faulty or
missing signature MUST "only" lead to failed operation, and not to a
security breach.
6. References
6.1. Normative References
[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>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<https://www.rfc-editor.org/info/rfc7493>.
Jordan, et al. Expires 15 April 2022 [Page 8]
Internet-Draft JWS/CT October 2021
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
[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>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8785] Rundgren, A., Jordan, B., and S. Erdtman, "JSON
Canonicalization Scheme (JCS)", RFC 8785,
DOI 10.17487/RFC8785, June 2020,
<https://www.rfc-editor.org/info/rfc8785>.
[UNICODE] The Unicode Consortium, "The Unicode Standard",
<https://www.unicode.org/versions/latest/>.
6.2. Informative 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>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/info/rfc7517>.
[RFC7797] Jones, M., "JSON Web Signature (JWS) Unencoded Payload
Option", RFC 7797, DOI 10.17487/RFC7797, February 2016,
<https://www.rfc-editor.org/info/rfc7797>.
[SHS] NIST, "Secure Hash Standard (SHS)", FIPS PUB 180-4, August
2015, <https://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.180-4.pdf>.
[XMLDSIG] W3C, "XML Signature Syntax and Processing Version 1.1",
W3C Recommendation, April 2013,
<https://www.w3.org/TR/xmldsig-core1/>.
Jordan, et al. Expires 15 April 2022 [Page 9]
Internet-Draft JWS/CT October 2021
Appendix A. Open-Source Implementations
Due to the simplicity of this specification, there is hardly a need
for specific support software. However, JCS which is (at the time of
writing), a relatively new design, may be fetched as a separate
component for multiple platforms. The following open-source
implementations have been verified to be compatible with JCS:
* JavaScript: <https://www.npmjs.com/package/canonicalize>
* Java: <https://mvnrepository.com/artifact/io.github.erdtman/java-
json-canonicalization>
* Go: <https://github.com/cyberphone/json-
canonicalization/tree/master/go>
* .NET/C#: <https://github.com/cyberphone/json-
canonicalization/tree/master/dotnet>
* Python: <https://github.com/cyberphone/json-
canonicalization/tree/master/python3>
Appendix B. JWS/CT Application Notes
The following application notes are not a part of the JWS/CT core;
they show how JWS/CT can be used in contexts involving multiple
signatures.
B.1. Counter Signatures
Consider the following JWS/CT object showing an imaginary real estate
business record (with a line break in the "signature" property for
display purposes only):
{
"gps": [38.89768255588178, -77.03658644893932],
"object": {
"type": "house",
"price": "$635,000"
},
"role": "buyer",
"name": "John Smith",
"timeStamp": "2020-11-08T13:56:08Z",
"signature": "eyJhbGciOiJIUzI1NiJ9..zlPMniQiz4Eie86oK4xo25z
uyW92csiDqyiQrF6R5ug"
}
The signature above was created using the example key from Section 3.
Jordan, et al. Expires 15 April 2022 [Page 10]
Internet-Draft JWS/CT October 2021
Adding a notary signature on top of this could be performed by
embedding the former object as follows (with line breaks in the
"signature" properties for display purposes only):
{
"attesting": {
"gps": [38.89768255588178, -77.03658644893932],
"object": {
"type": "house",
"price": "$635,000"
},
"role": "buyer",
"name": "John Smith",
"timeStamp": "2020-11-08T13:56:08Z",
"signature": "eyJhbGciOiJIUzI1NiJ9..zlPMniQiz4Eie86oK4xo25z
uyW92csiDqyiQrF6R5ug"
},
"role": "notary",
"name": "Carol Lombardi-Jones",
"timeStamp": "2020-11-08T13:58:42Z",
"signature": "eyJhbGciOiJFUzI1NiJ9..AVmJGUWp1JD0pf2j1_UQWXbf-
qj-2RWxOnyAXihd4POKbnjWqqSBmHPNfgMQFH_s5sXHkIOkDZe2nShqEJOEVA"
}
A side effect of this arrangement is that the notary's signature
signs not only the notary data, but the buyer's data and signature as
well. In most cases this way of adding signatures is advantageous
since it maintains the actual order of signing events which also
cannot be tampered with without invalidating the outermost signature.
Note that all properties above including "signature" are application
specific.
The notary's signature was created using the example key from
Appendix C.
B.2. Detached Signatures
In the case the signing entities are "peers" or are unrelated to each
other, counter-signatures like described in Appendix B.1 are not
applicable since they presume a specific flow. For supporting
independent or asynchronous signers targeting a common document or
data object, an imaginable solution is using a scheme where each
signer calculates a hash of the target document/data and includes the
hash together with signer-specific meta data like the following:
Jordan, et al. Expires 15 April 2022 [Page 11]
Internet-Draft JWS/CT October 2021
{
<<Common Document/Data to Sign...>>
"signers": [{
"sha256": "<<Hash of Document/Data to Sign>>",
<<Signer-related meta data...>>
"signature": "<<Signer JWS Signature>>"
},{
"sha256": "<<Hash of Document/Data to Sign>>",
<<Signer-related meta data...>>
"signature": "<<Signer JWS Signature>>"
}]
}
In this case the object to sign would not be limited to JSON; it
could for example be a PDF document hosted on a specific URL. Note
that the relying party would have to update the structure for each
signature received. In some cases a database would probably be more
useful for holding individual signatures since a database can cope
with any number of signers as well as keeping track of who have
actually signed. The latter is crucial for things like international
treaties and company board statements.
Note that although "signers", "sha256", and "signature" are
application specific property names, the objects in the "signers"
array are assumed to be fully conformant with the JWS/CT
specification.
The following example shows a possible detached signature solution
(with line breaks in the "signature" properties for display purposes
only):
Jordan, et al. Expires 15 April 2022 [Page 12]
Internet-Draft JWS/CT October 2021
{
"statement": "Hello signed world!",
"otherProperties": [2000, true],
"signers": [{
"sha256": "n-i0HIBJKELoTicCK9c5nqJ8cYH0znGRcEbYKoQfm70",
"timeStamp": "2020-11-18T07:45:28Z",
"name": "Alice",
"signature": "eyJhbGciOiJIUzI1NiJ9..AE7CnzSYsaspE3yrdsAwi
avd3IdWtdAmDE8FRMwYLA8"
},{
"sha256": "n-i0HIBJKELoTicCK9c5nqJ8cYH0znGRcEbYKoQfm70",
"timeStamp": "2020-11-18T08:03:40Z",
"name": "Bob",
"signature": "eyJhbGciOiJFUzI1NiJ9..0tNLy0pLcHUjPhhorpKd5
7a8zTPeqlrOjATiSlPQ1vciE99x6mHmow04tPbJS8dqSqO9c4RkKW6jeL4ZyWpXLA"
}]
}
Notes:
* "Alice" used the example key from Section 3 while "Bob" used the
example key specified in Appendix C.
* The "sha256" properties hold base64url-encoded [RFC4648],
SHA256-hashes [SHS] of the canonicalized data created in
Section 3.1.2.
* This arrangement requires a two-step validation process where each
JWS/CT object in the "signers" array is individually validated, as
well as having its "sha256" property compared with the actual hash
of the canonicalized common data.
B.3. Array of Signatures
Another possibility supporting multiple and independent signatures is
collecting JWS signature strings in a JSON array object according to
the following scheme:
{
<<Common Document/Data to Sign...>>
"<<Signature property>>": ["<<Signature-1>>",
"<<Signature-2>>",
.
"<<Signature-n>>"]
}
Jordan, et al. Expires 15 April 2022 [Page 13]
Internet-Draft JWS/CT October 2021
Processing would follow Section 3, with the addition that each
signature is dealt with individually.
Compared to Appendix B.2, signature arrays imply that possible
signer-specific meta-data is supplied as JWS extensions in the
associated signature's base64url-encoded header.
By combining the example used in Section 3 with the test vector in
Appendix C, a valid signature array object could be as follows (with
line breaks in the "signatures" property for display purposes only):
{
"statement": "Hello signed world!",
"otherProperties": [2000, true],
"signatures": ["eyJhbGciOiJIUzI1NiJ9..VHVItCBCb8Q5CI-49imar
DtJeSxH2uLU0DhqQP5Zjw4",
"eyJhbGciOiJFUzI1NiJ9..ENP0j0-QPsA7N_Mg1-RMN
9IxapeTWtQwR7sPUqEiSNHPuV_fqSdRqqkLOlBdV01cc4lSJdn1XCv-ZHYdZ9t3kA"]
}
Note that "signatures" is not a keyword, it was only selected to
highlight the fact that there are multiple signatures.
Appendix C. Test Vector Using the ES256 Algorithm
This appendix shows how a signed version of the JSON example object
in Section 3.1.1 would look like if applying the ES256 JOSE algorithm
[RFC7518] (with a line break in the "signature" property for display
purposes only):
{
"statement": "Hello signed world!",
"otherProperties": [2000, true],
"signature": "eyJhbGciOiJFUzI1NiJ9..ENP0j0-QPsA7N_Mg1-RMN
9IxapeTWtQwR7sPUqEiSNHPuV_fqSdRqqkLOlBdV01cc4lSJdn1XCv-ZHYdZ9t3kA"
}
The example above depends on a JWS header holding the algorithm
{"alg":"ES256"}, and the following private key, here expressed in the
JWK [RFC7517] format:
{
"kty": "EC",
"crv": "P-256",
"x": "6BKxpty8cI-exDzCkh-goU6dXq3MbcY0cd1LaAxiNrU",
"y": "mCbcvUzm44j3Lt2b5BPyQloQ91tf2D2V-gzeUxWaUdg",
"d": "6XxMFXhcYT5QN9w5TIg2aSKsbcj-pj4BnZkK7ZOt4B8"
}
Jordan, et al. Expires 15 April 2022 [Page 14]
Internet-Draft JWS/CT October 2021
Note that signing with the ES256 algorithm returns different results
for each signature due to a randomization step in the signature
computation process.
Appendix D. Enhanced JWS Processing Option
By default, JWS/CT uses the JWS compact serialization mode "as is".
As a consequence, a technically redundant, internal-only, base64url
encoding step is performed over the JWS Payload. Although the
performance hit should be marginal for most real-world applications,
a possibility is using the "Unencoded Payload" mode of RFC7797
[RFC7797]. However, this requires that the JWS implementation
supports the "b64":false and "crit":["b64"] header elements implied
by RFC7797, effectively rendering the RFC7797 mode as an implementer
option for specific communities.
Acknowledgements
People who have contributed directly and indirectly with valuable
input to this specification include Vladimir Dzhuvinov, Freddi Gyara,
and Filip Skokan.
Document History
[[ This section to be removed by the RFC Editor before publication as
an RFC ]]
Version 00:
* Initial publication.
Version 01:
* Added paragraph to Abstract.
* Updated Security Considerations.
Version 02:
* Changed alternative test key to ES256/P-256.
* Moved RFC7797 to an appendix.
* Changed <tt> to only be used on keywords.
* Added some clarity to detached signatures.
Version 03:
Jordan, et al. Expires 15 April 2022 [Page 15]
Internet-Draft JWS/CT October 2021
* Language changes suggested by ISE.
Version 04:
* Language nit.
Version 05:
* Document refresh.
Authors' Addresses
Bret Jordan (editor)
Broadcom
1320 Ridder Park Drive
San Jose, CA 95131
United States of America
Email: bret.jordan@broadcom.com
Samuel Erdtman
Spotify AB
Birger Jarlsgatan 61, 4tr
SE-113 56 Stockholm
Sweden
Email: erdtman@spotify.com
Anders Rundgren
Independent
Montpellier
France
Email: anders.rundgren.net@gmail.com
URI: https://www.linkedin.com/in/andersrundgren/
Jordan, et al. Expires 15 April 2022 [Page 16]