draft-ietf-cose-hash-algs-07.txt   draft-ietf-cose-hash-algs-08.txt 
Network Working Group J. Schaad Network Working Group J. Schaad
Internet-Draft August Cellars Internet-Draft August Cellars
Intended status: Informational 29 July 2020 Intended status: Informational 29 July 2020
Expires: 30 January 2021 Expires: 30 January 2021
CBOR Object Signing and Encryption (COSE): Hash Algorithms CBOR Object Signing and Encryption (COSE): Hash Algorithms
draft-ietf-cose-hash-algs-07 draft-ietf-cose-hash-algs-08
Abstract Abstract
The CBOR Object Signing and Encryption (COSE) syntax The CBOR Object Signing and Encryption (COSE) syntax
[I-D.ietf-cose-rfc8152bis-struct] does not define any direct methods [I-D.ietf-cose-rfc8152bis-struct] does not define any direct methods
for using hash algorithms. There are, however, circumstances where for using hash algorithms. There are, however, circumstances where
hash algorithms are used, such as indirect signatures where the hash hash algorithms are used, such as indirect signatures where the hash
of one or more contents are signed, and X.509 certificate or other of one or more contents are signed, and X.509 certificate or other
object identification by the use of a fingerprint. This document object identification by the use of a fingerprint. This document
defines a set of hash algorithms that are identified by COSE defines a set of hash algorithms that are identified by COSE
skipping to change at page 8, line 49 skipping to change at page 8, line 49
and SHAKE-256 are the instances of SHA-3 that are currently being and SHAKE-256 are the instances of SHA-3 that are currently being
standardized in the IETF. This is the reason for including these standardized in the IETF. This is the reason for including these
algorithms in this document. algorithms in this document.
The SHA-3 hash algorithms have a significantly different structure The SHA-3 hash algorithms have a significantly different structure
than the SHA-2 hash algorithms. One of the benefits of this than the SHA-2 hash algorithms. One of the benefits of this
difference is that when computing a shorter SHAKE hash value, the difference is that when computing a shorter SHAKE hash value, the
value is not a prefix of the result of computing the longer hash. value is not a prefix of the result of computing the longer hash.
Unlike the SHA-2 hash functions, no algorithm identifier is created Unlike the SHA-2 hash functions, no algorithm identifier is created
for shorter lengths. The length of the hash value stored is 128-bits for shorter lengths. The length of the hash value stored is 256-bits
for SHAKE-128 and 256-bits for SHAKE-256. for SHAKE-128 and 512-bits for SHAKE-256.
The COSE capabilities array for these algorithms is empty. The COSE capabilities array for these algorithms is empty.
+========+=====+=============+==============+=========+=============+ +========+=====+=============+==============+=========+=============+
| Name |Value| Description | Capabilities |Reference| Recommended | | Name |Value| Description | Capabilities |Reference| Recommended |
+========+=====+=============+==============+=========+=============+ +========+=====+=============+==============+=========+=============+
|SHAKE128|TBD10| SHAKE-128 | [] | [This | Yes | |SHAKE128|TBD10| SHAKE-128 | [] | [This | Yes |
| | |256-bit Hash | |Document]| | | | |256-bit Hash | |Document]| |
| | | Value | | | | | | | Value | | | |
+--------+-----+-------------+--------------+---------+-------------+ +--------+-----+-------------+--------------+---------+-------------+
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