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Re: [openpgp] SHA3 algorithm ids.

2015-08-08 07:43:35
What is the rationale to implement all sha3 variants?

I understand some protocols need lower grade versions for performance reasons 
but that seems to matter a lot less for openpgp usage. Why not just implement 
sha3-512?

Sent from my iPhone

On Aug 8, 2015, at 11:21, Werner Koch <wk(_at_)gnupg(_dot_)org> wrote:

Hi!

Now that an official SHA3 specs has been published I would like to see
algorithm ids assigned.  Although it is some time until we can publish
rfc-4880bis, it would be useful to agree on the algorithm ids now.
This would be helpful for experimental implementations.  Thus what about
this new table with the SHA2 drop in replacements:

     ID           Algorithm                             Text Name
     --           ---------                             ---------
     1          - MD5 [HAC]                             "MD5"
     2          - SHA-1 [FIPS180]                       "SHA1"
     3          - RIPE-MD/160 [HAC]                     "RIPEMD160"
     4          - Reserved
     5          - Reserved
     6          - Reserved
     7          - Reserved
     8          - SHA256 [FIPS180]                      "SHA256"
     9          - SHA384 [FIPS180]                      "SHA384"
     10         - SHA512 [FIPS180]                      "SHA512"
     11         - SHA224 [FIPS180]                      "SHA224"
     12         - SHA3-224 [FIPS202]                    "SHA3-224"
     13         - SHA3-256 [FIPS202]                    "SHA3-256"
     14         - SHA3-384 [FIPS202]                    "SHA3-384"
     15         - SHA3-512 [FIPS202]                    "SHA3-512"
     100 to 110 - Private/Experimental algorithm

Note that I ordered SHA3-224 first; when we did SHA2 we forgot about 224
and thus it ended up out of order.

I am not sure about the text name.  Is a dash okay (cf. armor header)?

The OIDS are:

  The hexadecimal representations for the
  currently defined hash algorithms are as follows:

    [...]  

    - SHA3-224:   0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x07
    - SHA3-256:   0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x08
    - SHA3-384:   0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x09
    - SHA3-512:   0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x0a

  The ASN.1 Object Identifiers (OIDs) are as follows:

    [...]

    - SHA3-224:   2.16.840.1.101.3.4.2.7
    - SHA3-256:   2.16.840.1.101.3.4.2.8
    - SHA3-384:   2.16.840.1.101.3.4.2.9
    - SHA3-512:   2.16.840.1.101.3.4.2.10

  The full hash prefixes for these are as follows:

      [...]

      SHA3-224:   0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
                  0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x07, 0x05,
                  0x00, 0x04, 0x40

      SHA3-256:   0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
                  0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x07, 0x05,
                  0x00, 0x04, 0x40

      SHA3-384:   0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
                  0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x07, 0x05,
                  0x00, 0x04, 0x40

      SHA3-512:   0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
                  0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x07, 0x05,
                  0x00, 0x04, 0x40



Shalom-Salam,

  Werner


-- 
Die Gedanken sind frei.  Ausnahmen regelt ein Bundesgesetz.

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