Re: [openpgp] changing v5 signature salt size from 16 to 32 octets? [was: Re: lack of agenda items...]

[Steffen Nurpmeso <[e-mail]>]

Daniel Kahn Gillmor wrote in
 <[e-mail]>:
 |On Thu 2022-11-03 08:32:00 +0000, Aron Wussler wrote:
 ...
 |> (1) it is possible to extend the field to 32 bytes to match other \
 |> constructions,
 |
 |Are there any size concerns worth considering here?
 |
 |The salt needs to be represented in a few different contexts:
 |
 | - in the one-pass signature packet
 | - in the SaltedHash Armor header for a (LIT SIG)-style signed
 |   message (non-one-pass), and probably
 | - in some sort of RFC 3156-style parameter to enable one-pass
 |   validation of a signed e-mail message.
 |
 |base64-encoding the 32-byte value will bring this to 43 characters.
 |
 |That would make the SaltedHash: armor header 43+13+8 = 64 characters
 |long, like so:
 |
 |SaltedHash: SHA3-256:9haH8LirCmteTImei9GQtIHMgJ26zM/uPAoiZepB4cw

As an outsider, but now that i see this.  If this is subject to
design i personally would use "Base 64 Encoding with URL and
Filename Safe Alphabet" aka base64url as in RFC 4648, section 5.
Maybe that would be of value some day.

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)