tree c091f90594f4a6a670f972fa10004e0eaaf6dae6
parent 67546802fe4106f91bb12a2f8882ee191716f63c
author Gilles Peskine <Gilles.Peskine@arm.com> 1614199941 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> 1617022544 +0200

Define algorithms for EdDSA

Define algorithms for PureEdDSA and for HashEdDSA, the EdDSA variants
defined by RFC 8032.

The encoding for HashEdDSA needs to encode the hash algorithm so that
the hash can be calculated by passing PSA_ALG_SIGN_GET_HASH(sig_alg)
to psa_hash_compute() or psa_hash_setup(). As a consequence,
Ed25519ph (using SHA-512) and Ed448ph (using SHAKE256) need to have
different algorithm encodings (the key is enough to tell them apart,
but it is not known while hashing). Another consequence is that the
API needs to recognize the Ed448 prehash (64 bytes of SHAKE256 output)
as a hash algorithm.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>