Re: [PATCH v2] lib/crypto: Add SHA3-224, SHA3-256, SHA3-384, SHA-512, SHAKE128, SHAKE256

[David Howells <dhowells@redhat.com>]

Eric Biggers <ebiggers@kernel.org> wrote:

> Also, the parameter should be strongly typed: 'struct sha3_state *'
> Likewise in all the other functions that take the raw u64 array.

Those function may be directly substituted by calls to assembly code - so
u64[] is probably more appropriate.

> > +	for (round = 0; round < KECCAK_ROUNDS; round++) {
> > +		keccakf_round(st);
> > +		/* Iota */
> > +		st[0] ^= keccakf_rndc[round];
> > +	}
> 
> In the spec, "Iota" is part of the round.  Having it be separate from
> keccakf_round() in the code is confusing.

I assume that pertains to the comment about inlining in some way.  This is as
is in sha3_generic.c.  I can move it into the round function if you like, but
can you tell me what the effect will be?

> Second, the support for update() + squeeze() + update() + squeeze()
> seems to be trying to achieve something that is not defined in the SHA-3
> spec.  Could you elaborate on what it is meant to be doing, and why it's
> here?  According to the spec, the XOFs SHAKE128 and SHAKE256 actually
> just take a single message as their input.

Turns out I was misunderstanding what I was looking at whilst trying to adapt
Leancrypto's dilithium code.  Whilst it does squeeze a context several times,
it doesn't update it after finalising it without reinitialising it.

David