Re: [PATCH v5 04/19] crypto: cmh - add SHA-2/SHA-3/SHAKE ahash

[Herbert Xu <herbert@gondor.apana.org.au>]

On Mon, Oct 05, 2026 at 05:04:25PM +0000, Ousherovitch, Alex wrote:
>
> > Please also elaborate what you mean by opaque checkpoint, does it
> > contain the entire hash state or not?
> 
> It holds everything needed to resume, but not in a portable layout.  The
> SAVE output is a fixed-size hardware container (600 bytes worst case)
> holding the core's internal state, the buffered partial block, the block
> counters, the mode and a CRC.  The state portion varies by algorithm:
> 
>   - SHA-3/SHAKE: the 200-byte Keccak state is stored as two shares (the
>     core is DPA/side-channel protected), so it is not the canonical
>     state.
>   - SHA-2: a single 64-byte register block plus the partial block and
>     byte count, in a hardware-internal layout.
>   - Keyed SHA-3 HMAC state cannot be saved by the hardware at all.

So it sounds like the info is there.  Is it possible to transform
this to the format that we use?

> None of these is the canonical export format the API needs, so the
> fallback/digest-only model above is the right fit and we are not pursuing
> incremental hashing upstream.

That's we have the export and import functions, to transcribe
the hardware hash state into a standard format.

> One process question, if you don't mind: we would like to fold as much as
> possible into v6 rather than spinning several revisions.  Have you had a
> chance to look at the rest of the series, or should we expect further
> comments on the remaining patches?  No rush at all -- it would just help
> us decide whether to post v6 now or hold it until the rest of your
> feedback has landed.

I would appreciate it if you can break the series into smaller
chunks.  Perhaps add the algorithms which are the least problematic
first.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt