[prev in list] [next in list] [prev in thread] [next in thread] 

List:       nettle-bugs
Subject:    Question on s390x AES acceleration
From:       Niels_Möller <nisse () lysator ! liu ! se>
Date:       2024-01-27 20:08:14
Message-ID: cpf7cju8rpt.fsf () shipon ! lysator ! liu ! se
[Download RAW message or body]

When I look at the logic in
https://git.lysator.liu.se/nettle/nettle/-/blob/master/fat-s390x.c?ref_type=heads,
automatic detection of hardware acceleration for aes128, aes192 and
aes256 is done independently for each key size, based on corresponding
bits in the "km status" words.

While when configured manually, at configure time or using
NETTLE_FAT_OVERRIDE, there are instead two flags, "msa_x1" enabling
aes128 (and sha256), and "msa_x2" enabling aes192, aes256 (and sha512).

I'm thinking that if we could enable all or none of the s390x aes
assembly, then we could make things a bit simpler, only overriding the
internal _nettle_aes_set_key and _nettle_aes_invert_key, instead of all
9 of aes{128,192,256}_{set_encrypt,set_decrypt,invert}_key.

Are there s390x machines out there that have hardware support for just
some of the aes key sizes but not all?

Regards,
/Niels
-- 
Niels Möller. PGP key CB4962D070D77D7FCB8BA36271D8F1FF368C6677.
Internet email is subject to wholesale government surveillance.

_______________________________________________
nettle-bugs mailing list -- nettle-bugs@lists.lysator.liu.se
To unsubscribe send an email to nettle-bugs-leave@lists.lysator.liu.se

[prev in list] [next in list] [prev in thread] [next in thread]