Nettle: Enable AES-NI instructions on amd64.

[David Korth]

The current build of libnettle6 does not have AES-NI enabled. There's two configure options for enabling it:

--enable-x86-aesni: Use AES-NI instructions instead of the standard implementation. This will break on systems that don't have AES-NI.
--enable-fat: Build a "fat" library that has the standard implementation and the AES-NI implementation. This allows the library to continue working on older systems while providing faster performance on systems that have AES-NI.

Note that Nettle's AES-NI implementation as of v3.2 is only supported on amd64, not i386, so this would only affect the 64-bit package.

[Vladimír Čunát (vcunat)]

There's also SHA* acceleration in --enable-fat and some 32-bit ARM assembler IIRC. In pure crypto the speedup can be quite significant (like 5x in one of my tests).

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Richard Henderson (rth)]

Note that the upstream debian 3.6 package uses --enable-fat,
but that also builds libnettle.so.8.

It would be nice to have this configure option added to the
3.5.1 package which builds libnettle.so.7.

[Christian Ehrhardt  (paelzer)]

Indeed (thanks Richard) that is enabled since 3.6-1.

It is unlikely though due to the associated symbol changes (see e.g. the old changelogs) that this can be provided as an SRU for older releases. I'm not saying impossible, just unlikely as that evaluation has to be done and checked in depth for potential side-effects in regard to an SRU.