PuTTY wish cpu-crypto-accel

This is a mirror. Follow this link to find the primary PuTTY web site.

summary: Use CPU cryptographic acceleration instructions where available
class: wish: This is a request for an enhancement.
difficulty: taxing: Needs external things we don't have (standards, users etc)
fixed-in: dc2fdb8acf19b5a51d4d9bb7d84ad7190b73205c 2019-01-24 (0.71)

Some modern CPUs have instructions specifically for accelerated implementation of certain crypto primitives.

PuTTY now makes use of these instructions, if available, both on Intel x86 and on Arm (including the new Windows on Arm builds, arm-windows-build).

AES
- On Intel x86: using the AES-NI instruction (widely available)
- On Arm: via NEON extensions
SHA-1 and SHA-256
- On Intel x86: using the SHA-NI instruction (still quite rare)
- On Arm: via NEON extensions

There's a blog post with some technical details about the Arm implementation: copies are on the Arm Community site and Simon's own website.

You can tell whether these instructions are being used from the Event Log. If they are not, the relevant message will mention "(unaccelerated)".

(This can't currently be disabled in PuTTY's configuration. We'd probably accept a good-quality patch to do so.)

If you want to comment on this web site, see the Feedback page.

Audit trail for this wish.

(last revision of this bug record was at 2023-01-25 10:42:49 +0000)