[curves] curve25519-donna stack usage

Jason A. Donenfeld Jason at zx2c4.com
Wed Nov 9 10:00:20 PST 2016

Hey guys,

I use a curve25519-donna variant inside of WireGuard [1]. It runs in a
kthread in kernel space, which only has 8k of stack in total. Some
circuitous paths in the kernel into code actually amount to having
much less stack available. I could allocate curve25519 variables on
the heap instead, or try to do various other traditional programming
techniques to reduce usage. But before I put too much time into that,
I was wondering if anybody else has ran into this limitation with
-donna and if there are other common portable implementations of
curve25519 that use less stack while remaining performant, or if there
are various other tricks to reduce stack usage.


[1] https://www.wireguard.io/

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