No-float policy for secp256k1

[laanwj]

I think secp256k1 needs an explicit no-floating point policy, like the Linux kernel. This means no use of float, and no double (and no half, no long double either).

• It has to be able to run in kernel context
• Boot and security processors tend to have no FP support (e.g. core 0 on the Sifive U54)
• FP hardware implementation is possibly inconsistent between platforms which is useless for cryptography

I mean for the main code; in the bench framework is fine, though with the assumption that it might be emulated and very slow.

(inspired by #658 (comment))

[elichai]

For the record it was a hypothetical. I wasn't serious in using floats... (which we obviously should almost never use ever)

[real-or-random]

No worries :)

[laanwj]

For the record it was a hypothetical. I wasn't serious in using floats... (which we obviously should almost never use ever)

I know it was more or less a joke in your case!

But it's just good to have these things explicit, so developers as well as users of the library have some certainly.