Make mul_rem() primitive constant-time
#625
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fjarri
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tarcieri
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Aug 2, 2024
| /// Computes `(a * b) % d`. | ||
| #[inline(always)] | ||
| pub(crate) const fn mul_rem(a: Word, b: Word, d: Word) -> Word { | ||
| ((a as WideWord * b as WideWord) % (d as WideWord)) as Word |
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Perhaps we should enable the clippy::integer_division_remainder_used lint
tarcieri
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Aug 2, 2024
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As mentioned in #511,
mul_rem()is currently variable-time ind, which makesmul_mod_special()variable-time inc. This PR makesmul_rem()constant-time with no loss of performance.Since
mul_modnow uses thediv_limbfunctionality, it was moved there.Also added
NonZero::<Limb>::new_unwrap().