Harden constant-time equality on arrays and slices#120
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The current implementation of
ConstantTimeEqualityfor arrays and slices will short-circuit if the lengths are different. This PR does a constant-time length check before the componentwise check, and then uses a constant-timeBitAndfor the final result.This still strikes me as controversial, since both the existing implementation and this update leak something about length:
This seems like at worst no improvement, and at best a reasonable improvement.