Curve25519: reduce to less than mod at end of curve25519, optimize to not use imulq when andq can be used instead. x86_64 Karatsuba Mul: Don't put add carry into overflow and then continue adding zero. Overflow is lost.
Curve25519: reduce to less than mod at end of curve25519, optimize to not use imulq when andq can be used instead. x86_64 Karatsuba Mul: Don't put add carry into overflow and then continue adding zero. Overflow is lost.