this^(p-2) mod p, the field inverse.
Zero maps to zero. The exponent is the public constant p - 2 = 2^255 - 21, scanned from its most significant bit; branching on its bits does not depend on secrets.
this^(p-2) mod p, the field inverse.
Zero maps to zero. The exponent is the public constant p - 2 = 2^255 - 21, scanned from its most significant bit; branching on its bits does not depend on secrets.