operations modulo m. // // The announced size of x must be smaller than or equal to that of m. func (x *Nat) ExpandFor(m *Modulus) *Nat { return x.expand(len(m.nat.limbs)) } // resetFor ensures out has the right size to work with operations modulo m. // // out is zeroed and may start at any size. func (out *Nat) resetFor(m *Modulus) *Nat { return out.reset(len(m.nat.limbs)) } // maybeSubtractModulus computes x -= m if and only if x >= m or if "always" is yes. // // It can be used to reduce modulo...