s.Bytes(c.N)}, nil } // inverse sets kInv to the inverse of k modulo the order of the curve. func inverse[P Point[P]](c *Curve[P], kInv, k *bigmod.Nat) { if c.ordInverse != nil { kBytes, err := c.ordInverse(k.Bytes(c.N)) // Some platforms don't implement ordInverse, and always return an error. if err == nil { _, err := kInv.SetBytes(kBytes, c.N) if err != nil { panic("ecdsa: internal error: ordInverse produced an invalid value") } return } } // Calculate the inverse of s in GF(N) using Fermat's method // (exponentiation...