not the identity element, and returns the // x-coordinate of the result, performing Steps 2-5 of Section 5.7.1.2. return p.BytesX() } // isZero reports whether x is all zeroes in constant time. func isZero(x []byte) bool { var acc byte for _, b := range x { acc |= b } return acc == 0 } // isLess reports whether a < b, where a and b are big-endian buffers of the // same length and shorter than 72 bytes. func isLess(a, b []byte) bool { if len(a) != len(b) { panic("crypto/ecdh: internal error: mismatched...