gcmPlatformData struct { productTable [256]byte } func initGCM(g *GCM) { if !supportsAESGCM { return } gcmAesInit(&g.productTable, aes.EncryptionKeySchedul(&g.cipher)) } func seal(out []byte, g *GCM, nonce, plaintext, data []byte) { if !supportsAESGCM { sealGeneric(out, g, nonce, plaintext, data) return } var counter, tagMask [gcmBlockSize]byte if len(nonce) == gcmStandardNonceSize { // Init counter to nonce||1 copy(counter[:], nonce) counter[gcmBlockSize-1] = 1 } else { // Otherwise counter = GHASH(nonce)...