operation with respect to the initial counter // state: a "fast path" for 96-bit (12-byte) nonces, and a "slow path" // for nonces of other lengths. For a 96-bit nonce, the nonce, along // with a four-byte big-endian counter starting at one, is used // directly as the starting counter. For other nonce sizes, the counter // is computed by passing it through the GHASH function. if len(nonce) == gcmStandardNonceSize { copy(counter[:], nonce) counter[gcmBlockSize-1] = 1 } else { lenBlock := make([]byte,...