aes_gcm.py 文件源码

def change_key(self, master_key):
        if (len(master_key)*8 not in (128, 192, 256)):
            raise InvalidInputException('Error: Master key must be \
                                         128, 192 or 256 bit')

        self.__master_key = master_key
        self.__aes_ecb = AES.new(self.__master_key, AES.MODE_ECB)
        self.__auth_key = bytes_to_long(self.__aes_ecb.encrypt(b'\x00' * 16))

        # precompute the table for multiplication in finite field
        table = []  # for 8-bit
        for i in range(16):
            row = []
            for j in range(256):
                row.append(gf_2_128_mul(self.__auth_key, j << (8 * i)))
            table.append(tuple(row))
        self.__pre_table = tuple(table)

        self.prev_init_value = None  # reset