# Author: Trevor Perrin
# See the LICENSE file for legal information regarding use of this file.

"""Abstract class for AES."""


class AES(object):
    def __init__(self, key, mode, IV, implementation):
        if len(key) not in (16, 24, 32):
            raise AssertionError()
        if mode not in [2, 6]:
            raise AssertionError()
        if mode == 2:
            if len(IV) != 16:
                raise AssertionError()
        if mode == 6:
            if len(IV) > 16:
                raise AssertionError()
        self.isBlockCipher = True
        self.isAEAD = False
        self.block_size = 16
        self.implementation = implementation
        if len(key) == 16:
            self.name = "aes128"
        elif len(key) == 24:
            self.name = "aes192"
        elif len(key) == 32:
            self.name = "aes256"
        else:
            raise AssertionError()

    # CBC-Mode encryption, returns ciphertext
    # WARNING: *MAY* modify the input as well
    def encrypt(self, plaintext):
        assert len(plaintext) % 16 == 0

    # CBC-Mode decryption, returns plaintext
    # WARNING: *MAY* modify the input as well
    def decrypt(self, ciphertext):
        assert len(ciphertext) % 16 == 0