_ Git - youtube-dl/blob - youtube_dl/aes.py

   1 from __future__ import unicode_literals
   2
   3 from math import ceil
   4
   5 from .compat import compat_b64decode
   6 from .utils import bytes_to_intlist, intlist_to_bytes
   7
   8 BLOCK_SIZE_BYTES = 16
   9
  10
  11 def aes_ctr_decrypt(data, key, counter):
  12     """
  13     Decrypt with aes in counter mode
  14
  15     @param {int[]} data        cipher
  16     @param {int[]} key         16/24/32-Byte cipher key
  17     @param {instance} counter  Instance whose next_value function (@returns {int[]}  16-Byte block)
  18                                returns the next counter block
  19     @returns {int[]}           decrypted data
  20     """
  21     expanded_key = key_expansion(key)
  22     block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES))
  23
  24     decrypted_data = []
  25     for i in range(block_count):
  26         counter_block = counter.next_value()
  27         block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES]
  28         block += [0] * (BLOCK_SIZE_BYTES - len(block))
  29
  30         cipher_counter_block = aes_encrypt(counter_block, expanded_key)
  31         decrypted_data += xor(block, cipher_counter_block)
  32     decrypted_data = decrypted_data[:len(data)]
  33
  34     return decrypted_data
  35
  36
  37 def aes_cbc_decrypt(data, key, iv):
  38     """
  39     Decrypt with aes in CBC mode
  40
  41     @param {int[]} data        cipher
  42     @param {int[]} key         16/24/32-Byte cipher key
  43     @param {int[]} iv          16-Byte IV
  44     @returns {int[]}           decrypted data
  45     """
  46     expanded_key = key_expansion(key)
  47     block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES))
  48
  49     decrypted_data = []
  50     previous_cipher_block = iv
  51     for i in range(block_count):
  52         block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES]
  53         block += [0] * (BLOCK_SIZE_BYTES - len(block))
  54
  55         decrypted_block = aes_decrypt(block, expanded_key)
  56         decrypted_data += xor(decrypted_block, previous_cipher_block)
  57         previous_cipher_block = block
  58     decrypted_data = decrypted_data[:len(data)]
  59
  60     return decrypted_data
  61
  62
  63 def aes_cbc_encrypt(data, key, iv):
  64     """
  65     Encrypt with aes in CBC mode. Using PKCS#7 padding
  66
  67     @param {int[]} data        cleartext
  68     @param {int[]} key         16/24/32-Byte cipher key
  69     @param {int[]} iv          16-Byte IV
  70     @returns {int[]}           encrypted data
  71     """
  72     expanded_key = key_expansion(key)
  73     block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES))
  74
  75     encrypted_data = []
  76     previous_cipher_block = iv
  77     for i in range(block_count):
  78         block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES]
  79         remaining_length = BLOCK_SIZE_BYTES - len(block)
  80         block += [remaining_length] * remaining_length
  81         mixed_block = xor(block, previous_cipher_block)
  82
  83         encrypted_block = aes_encrypt(mixed_block, expanded_key)
  84         encrypted_data += encrypted_block
  85
  86         previous_cipher_block = encrypted_block
  87
  88     return encrypted_data
  89
  90
  91 def key_expansion(data):
  92     """
  93     Generate key schedule
  94
  95     @param {int[]} data  16/24/32-Byte cipher key
  96     @returns {int[]}     176/208/240-Byte expanded key
  97     """
  98     data = data[:]  # copy
  99     rcon_iteration = 1
 100     key_size_bytes = len(data)
 101     expanded_key_size_bytes = (key_size_bytes // 4 + 7) * BLOCK_SIZE_BYTES
 102
 103     while len(data) < expanded_key_size_bytes:
 104         temp = data[-4:]
 105         temp = key_schedule_core(temp, rcon_iteration)
 106         rcon_iteration += 1
 107         data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
 108
 109         for _ in range(3):
 110             temp = data[-4:]
 111             data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
 112
 113         if key_size_bytes == 32:
 114             temp = data[-4:]
 115             temp = sub_bytes(temp)
 116             data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
 117
 118         for _ in range(3 if key_size_bytes == 32 else 2 if key_size_bytes == 24 else 0):
 119             temp = data[-4:]
 120             data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
 121     data = data[:expanded_key_size_bytes]
 122
 123     return data
 124
 125
 126 def aes_encrypt(data, expanded_key):
 127     """
 128     Encrypt one block with aes
 129
 130     @param {int[]} data          16-Byte state
 131     @param {int[]} expanded_key  176/208/240-Byte expanded key
 132     @returns {int[]}             16-Byte cipher
 133     """
 134     rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1
 135
 136     data = xor(data, expanded_key[:BLOCK_SIZE_BYTES])
 137     for i in range(1, rounds + 1):
 138         data = sub_bytes(data)
 139         data = shift_rows(data)
 140         if i != rounds:
 141             data = mix_columns(data)
 142         data = xor(data, expanded_key[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES])
 143
 144     return data
 145
 146
 147 def aes_decrypt(data, expanded_key):
 148     """
 149     Decrypt one block with aes
 150
 151     @param {int[]} data          16-Byte cipher
 152     @param {int[]} expanded_key  176/208/240-Byte expanded key
 153     @returns {int[]}             16-Byte state
 154     """
 155     rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1
 156
 157     for i in range(rounds, 0, -1):
 158         data = xor(data, expanded_key[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES])
 159         if i != rounds:
 160             data = mix_columns_inv(data)
 161         data = shift_rows_inv(data)
 162         data = sub_bytes_inv(data)
 163     data = xor(data, expanded_key[:BLOCK_SIZE_BYTES])
 164
 165     return data
 166
 167
 168 def aes_decrypt_text(data, password, key_size_bytes):
 169     """
 170     Decrypt text
 171     - The first 8 Bytes of decoded 'data' are the 8 high Bytes of the counter
 172     - The cipher key is retrieved by encrypting the first 16 Byte of 'password'
 173       with the first 'key_size_bytes' Bytes from 'password' (if necessary filled with 0's)
 174     - Mode of operation is 'counter'
 175
 176     @param {str} data                    Base64 encoded string
 177     @param {str,unicode} password        Password (will be encoded with utf-8)
 178     @param {int} key_size_bytes          Possible values: 16 for 128-Bit, 24 for 192-Bit or 32 for 256-Bit
 179     @returns {str}                       Decrypted data
 180     """
 181     NONCE_LENGTH_BYTES = 8
 182
 183     data = bytes_to_intlist(compat_b64decode(data))
 184     password = bytes_to_intlist(password.encode('utf-8'))
 185
 186     key = password[:key_size_bytes] + [0] * (key_size_bytes - len(password))
 187     key = aes_encrypt(key[:BLOCK_SIZE_BYTES], key_expansion(key)) * (key_size_bytes // BLOCK_SIZE_BYTES)
 188
 189     nonce = data[:NONCE_LENGTH_BYTES]
 190     cipher = data[NONCE_LENGTH_BYTES:]
 191
 192     class Counter(object):
 193         __value = nonce + [0] * (BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES)
 194
 195         def next_value(self):
 196             temp = self.__value
 197             self.__value = inc(self.__value)
 198             return temp
 199
 200     decrypted_data = aes_ctr_decrypt(cipher, key, Counter())
 201     plaintext = intlist_to_bytes(decrypted_data)
 202
 203     return plaintext
 204
 205
 206 RCON = (0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36)
 207 SBOX = (0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
 208         0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
 209         0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
 210         0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
 211         0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
 212         0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
 213         0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
 214         0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
 215         0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
 216         0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
 217         0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
 218         0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
 219         0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
 220         0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
 221         0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
 222         0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16)
 223 SBOX_INV = (0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
 224             0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
 225             0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
 226             0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
 227             0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
 228             0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
 229             0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
 230             0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
 231             0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
 232             0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
 233             0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
 234             0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
 235             0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
 236             0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
 237             0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
 238             0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d)
 239 MIX_COLUMN_MATRIX = ((0x2, 0x3, 0x1, 0x1),
 240                      (0x1, 0x2, 0x3, 0x1),
 241                      (0x1, 0x1, 0x2, 0x3),
 242                      (0x3, 0x1, 0x1, 0x2))
 243 MIX_COLUMN_MATRIX_INV = ((0xE, 0xB, 0xD, 0x9),
 244                          (0x9, 0xE, 0xB, 0xD),
 245                          (0xD, 0x9, 0xE, 0xB),
 246                          (0xB, 0xD, 0x9, 0xE))
 247 RIJNDAEL_EXP_TABLE = (0x01, 0x03, 0x05, 0x0F, 0x11, 0x33, 0x55, 0xFF, 0x1A, 0x2E, 0x72, 0x96, 0xA1, 0xF8, 0x13, 0x35,
 248                       0x5F, 0xE1, 0x38, 0x48, 0xD8, 0x73, 0x95, 0xA4, 0xF7, 0x02, 0x06, 0x0A, 0x1E, 0x22, 0x66, 0xAA,
 249                       0xE5, 0x34, 0x5C, 0xE4, 0x37, 0x59, 0xEB, 0x26, 0x6A, 0xBE, 0xD9, 0x70, 0x90, 0xAB, 0xE6, 0x31,
 250                       0x53, 0xF5, 0x04, 0x0C, 0x14, 0x3C, 0x44, 0xCC, 0x4F, 0xD1, 0x68, 0xB8, 0xD3, 0x6E, 0xB2, 0xCD,
 251                       0x4C, 0xD4, 0x67, 0xA9, 0xE0, 0x3B, 0x4D, 0xD7, 0x62, 0xA6, 0xF1, 0x08, 0x18, 0x28, 0x78, 0x88,
 252                       0x83, 0x9E, 0xB9, 0xD0, 0x6B, 0xBD, 0xDC, 0x7F, 0x81, 0x98, 0xB3, 0xCE, 0x49, 0xDB, 0x76, 0x9A,
 253                       0xB5, 0xC4, 0x57, 0xF9, 0x10, 0x30, 0x50, 0xF0, 0x0B, 0x1D, 0x27, 0x69, 0xBB, 0xD6, 0x61, 0xA3,
 254                       0xFE, 0x19, 0x2B, 0x7D, 0x87, 0x92, 0xAD, 0xEC, 0x2F, 0x71, 0x93, 0xAE, 0xE9, 0x20, 0x60, 0xA0,
 255                       0xFB, 0x16, 0x3A, 0x4E, 0xD2, 0x6D, 0xB7, 0xC2, 0x5D, 0xE7, 0x32, 0x56, 0xFA, 0x15, 0x3F, 0x41,
 256                       0xC3, 0x5E, 0xE2, 0x3D, 0x47, 0xC9, 0x40, 0xC0, 0x5B, 0xED, 0x2C, 0x74, 0x9C, 0xBF, 0xDA, 0x75,
 257                       0x9F, 0xBA, 0xD5, 0x64, 0xAC, 0xEF, 0x2A, 0x7E, 0x82, 0x9D, 0xBC, 0xDF, 0x7A, 0x8E, 0x89, 0x80,
 258                       0x9B, 0xB6, 0xC1, 0x58, 0xE8, 0x23, 0x65, 0xAF, 0xEA, 0x25, 0x6F, 0xB1, 0xC8, 0x43, 0xC5, 0x54,
 259                       0xFC, 0x1F, 0x21, 0x63, 0xA5, 0xF4, 0x07, 0x09, 0x1B, 0x2D, 0x77, 0x99, 0xB0, 0xCB, 0x46, 0xCA,
 260                       0x45, 0xCF, 0x4A, 0xDE, 0x79, 0x8B, 0x86, 0x91, 0xA8, 0xE3, 0x3E, 0x42, 0xC6, 0x51, 0xF3, 0x0E,
 261                       0x12, 0x36, 0x5A, 0xEE, 0x29, 0x7B, 0x8D, 0x8C, 0x8F, 0x8A, 0x85, 0x94, 0xA7, 0xF2, 0x0D, 0x17,
 262                       0x39, 0x4B, 0xDD, 0x7C, 0x84, 0x97, 0xA2, 0xFD, 0x1C, 0x24, 0x6C, 0xB4, 0xC7, 0x52, 0xF6, 0x01)
 263 RIJNDAEL_LOG_TABLE = (0x00, 0x00, 0x19, 0x01, 0x32, 0x02, 0x1a, 0xc6, 0x4b, 0xc7, 0x1b, 0x68, 0x33, 0xee, 0xdf, 0x03,
 264                       0x64, 0x04, 0xe0, 0x0e, 0x34, 0x8d, 0x81, 0xef, 0x4c, 0x71, 0x08, 0xc8, 0xf8, 0x69, 0x1c, 0xc1,
 265                       0x7d, 0xc2, 0x1d, 0xb5, 0xf9, 0xb9, 0x27, 0x6a, 0x4d, 0xe4, 0xa6, 0x72, 0x9a, 0xc9, 0x09, 0x78,
 266                       0x65, 0x2f, 0x8a, 0x05, 0x21, 0x0f, 0xe1, 0x24, 0x12, 0xf0, 0x82, 0x45, 0x35, 0x93, 0xda, 0x8e,
 267                       0x96, 0x8f, 0xdb, 0xbd, 0x36, 0xd0, 0xce, 0x94, 0x13, 0x5c, 0xd2, 0xf1, 0x40, 0x46, 0x83, 0x38,
 268                       0x66, 0xdd, 0xfd, 0x30, 0xbf, 0x06, 0x8b, 0x62, 0xb3, 0x25, 0xe2, 0x98, 0x22, 0x88, 0x91, 0x10,
 269                       0x7e, 0x6e, 0x48, 0xc3, 0xa3, 0xb6, 0x1e, 0x42, 0x3a, 0x6b, 0x28, 0x54, 0xfa, 0x85, 0x3d, 0xba,
 270                       0x2b, 0x79, 0x0a, 0x15, 0x9b, 0x9f, 0x5e, 0xca, 0x4e, 0xd4, 0xac, 0xe5, 0xf3, 0x73, 0xa7, 0x57,
 271                       0xaf, 0x58, 0xa8, 0x50, 0xf4, 0xea, 0xd6, 0x74, 0x4f, 0xae, 0xe9, 0xd5, 0xe7, 0xe6, 0xad, 0xe8,
 272                       0x2c, 0xd7, 0x75, 0x7a, 0xeb, 0x16, 0x0b, 0xf5, 0x59, 0xcb, 0x5f, 0xb0, 0x9c, 0xa9, 0x51, 0xa0,
 273                       0x7f, 0x0c, 0xf6, 0x6f, 0x17, 0xc4, 0x49, 0xec, 0xd8, 0x43, 0x1f, 0x2d, 0xa4, 0x76, 0x7b, 0xb7,
 274                       0xcc, 0xbb, 0x3e, 0x5a, 0xfb, 0x60, 0xb1, 0x86, 0x3b, 0x52, 0xa1, 0x6c, 0xaa, 0x55, 0x29, 0x9d,
 275                       0x97, 0xb2, 0x87, 0x90, 0x61, 0xbe, 0xdc, 0xfc, 0xbc, 0x95, 0xcf, 0xcd, 0x37, 0x3f, 0x5b, 0xd1,
 276                       0x53, 0x39, 0x84, 0x3c, 0x41, 0xa2, 0x6d, 0x47, 0x14, 0x2a, 0x9e, 0x5d, 0x56, 0xf2, 0xd3, 0xab,
 277                       0x44, 0x11, 0x92, 0xd9, 0x23, 0x20, 0x2e, 0x89, 0xb4, 0x7c, 0xb8, 0x26, 0x77, 0x99, 0xe3, 0xa5,
 278                       0x67, 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18, 0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07)
 279
 280
 281 def sub_bytes(data):
 282     return [SBOX[x] for x in data]
 283
 284
 285 def sub_bytes_inv(data):
 286     return [SBOX_INV[x] for x in data]
 287
 288
 289 def rotate(data):
 290     return data[1:] + [data[0]]
 291
 292
 293 def key_schedule_core(data, rcon_iteration):
 294     data = rotate(data)
 295     data = sub_bytes(data)
 296     data[0] = data[0] ^ RCON[rcon_iteration]
 297
 298     return data
 299
 300
 301 def xor(data1, data2):
 302     return [x ^ y for x, y in zip(data1, data2)]
 303
 304
 305 def rijndael_mul(a, b):
 306     if(a == 0 or b == 0):
 307         return 0
 308     return RIJNDAEL_EXP_TABLE[(RIJNDAEL_LOG_TABLE[a] + RIJNDAEL_LOG_TABLE[b]) % 0xFF]
 309
 310
 311 def mix_column(data, matrix):
 312     data_mixed = []
 313     for row in range(4):
 314         mixed = 0
 315         for column in range(4):
 316             # xor is (+) and (-)
 317             mixed ^= rijndael_mul(data[column], matrix[row][column])
 318         data_mixed.append(mixed)
 319     return data_mixed
 320
 321
 322 def mix_columns(data, matrix=MIX_COLUMN_MATRIX):
 323     data_mixed = []
 324     for i in range(4):
 325         column = data[i * 4: (i + 1) * 4]
 326         data_mixed += mix_column(column, matrix)
 327     return data_mixed
 328
 329
 330 def mix_columns_inv(data):
 331     return mix_columns(data, MIX_COLUMN_MATRIX_INV)
 332
 333
 334 def shift_rows(data):
 335     data_shifted = []
 336     for column in range(4):
 337         for row in range(4):
 338             data_shifted.append(data[((column + row) & 0b11) * 4 + row])
 339     return data_shifted
 340
 341
 342 def shift_rows_inv(data):
 343     data_shifted = []
 344     for column in range(4):
 345         for row in range(4):
 346             data_shifted.append(data[((column - row) & 0b11) * 4 + row])
 347     return data_shifted
 348
 349
 350 def inc(data):
 351     data = data[:]  # copy
 352     for i in range(len(data) - 1, -1, -1):
 353         if data[i] == 255:
 354             data[i] = 0
 355         else:
 356             data[i] = data[i] + 1
 357             break
 358     return data
 359
 360
 361 __all__ = ['aes_encrypt', 'key_expansion', 'aes_ctr_decrypt', 'aes_cbc_decrypt', 'aes_decrypt_text']