diff options
Diffstat (limited to 'youtube_dl/aes.py')
| -rw-r--r-- | youtube_dl/aes.py | 125 |
1 files changed, 72 insertions, 53 deletions
diff --git a/youtube_dl/aes.py b/youtube_dl/aes.py index e9c5e2152..ccfd73770 100644 --- a/youtube_dl/aes.py +++ b/youtube_dl/aes.py @@ -7,10 +7,11 @@ from .utils import bytes_to_intlist, intlist_to_bytes BLOCK_SIZE_BYTES = 16 + def aes_ctr_decrypt(data, key, counter): """ Decrypt with aes in counter mode - + @param {int[]} data cipher @param {int[]} key 16/24/32-Byte cipher key @param {instance} counter Instance whose next_value function (@returns {int[]} 16-Byte block) @@ -19,23 +20,24 @@ def aes_ctr_decrypt(data, key, counter): """ expanded_key = key_expansion(key) block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) - - decrypted_data=[] + + decrypted_data = [] for i in range(block_count): counter_block = counter.next_value() - block = data[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES] + block = data[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES] block += [0]*(BLOCK_SIZE_BYTES - len(block)) - + cipher_counter_block = aes_encrypt(counter_block, expanded_key) decrypted_data += xor(block, cipher_counter_block) decrypted_data = decrypted_data[:len(data)] - + return decrypted_data + def aes_cbc_decrypt(data, key, iv): """ Decrypt with aes in CBC mode - + @param {int[]} data cipher @param {int[]} key 16/24/32-Byte cipher key @param {int[]} iv 16-Byte IV @@ -43,60 +45,62 @@ def aes_cbc_decrypt(data, key, iv): """ expanded_key = key_expansion(key) block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) - - decrypted_data=[] + + decrypted_data = [] previous_cipher_block = iv for i in range(block_count): - block = data[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES] + block = data[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES] block += [0]*(BLOCK_SIZE_BYTES - len(block)) - + decrypted_block = aes_decrypt(block, expanded_key) decrypted_data += xor(decrypted_block, previous_cipher_block) previous_cipher_block = block decrypted_data = decrypted_data[:len(data)] - + return decrypted_data + def key_expansion(data): """ Generate key schedule - + @param {int[]} data 16/24/32-Byte cipher key - @returns {int[]} 176/208/240-Byte expanded key + @returns {int[]} 176/208/240-Byte expanded key """ - data = data[:] # copy + data = data[:] # copy rcon_iteration = 1 key_size_bytes = len(data) expanded_key_size_bytes = (key_size_bytes // 4 + 7) * BLOCK_SIZE_BYTES - + while len(data) < expanded_key_size_bytes: temp = data[-4:] temp = key_schedule_core(temp, rcon_iteration) rcon_iteration += 1 - data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) - + data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) + for _ in range(3): temp = data[-4:] - data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) - + data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) + if key_size_bytes == 32: temp = data[-4:] temp = sub_bytes(temp) - data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) - + data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) + for _ in range(3 if key_size_bytes == 32 else 2 if key_size_bytes == 24 else 0): temp = data[-4:] - data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) + data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) data = data[:expanded_key_size_bytes] - + return data + def aes_encrypt(data, expanded_key): """ Encrypt one block with aes - + @param {int[]} data 16-Byte state - @param {int[]} expanded_key 176/208/240-Byte expanded key + @param {int[]} expanded_key 176/208/240-Byte expanded key @returns {int[]} 16-Byte cipher """ rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1 @@ -107,30 +111,32 @@ def aes_encrypt(data, expanded_key): data = shift_rows(data) if i != rounds: data = mix_columns(data) - data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES]) + data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES]) return data + def aes_decrypt(data, expanded_key): """ Decrypt one block with aes - + @param {int[]} data 16-Byte cipher @param {int[]} expanded_key 176/208/240-Byte expanded key @returns {int[]} 16-Byte state """ rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1 - + for i in range(rounds, 0, -1): - data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES]) + data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES]) if i != rounds: data = mix_columns_inv(data) data = shift_rows_inv(data) data = sub_bytes_inv(data) data = xor(data, expanded_key[:BLOCK_SIZE_BYTES]) - + return data + def aes_decrypt_text(data, password, key_size_bytes): """ Decrypt text @@ -138,33 +144,34 @@ def aes_decrypt_text(data, password, key_size_bytes): - The cipher key is retrieved by encrypting the first 16 Byte of 'password' with the first 'key_size_bytes' Bytes from 'password' (if necessary filled with 0's) - Mode of operation is 'counter' - + @param {str} data Base64 encoded string @param {str,unicode} password Password (will be encoded with utf-8) @param {int} key_size_bytes Possible values: 16 for 128-Bit, 24 for 192-Bit or 32 for 256-Bit @returns {str} Decrypted data """ NONCE_LENGTH_BYTES = 8 - + data = bytes_to_intlist(base64.b64decode(data)) password = bytes_to_intlist(password.encode('utf-8')) - + key = password[:key_size_bytes] + [0]*(key_size_bytes - len(password)) key = aes_encrypt(key[:BLOCK_SIZE_BYTES], key_expansion(key)) * (key_size_bytes // BLOCK_SIZE_BYTES) - + nonce = data[:NONCE_LENGTH_BYTES] cipher = data[NONCE_LENGTH_BYTES:] - + class Counter: __value = nonce + [0]*(BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES) + def next_value(self): temp = self.__value self.__value = inc(self.__value) return temp - + decrypted_data = aes_ctr_decrypt(cipher, key, Counter()) plaintext = intlist_to_bytes(decrypted_data) - + return plaintext RCON = (0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36) @@ -200,14 +207,14 @@ SBOX_INV = (0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d) -MIX_COLUMN_MATRIX = ((0x2,0x3,0x1,0x1), - (0x1,0x2,0x3,0x1), - (0x1,0x1,0x2,0x3), - (0x3,0x1,0x1,0x2)) -MIX_COLUMN_MATRIX_INV = ((0xE,0xB,0xD,0x9), - (0x9,0xE,0xB,0xD), - (0xD,0x9,0xE,0xB), - (0xB,0xD,0x9,0xE)) +MIX_COLUMN_MATRIX = ((0x2, 0x3, 0x1, 0x1), + (0x1, 0x2, 0x3, 0x1), + (0x1, 0x1, 0x2, 0x3), + (0x3, 0x1, 0x1, 0x2)) +MIX_COLUMN_MATRIX_INV = ((0xE, 0xB, 0xD, 0x9), + (0x9, 0xE, 0xB, 0xD), + (0xD, 0x9, 0xE, 0xB), + (0xB, 0xD, 0x9, 0xE)) RIJNDAEL_EXP_TABLE = (0x01, 0x03, 0x05, 0x0F, 0x11, 0x33, 0x55, 0xFF, 0x1A, 0x2E, 0x72, 0x96, 0xA1, 0xF8, 0x13, 0x35, 0x5F, 0xE1, 0x38, 0x48, 0xD8, 0x73, 0x95, 0xA4, 0xF7, 0x02, 0x06, 0x0A, 0x1E, 0x22, 0x66, 0xAA, 0xE5, 0x34, 0x5C, 0xE4, 0x37, 0x59, 0xEB, 0x26, 0x6A, 0xBE, 0xD9, 0x70, 0x90, 0xAB, 0xE6, 0x31, @@ -241,30 +248,37 @@ RIJNDAEL_LOG_TABLE = (0x00, 0x00, 0x19, 0x01, 0x32, 0x02, 0x1a, 0xc6, 0x4b, 0xc7 0x44, 0x11, 0x92, 0xd9, 0x23, 0x20, 0x2e, 0x89, 0xb4, 0x7c, 0xb8, 0x26, 0x77, 0x99, 0xe3, 0xa5, 0x67, 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18, 0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07) + def sub_bytes(data): return [SBOX[x] for x in data] + def sub_bytes_inv(data): return [SBOX_INV[x] for x in data] + def rotate(data): return data[1:] + [data[0]] + def key_schedule_core(data, rcon_iteration): data = rotate(data) data = sub_bytes(data) data[0] = data[0] ^ RCON[rcon_iteration] - + return data + def xor(data1, data2): return [x^y for x, y in zip(data1, data2)] + def rijndael_mul(a, b): - if(a==0 or b==0): + if(a == 0 or b == 0): return 0 return RIJNDAEL_EXP_TABLE[(RIJNDAEL_LOG_TABLE[a] + RIJNDAEL_LOG_TABLE[b]) % 0xFF] + def mix_column(data, matrix): data_mixed = [] for row in range(4): @@ -275,33 +289,38 @@ def mix_column(data, matrix): data_mixed.append(mixed) return data_mixed + def mix_columns(data, matrix=MIX_COLUMN_MATRIX): data_mixed = [] for i in range(4): - column = data[i*4 : (i+1)*4] + column = data[i*4: (i+1)*4] data_mixed += mix_column(column, matrix) return data_mixed + def mix_columns_inv(data): return mix_columns(data, MIX_COLUMN_MATRIX_INV) + def shift_rows(data): data_shifted = [] for column in range(4): for row in range(4): - data_shifted.append( data[((column + row) & 0b11) * 4 + row] ) + data_shifted.append(data[((column + row) & 0b11) * 4 + row]) return data_shifted + def shift_rows_inv(data): data_shifted = [] for column in range(4): for row in range(4): - data_shifted.append( data[((column - row) & 0b11) * 4 + row] ) + data_shifted.append(data[((column - row) & 0b11) * 4 + row]) return data_shifted + def inc(data): - data = data[:] # copy - for i in range(len(data)-1,-1,-1): + data = data[:] # copy + for i in range(len(data)-1, -1, -1): if data[i] == 255: data[i] = 0 else: |