mirror of
https://github.com/ytdl-org/youtube-dl
synced 2024-11-27 23:56:51 +01:00
203 lines
7.5 KiB
Python
203 lines
7.5 KiB
Python
__all__ = ['aes_encrypt', 'key_expansion', 'aes_ctr_decrypt', 'aes_decrypt_text']
|
|
|
|
import base64
|
|
from math import ceil
|
|
|
|
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)
|
|
returns the next counter block
|
|
@returns {int[]} decrypted data
|
|
"""
|
|
expanded_key = key_expansion(key)
|
|
block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES))
|
|
|
|
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 += [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 key_expansion(data):
|
|
"""
|
|
Generate key schedule
|
|
|
|
@param {int[]} data 16/24/32-Byte cipher key
|
|
@returns {int[]} 176/208/240-Byte expanded key
|
|
"""
|
|
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])
|
|
|
|
for _ in range(3):
|
|
temp = data[-4:]
|
|
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])
|
|
|
|
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 = 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
|
|
@returns {int[]} 16-Byte cipher
|
|
"""
|
|
rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1
|
|
|
|
data = xor(data, expanded_key[:BLOCK_SIZE_BYTES])
|
|
for i in range(1, rounds+1):
|
|
data = sub_bytes(data)
|
|
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])
|
|
|
|
return data
|
|
|
|
def aes_decrypt_text(data, password, key_size_bytes):
|
|
"""
|
|
Decrypt text
|
|
- The first 8 Bytes of decoded 'data' are the 8 high Bytes of the counter
|
|
- 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)
|
|
SBOX = (0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
|
|
0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
|
|
0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
|
|
0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
|
|
0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
|
|
0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
|
|
0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
|
|
0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
|
|
0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
|
|
0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
|
|
0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
|
|
0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
|
|
0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
|
|
0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
|
|
0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
|
|
0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16)
|
|
MIX_COLUMN_MATRIX = ((2,3,1,1),
|
|
(1,2,3,1),
|
|
(1,1,2,3),
|
|
(3,1,1,2))
|
|
|
|
def sub_bytes(data):
|
|
return [SBOX[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 mix_column(data):
|
|
data_mixed = []
|
|
for row in range(4):
|
|
mixed = 0
|
|
for column in range(4):
|
|
addend = data[column]
|
|
if MIX_COLUMN_MATRIX[row][column] in (2,3):
|
|
addend <<= 1
|
|
if addend > 0xff:
|
|
addend &= 0xff
|
|
addend ^= 0x1b
|
|
if MIX_COLUMN_MATRIX[row][column] == 3:
|
|
addend ^= data[column]
|
|
mixed ^= addend & 0xff
|
|
data_mixed.append(mixed)
|
|
return data_mixed
|
|
|
|
def mix_columns(data):
|
|
data_mixed = []
|
|
for i in range(4):
|
|
column = data[i*4 : (i+1)*4]
|
|
data_mixed += mix_column(column)
|
|
return data_mixed
|
|
|
|
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] )
|
|
return data_shifted
|
|
|
|
def inc(data):
|
|
data = data[:] # copy
|
|
for i in range(len(data)-1,-1,-1):
|
|
if data[i] == 255:
|
|
data[i] = 0
|
|
else:
|
|
data[i] = data[i] + 1
|
|
break
|
|
return data
|