""" Decrypt bytes with AES-CBC using pycryptodome """
return compat_pycrypto_AES.new(key, compat_pycrypto_AES.MODE_CBC, iv).decrypt(data)
+ def aes_gcm_decrypt_and_verify_bytes(data, key, tag, nonce):
+ """ Decrypt bytes with AES-GCM using pycryptodome """
+ return compat_pycrypto_AES.new(key, compat_pycrypto_AES.MODE_GCM, nonce).decrypt_and_verify(data, tag)
+
else:
def aes_cbc_decrypt_bytes(data, key, iv):
""" Decrypt bytes with AES-CBC using native implementation since pycryptodome is unavailable """
return intlist_to_bytes(aes_cbc_decrypt(*map(bytes_to_intlist, (data, key, iv))))
+ def aes_gcm_decrypt_and_verify_bytes(data, key, tag, nonce):
+ """ Decrypt bytes with AES-GCM using native implementation since pycryptodome is unavailable """
+ return intlist_to_bytes(aes_gcm_decrypt_and_verify(*map(bytes_to_intlist, (data, key, tag, nonce))))
+
BLOCK_SIZE_BYTES = 16
-def aes_ctr_decrypt(data, key, counter):
+def aes_ctr_decrypt(data, key, iv):
"""
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
+ @param {int[]} iv 16-Byte initialization vector
@returns {int[]} decrypted data
"""
+ return aes_ctr_encrypt(data, key, iv)
+
+
+def aes_ctr_encrypt(data, key, iv):
+ """
+ Encrypt with aes in counter mode
+
+ @param {int[]} data cleartext
+ @param {int[]} key 16/24/32-Byte cipher key
+ @param {int[]} iv 16-Byte initialization vector
+ @returns {int[]} encrypted data
+ """
expanded_key = key_expansion(key)
block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES))
+ counter = iter_vector(iv)
- decrypted_data = []
+ encrypted_data = []
for i in range(block_count):
- counter_block = counter.next_value()
+ counter_block = next(counter)
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)]
+ encrypted_data += xor(block, cipher_counter_block)
+ encrypted_data = encrypted_data[:len(data)]
- return decrypted_data
+ return encrypted_data
def aes_cbc_decrypt(data, key, iv):
return encrypted_data
-def key_expansion(data):
+def aes_gcm_decrypt_and_verify(data, key, tag, nonce):
"""
- Generate key schedule
+ Decrypt with aes in GBM mode and checks authenticity using tag
- @param {int[]} data 16/24/32-Byte cipher key
- @returns {int[]} 176/208/240-Byte expanded key
+ @param {int[]} data cipher
+ @param {int[]} key 16-Byte cipher key
+ @param {int[]} tag authentication tag
+ @param {int[]} nonce IV (recommended 12-Byte)
+ @returns {int[]} decrypted data
"""
- 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])
+ # XXX: check aes, gcm param
- for _ in range(3):
- temp = data[-4:]
- data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
+ hash_subkey = aes_encrypt([0] * BLOCK_SIZE_BYTES, key_expansion(key))
- if key_size_bytes == 32:
- temp = data[-4:]
- temp = sub_bytes(temp)
- data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
+ if len(nonce) == 12:
+ j0 = nonce + [0, 0, 0, 1]
+ else:
+ fill = (BLOCK_SIZE_BYTES - (len(nonce) % BLOCK_SIZE_BYTES)) % BLOCK_SIZE_BYTES + 8
+ ghash_in = nonce + [0] * fill + bytes_to_intlist((8 * len(nonce)).to_bytes(8, 'big'))
+ j0 = ghash(hash_subkey, ghash_in)
- 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]
+ # TODO: add nonce support to aes_ctr_decrypt
- return data
+ # nonce_ctr = j0[:12]
+ iv_ctr = inc(j0)
+
+ decrypted_data = aes_ctr_decrypt(data, key, iv_ctr + [0] * (BLOCK_SIZE_BYTES - len(iv_ctr)))
+ pad_len = len(data) // 16 * 16
+ s_tag = ghash(
+ hash_subkey,
+ data
+ + [0] * (BLOCK_SIZE_BYTES - len(data) + pad_len) # pad
+ + bytes_to_intlist((0 * 8).to_bytes(8, 'big') # length of associated data
+ + ((len(data) * 8).to_bytes(8, 'big'))) # length of data
+ )
+
+ if tag != aes_ctr_encrypt(s_tag, key, j0):
+ raise ValueError("Mismatching authentication tag")
+
+ return decrypted_data
def aes_encrypt(data, expanded_key):
nonce = data[:NONCE_LENGTH_BYTES]
cipher = data[NONCE_LENGTH_BYTES:]
- class Counter(object):
- __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())
+ decrypted_data = aes_ctr_decrypt(cipher, key, nonce + [0] * (BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES))
plaintext = intlist_to_bytes(decrypted_data)
return plaintext
0x67, 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18, 0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07)
+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 iter_vector(iv):
+ while True:
+ yield iv
+ iv = inc(iv)
+
+
def sub_bytes(data):
return [SBOX[x] for x in data]
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]
return data_shifted
+def shift_block(data):
+ data_shifted = []
+
+ bit = 0
+ for n in data:
+ if bit:
+ n |= 0x100
+ bit = n & 1
+ n >>= 1
+ data_shifted.append(n)
+
+ return data_shifted
+
+
def inc(data):
data = data[:] # copy
for i in range(len(data) - 1, -1, -1):
return data
-__all__ = ['aes_encrypt', 'key_expansion', 'aes_ctr_decrypt', 'aes_cbc_decrypt', 'aes_decrypt_text']
+def block_product(block_x, block_y):
+ # NIST SP 800-38D, Algorithm 1
+
+ if len(block_x) != BLOCK_SIZE_BYTES or len(block_y) != BLOCK_SIZE_BYTES:
+ raise ValueError("Length of blocks need to be %d bytes" % BLOCK_SIZE_BYTES)
+
+ block_r = [0xE1] + [0] * (BLOCK_SIZE_BYTES - 1)
+ block_v = block_y[:]
+ block_z = [0] * BLOCK_SIZE_BYTES
+
+ for i in block_x:
+ for bit in range(7, -1, -1):
+ if i & (1 << bit):
+ block_z = xor(block_z, block_v)
+
+ do_xor = block_v[-1] & 1
+ block_v = shift_block(block_v)
+ if do_xor:
+ block_v = xor(block_v, block_r)
+
+ return block_z
+
+
+def ghash(subkey, data):
+ # NIST SP 800-38D, Algorithm 2
+
+ if len(data) % BLOCK_SIZE_BYTES:
+ raise ValueError("Length of data should be %d bytes" % BLOCK_SIZE_BYTES)
+
+ last_y = [0] * BLOCK_SIZE_BYTES
+ for i in range(0, len(data), BLOCK_SIZE_BYTES):
+ block = data[i : i + BLOCK_SIZE_BYTES] # noqa: E203
+ last_y = block_product(xor(last_y, block), subkey)
+
+ return last_y
+
+
+__all__ = [
+ 'aes_ctr_decrypt',
+ 'aes_cbc_decrypt',
+ 'aes_cbc_decrypt_bytes',
+ 'aes_decrypt_text',
+ 'aes_encrypt',
+ 'aes_gcm_decrypt_and_verify',
+ 'aes_gcm_decrypt_and_verify_bytes',
+ 'key_expansion'
+]
projects / yt-dlp.git / blobdiff