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https://github.com/LucBerge/yt-dlp.git
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[aes] Add aes_gcm_decrypt_and_verify (#1020)
Authored by: sulyi, pukkandan
This commit is contained in:
Ákos Sülyi
GitHub
parent
a63d9bd0b0
commit
09906f554d
4 changed files with 214 additions and 69 deletions
209
yt_dlp/aes.py
209
yt_dlp/aes.py
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@ -11,39 +11,59 @@ if compat_pycrypto_AES:
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""" Decrypt bytes with AES-CBC using pycryptodome """
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return compat_pycrypto_AES.new(key, compat_pycrypto_AES.MODE_CBC, iv).decrypt(data)
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def aes_gcm_decrypt_and_verify_bytes(data, key, tag, nonce):
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""" Decrypt bytes with AES-GCM using pycryptodome """
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return compat_pycrypto_AES.new(key, compat_pycrypto_AES.MODE_GCM, nonce).decrypt_and_verify(data, tag)
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else:
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def aes_cbc_decrypt_bytes(data, key, iv):
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""" Decrypt bytes with AES-CBC using native implementation since pycryptodome is unavailable """
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return intlist_to_bytes(aes_cbc_decrypt(*map(bytes_to_intlist, (data, key, iv))))
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def aes_gcm_decrypt_and_verify_bytes(data, key, tag, nonce):
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""" Decrypt bytes with AES-GCM using native implementation since pycryptodome is unavailable """
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return intlist_to_bytes(aes_gcm_decrypt_and_verify(*map(bytes_to_intlist, (data, key, tag, nonce))))
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BLOCK_SIZE_BYTES = 16
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def aes_ctr_decrypt(data, key, counter):
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def aes_ctr_decrypt(data, key, iv):
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"""
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Decrypt with aes in counter mode
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@param {int[]} data cipher
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@param {int[]} key 16/24/32-Byte cipher key
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@param {instance} counter Instance whose next_value function (@returns {int[]} 16-Byte block)
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returns the next counter block
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@param {int[]} iv 16-Byte initialization vector
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@returns {int[]} decrypted data
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"""
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return aes_ctr_encrypt(data, key, iv)
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def aes_ctr_encrypt(data, key, iv):
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"""
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Encrypt with aes in counter mode
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@param {int[]} data cleartext
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@param {int[]} key 16/24/32-Byte cipher key
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@param {int[]} iv 16-Byte initialization vector
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@returns {int[]} encrypted data
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"""
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expanded_key = key_expansion(key)
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block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES))
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counter = iter_vector(iv)
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decrypted_data = []
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encrypted_data = []
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for i in range(block_count):
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counter_block = counter.next_value()
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counter_block = next(counter)
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block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES]
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block += [0] * (BLOCK_SIZE_BYTES - len(block))
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cipher_counter_block = aes_encrypt(counter_block, expanded_key)
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decrypted_data += xor(block, cipher_counter_block)
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decrypted_data = decrypted_data[:len(data)]
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encrypted_data += xor(block, cipher_counter_block)
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encrypted_data = encrypted_data[:len(data)]
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return decrypted_data
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return encrypted_data
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def aes_cbc_decrypt(data, key, iv):
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@ -100,39 +120,47 @@ def aes_cbc_encrypt(data, key, iv):
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return encrypted_data
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def key_expansion(data):
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def aes_gcm_decrypt_and_verify(data, key, tag, nonce):
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"""
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Generate key schedule
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Decrypt with aes in GBM mode and checks authenticity using tag
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@param {int[]} data 16/24/32-Byte cipher key
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@returns {int[]} 176/208/240-Byte expanded key
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@param {int[]} data cipher
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@param {int[]} key 16-Byte cipher key
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@param {int[]} tag authentication tag
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@param {int[]} nonce IV (recommended 12-Byte)
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@returns {int[]} decrypted data
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"""
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data = data[:] # copy
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rcon_iteration = 1
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key_size_bytes = len(data)
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expanded_key_size_bytes = (key_size_bytes // 4 + 7) * BLOCK_SIZE_BYTES
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while len(data) < expanded_key_size_bytes:
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temp = data[-4:]
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temp = key_schedule_core(temp, rcon_iteration)
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rcon_iteration += 1
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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# XXX: check aes, gcm param
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for _ in range(3):
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temp = data[-4:]
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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hash_subkey = aes_encrypt([0] * BLOCK_SIZE_BYTES, key_expansion(key))
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if key_size_bytes == 32:
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temp = data[-4:]
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temp = sub_bytes(temp)
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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if len(nonce) == 12:
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j0 = nonce + [0, 0, 0, 1]
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else:
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fill = (BLOCK_SIZE_BYTES - (len(nonce) % BLOCK_SIZE_BYTES)) % BLOCK_SIZE_BYTES + 8
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ghash_in = nonce + [0] * fill + bytes_to_intlist((8 * len(nonce)).to_bytes(8, 'big'))
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j0 = ghash(hash_subkey, ghash_in)
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for _ in range(3 if key_size_bytes == 32 else 2 if key_size_bytes == 24 else 0):
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temp = data[-4:]
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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data = data[:expanded_key_size_bytes]
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# TODO: add nonce support to aes_ctr_decrypt
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return data
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# nonce_ctr = j0[:12]
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iv_ctr = inc(j0)
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decrypted_data = aes_ctr_decrypt(data, key, iv_ctr + [0] * (BLOCK_SIZE_BYTES - len(iv_ctr)))
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pad_len = len(data) // 16 * 16
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s_tag = ghash(
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hash_subkey,
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data
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+ [0] * (BLOCK_SIZE_BYTES - len(data) + pad_len) # pad
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+ bytes_to_intlist((0 * 8).to_bytes(8, 'big') # length of associated data
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+ ((len(data) * 8).to_bytes(8, 'big'))) # length of data
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)
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if tag != aes_ctr_encrypt(s_tag, key, j0):
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raise ValueError("Mismatching authentication tag")
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return decrypted_data
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def aes_encrypt(data, expanded_key):
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@ -201,15 +229,7 @@ def aes_decrypt_text(data, password, key_size_bytes):
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nonce = data[:NONCE_LENGTH_BYTES]
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cipher = data[NONCE_LENGTH_BYTES:]
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class Counter(object):
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__value = nonce + [0] * (BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES)
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def next_value(self):
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temp = self.__value
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self.__value = inc(self.__value)
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return temp
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decrypted_data = aes_ctr_decrypt(cipher, key, Counter())
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decrypted_data = aes_ctr_decrypt(cipher, key, nonce + [0] * (BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES))
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plaintext = intlist_to_bytes(decrypted_data)
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return plaintext
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@ -290,6 +310,47 @@ RIJNDAEL_LOG_TABLE = (0x00, 0x00, 0x19, 0x01, 0x32, 0x02, 0x1a, 0xc6, 0x4b, 0xc7
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0x67, 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18, 0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07)
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def key_expansion(data):
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"""
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Generate key schedule
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@param {int[]} data 16/24/32-Byte cipher key
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@returns {int[]} 176/208/240-Byte expanded key
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"""
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data = data[:] # copy
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rcon_iteration = 1
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key_size_bytes = len(data)
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expanded_key_size_bytes = (key_size_bytes // 4 + 7) * BLOCK_SIZE_BYTES
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while len(data) < expanded_key_size_bytes:
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temp = data[-4:]
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temp = key_schedule_core(temp, rcon_iteration)
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rcon_iteration += 1
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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for _ in range(3):
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temp = data[-4:]
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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if key_size_bytes == 32:
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temp = data[-4:]
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temp = sub_bytes(temp)
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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for _ in range(3 if key_size_bytes == 32 else 2 if key_size_bytes == 24 else 0):
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temp = data[-4:]
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data += xor(temp, data[-key_size_bytes: 4 - key_size_bytes])
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data = data[:expanded_key_size_bytes]
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return data
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def iter_vector(iv):
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while True:
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yield iv
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iv = inc(iv)
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def sub_bytes(data):
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return [SBOX[x] for x in data]
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@ -315,7 +376,7 @@ def xor(data1, data2):
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def rijndael_mul(a, b):
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if(a == 0 or b == 0):
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if a == 0 or b == 0:
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return 0
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return RIJNDAEL_EXP_TABLE[(RIJNDAEL_LOG_TABLE[a] + RIJNDAEL_LOG_TABLE[b]) % 0xFF]
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@ -359,6 +420,20 @@ def shift_rows_inv(data):
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return data_shifted
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def shift_block(data):
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data_shifted = []
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bit = 0
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for n in data:
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if bit:
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n |= 0x100
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bit = n & 1
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n >>= 1
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data_shifted.append(n)
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return data_shifted
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def inc(data):
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data = data[:] # copy
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for i in range(len(data) - 1, -1, -1):
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@ -370,4 +445,50 @@ def inc(data):
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return data
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__all__ = ['aes_encrypt', 'key_expansion', 'aes_ctr_decrypt', 'aes_cbc_decrypt', 'aes_decrypt_text']
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def block_product(block_x, block_y):
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# NIST SP 800-38D, Algorithm 1
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if len(block_x) != BLOCK_SIZE_BYTES or len(block_y) != BLOCK_SIZE_BYTES:
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raise ValueError("Length of blocks need to be %d bytes" % BLOCK_SIZE_BYTES)
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block_r = [0xE1] + [0] * (BLOCK_SIZE_BYTES - 1)
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block_v = block_y[:]
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block_z = [0] * BLOCK_SIZE_BYTES
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for i in block_x:
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for bit in range(7, -1, -1):
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if i & (1 << bit):
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block_z = xor(block_z, block_v)
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do_xor = block_v[-1] & 1
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block_v = shift_block(block_v)
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if do_xor:
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block_v = xor(block_v, block_r)
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return block_z
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def ghash(subkey, data):
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# NIST SP 800-38D, Algorithm 2
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if len(data) % BLOCK_SIZE_BYTES:
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raise ValueError("Length of data should be %d bytes" % BLOCK_SIZE_BYTES)
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last_y = [0] * BLOCK_SIZE_BYTES
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for i in range(0, len(data), BLOCK_SIZE_BYTES):
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block = data[i : i + BLOCK_SIZE_BYTES] # noqa: E203
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last_y = block_product(xor(last_y, block), subkey)
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return last_y
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__all__ = [
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'aes_ctr_decrypt',
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'aes_cbc_decrypt',
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'aes_cbc_decrypt_bytes',
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'aes_decrypt_text',
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'aes_encrypt',
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'aes_gcm_decrypt_and_verify',
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'aes_gcm_decrypt_and_verify_bytes',
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'key_expansion'
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]
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