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Remove seemingly useless array copies on aes.py (#199)

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Lonami Exo 2017-08-17 18:12:19 +02:00
parent 9f812d83a9
commit afcddfd7c1
1 changed files with 16 additions and 11 deletions
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27
telethon/crypto/aes.py
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@ -5,7 +5,9 @@ import pyaes
class AES: class AES:
@staticmethod @staticmethod
def decrypt_ige(cipher_text, key, iv): def decrypt_ige(cipher_text, key, iv):
"""Decrypts the given text in 16-bytes blocks by using the given key and 32-bytes initialization vector""" """Decrypts the given text in 16-bytes blocks by using the
given key and 32-bytes initialization vector
"""
iv1 = iv[:len(iv) // 2] iv1 = iv[:len(iv) // 2]
iv2 = iv[len(iv) // 2:] iv2 = iv[len(iv) // 2:]
@ -17,8 +19,8 @@ class AES:
cipher_text_block = [0] * 16 cipher_text_block = [0] * 16
for block_index in range(blocks_count): for block_index in range(blocks_count):
for i in range(16): for i in range(16):
cipher_text_block[i] = cipher_text[block_index * 16 + i] ^ iv2[ cipher_text_block[i] = \
i] cipher_text[block_index * 16 + i] ^ iv2[i]
plain_text_block = aes.decrypt(cipher_text_block) plain_text_block = aes.decrypt(cipher_text_block)
@ -26,17 +28,19 @@ class AES:
plain_text_block[i] ^= iv1[i] plain_text_block[i] ^= iv1[i]
iv1 = cipher_text[block_index * 16:block_index * 16 + 16] iv1 = cipher_text[block_index * 16:block_index * 16 + 16]
iv2 = plain_text_block[:] iv2 = plain_text_block
plain_text.extend(plain_text_block[:]) plain_text.extend(plain_text_block)
return bytes(plain_text) return bytes(plain_text)
@staticmethod @staticmethod
def encrypt_ige(plain_text, key, iv): def encrypt_ige(plain_text, key, iv):
"""Encrypts the given text in 16-bytes blocks by using the given key and 32-bytes initialization vector""" """Encrypts the given text in 16-bytes blocks by using the
given key and 32-bytes initialization vector
"""
# Add random padding if and only if it's not evenly divisible by 16 already # Add random padding iff it's not evenly divisible by 16 already
if len(plain_text) % 16 != 0: if len(plain_text) % 16 != 0:
padding_count = 16 - len(plain_text) % 16 padding_count = 16 - len(plain_text) % 16
plain_text += os.urandom(padding_count) plain_text += os.urandom(padding_count)
@ -50,8 +54,9 @@ class AES:
blocks_count = len(plain_text) // 16 blocks_count = len(plain_text) // 16
for block_index in range(blocks_count): for block_index in range(blocks_count):
plain_text_block = list(plain_text[block_index * 16:block_index * plain_text_block = list(
16 + 16]) plain_text[block_index * 16:block_index * 16 + 16]
)
for i in range(16): for i in range(16):
plain_text_block[i] ^= iv1[i] plain_text_block[i] ^= iv1[i]
@ -60,9 +65,9 @@ class AES:
for i in range(16): for i in range(16):
cipher_text_block[i] ^= iv2[i] cipher_text_block[i] ^= iv2[i]
iv1 = cipher_text_block[:] iv1 = cipher_text_block
iv2 = plain_text[block_index * 16:block_index * 16 + 16] iv2 = plain_text[block_index * 16:block_index * 16 + 16]
cipher_text.extend(cipher_text_block[:]) cipher_text.extend(cipher_text_block)
return bytes(cipher_text) return bytes(cipher_text)