TgCrypto

Note

The implementations of the algorithms presented in this repository are to be considered for educational purposes only.

Fast and Portable Cryptography Extension Library for Pyrogram

TgCrypto is a Cryptography Library written in C as a Python extension. It is designed to be portable, fast, easy to install and use. TgCrypto is intended for Pyrogram and implements the cryptographic algorithms Telegram requires, namely:

• AES-256-IGE - used in MTProto v2.0.
• AES-256-CTR - used for CDN encrypted files.
• AES-256-CBC - used for encrypted passport credentials.

Requirements

• Python 3.7 or higher.

Installation

$ pip3 install -U tgcrypto

API

TgCrypto API consists of these six methods:

defige256_encrypt(data: bytes, key: bytes, iv: bytes) ->bytes: ...
defige256_decrypt(data: bytes, key: bytes, iv: bytes) ->bytes: ...
defctr256_encrypt(data: bytes, key: bytes, iv: bytes, state: bytes) ->bytes: ...
defctr256_decrypt(data: bytes, key: bytes, iv: bytes, state: bytes) ->bytes: ...
defcbc256_encrypt(data: bytes, key: bytes, iv: bytes) ->bytes: ...
defcbc256_decrypt(data: bytes, key: bytes, iv: bytes) ->bytes: ...

Usage

IGE Mode

Note: Data must be padded to match a multiple of the block size (16 bytes).

importosimporttgcryptodata=os.urandom(10*1024*1024+7) # 10 MB of random data + 7 bytes to show paddingkey=os.urandom(32) # Random Keyiv=os.urandom(32) # Random IV# Pad with zeroes: -7 % 16 = 9data+=bytes(-len(data) %16)
ige_encrypted=tgcrypto.ige256_encrypt(data, key, iv)
ige_decrypted=tgcrypto.ige256_decrypt(ige_encrypted, key, iv)
print(data==ige_decrypted) # True

CTR Mode (single chunk)

importosimporttgcryptodata=os.urandom(10*1024*1024) # 10 MB of random datakey=os.urandom(32) # Random Keyenc_iv=bytearray(os.urandom(16)) # Random IVdec_iv=enc_iv.copy() # Keep a copy for decryptionctr_encrypted=tgcrypto.ctr256_encrypt(data, key, enc_iv, bytes(1))
ctr_decrypted=tgcrypto.ctr256_decrypt(ctr_encrypted, key, dec_iv, bytes(1))
print(data==ctr_decrypted) # True

CTR Mode (stream)

importosfromioimportBytesIOimporttgcryptodata=BytesIO(os.urandom(10*1024*1024)) # 10 MB of random datakey=os.urandom(32) # Random Keyenc_iv=bytearray(os.urandom(16)) # Random IVdec_iv=enc_iv.copy() # Keep a copy for decryptionenc_state=bytes(1) # Encryption state, starts from 0dec_state=bytes(1) # Decryption state, starts from 0encrypted_data=BytesIO() # Encrypted data bufferdecrypted_data=BytesIO() # Decrypted data bufferwhileTrue:
chunk=data.read(1024)
ifnotchunk:
break# Write 1K encrypted bytes into the encrypted data bufferencrypted_data.write(tgcrypto.ctr256_encrypt(chunk, key, enc_iv, enc_state))
# Reset position. We need to read it nowencrypted_data.seek(0)
whileTrue:
chunk=encrypted_data.read(1024)
ifnotchunk:
break# Write 1K decrypted bytes into the decrypted data bufferdecrypted_data.write(tgcrypto.ctr256_decrypt(chunk, key, dec_iv, dec_state))
print(data.getvalue() ==decrypted_data.getvalue()) # True

CBC Mode

Note: Data must be padded to match a multiple of the block size (16 bytes).

importosimporttgcryptodata=os.urandom(10*1024*1024+7) # 10 MB of random data + 7 bytes to show paddingkey=os.urandom(32) # Random Keyenc_iv=bytearray(os.urandom(16)) # Random IVdec_iv=enc_iv.copy() # Keep a copy for decryption# Pad with zeroes: -7 % 16 = 9data+=bytes(-len(data) %16)
cbc_encrypted=tgcrypto.cbc256_encrypt(data, key, enc_iv)
cbc_decrypted=tgcrypto.cbc256_decrypt(cbc_encrypted, key, dec_iv)
print(data==cbc_decrypted) # True

Testing

1. Clone this repository: git clone https://github.com/pyrogram/tgcrypto.
2. Enter the directory: cd tgcrypto.
3. Install tox: pip3 install tox
4. Run tests: tox.

License

LGPLv3+ © 2017-present Dan