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Description:

PyTgCrypto 1.2.7

TgCrypto

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:
def ige256_encrypt(data: bytes, key: bytes, iv: bytes) -> bytes: ...
def ige256_decrypt(data: bytes, key: bytes, iv: bytes) -> bytes: ...

def ctr256_encrypt(data: bytes, key: bytes, iv: bytes, state: bytes) -> bytes: ...
def ctr256_decrypt(data: bytes, key: bytes, iv: bytes, state: bytes) -> bytes: ...

def cbc256_encrypt(data: bytes, key: bytes, iv: bytes) -> bytes: ...
def cbc256_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).
import os

import tgcrypto

data = os.urandom(10 * 1024 * 1024 + 7) # 10 MB of random data + 7 bytes to show padding
key = os.urandom(32) # Random Key
iv = os.urandom(32) # Random IV

# Pad with zeroes: -7 % 16 = 9
data += 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)
import os

import tgcrypto

data = os.urandom(10 * 1024 * 1024) # 10 MB of random data

key = os.urandom(32) # Random Key

enc_iv = bytearray(os.urandom(16)) # Random IV
dec_iv = enc_iv.copy() # Keep a copy for decryption

ctr_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)
import os
from io import BytesIO

import tgcrypto

data = BytesIO(os.urandom(10 * 1024 * 1024)) # 10 MB of random data

key = os.urandom(32) # Random Key

enc_iv = bytearray(os.urandom(16)) # Random IV
dec_iv = enc_iv.copy() # Keep a copy for decryption

enc_state = bytes(1) # Encryption state, starts from 0
dec_state = bytes(1) # Decryption state, starts from 0

encrypted_data = BytesIO() # Encrypted data buffer
decrypted_data = BytesIO() # Decrypted data buffer

while True:
chunk = data.read(1024)

if not chunk:
break

# Write 1K encrypted bytes into the encrypted data buffer
encrypted_data.write(tgcrypto.ctr256_encrypt(chunk, key, enc_iv, enc_state))

# Reset position. We need to read it now
encrypted_data.seek(0)

while True:
chunk = encrypted_data.read(1024)

if not chunk:
break

# Write 1K decrypted bytes into the decrypted data buffer
decrypted_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).
import os

import tgcrypto

data = os.urandom(10 * 1024 * 1024 + 7) # 10 MB of random data + 7 bytes to show padding
key = os.urandom(32) # Random Key

enc_iv = bytearray(os.urandom(16)) # Random IV
dec_iv = enc_iv.copy() # Keep a copy for decryption

# Pad with zeroes: -7 % 16 = 9
data += 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

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

License
LGPLv3+ © 2017-present Dan