tgcrypto/README.md
2019-06-13 00:52:31 +02:00

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# TgCrypto
<img src="https://i.imgur.com/JyxrStE.png" width="160" align="right">
> Fast Telegram Crypto Library for Python
**TgCrypto** is a high-performance, easy-to-install Telegram Crypto Library written in C as a Python extension.
TgCrypto is intended for [Pyrogram](//github.com/pyrogram/pyrogram) and implements the crypto algorithms Telegram
requires, namely:
- **AES256-IGE** - used in [MTProto v2.0](https://core.telegram.org/mtproto).
- **AES256-CTR** - used for [CDN encrypted files](https://core.telegram.org/cdn).
- **AES256-CBC** - used for [encrypted passport credentials](https://core.telegram.org/passport).
## Installation
``` bash
$ pip3 install -U tgcrypto
```
More info: https://docs.pyrogram.org/topics/tgcrypto
## API
TgCrypto API consists of these six methods:
```python
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).
``` python
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)
``` python
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)
``` python
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).
``` python
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
1. Install the package: `pip3 install -U tgcrypto`.
2. Clone this repository: `git clone https://github.com/pyrogram/tgcrypto`.
3. Enter the directory: `cd tgcrypto`.
4. Run tests: `python3 -m unittest`.
**Note**: I haven't found any public test vectors for AES256-IGE, yet.
## License
[LGPLv3+](COPYING.lesser) © 2017-2019 [Dan](https://github.com/delivrance)