xtea_cython

High-performance XTEA encryption implementation using Cython. Drop-in replacement for the PyPI xtea library.

Installation

pip install xtea_cython

Requirements: Python 3.8+, no runtime dependencies.

Usage

Basic Encryption (CBC Mode)

import os
from xtea_cython import encrypt_cbc, decrypt_cbc

key = os.urandom(16)  # 128-bit key
iv = os.urandom(8)    # 64-bit IV

plaintext = b"Hello, World!"

# Encrypt (with automatic padding)
ciphertext = encrypt_cbc(plaintext, key, iv, auto_pad=True)

# Decrypt
decrypted = decrypt_cbc(ciphertext, key, iv, auto_unpad=True)

assert decrypted == plaintext

Without Padding (PyPI xtea Compatible)

from xtea_cython import encrypt_cbc, decrypt_cbc
import xtea

key = b"0123456789abcdef"
iv = b"abcdefgh"
data = b"12345678" * 10  # Must be multiple of 8 bytes

# Both produce identical results
result1 = encrypt_cbc(data, key, iv)
result2 = xtea.new(key, mode=xtea.MODE_CBC, IV=iv).encrypt(data)

assert result1 == result2  # True

Stream Modes (CTR, CFB, OFB) - No Padding Required

from xtea_cython import encrypt_ctr, decrypt_ctr

nonce = os.urandom(8)

ciphertext = encrypt_ctr(plaintext, key, nonce)
decrypted = decrypt_ctr(ciphertext, key, nonce)

assert decrypted == plaintext

Raw Block Encryption

from xtea_cython import encrypt_block, decrypt_block

block = b"12345678"  # Exactly 8 bytes
key = b"0123456789abcdef"  # Exactly 16 bytes

encrypted = encrypt_block(block, key)
decrypted = decrypt_block(encrypted, key)

Manual Padding Control

from xtea_cython import encrypt_cbc, decrypt_cbc, pkcs7_pad, pkcs7_unpad

# Pad manually
padded = pkcs7_pad(plaintext)
ciphertext = encrypt_cbc(padded, key, iv)

# Unpad manually
decrypted_padded = decrypt_cbc(ciphertext, key, iv)
decrypted = pkcs7_unpad(decrypted_padded)

ECB Mode

from xtea_cython import encrypt_ecb, decrypt_ecb

ciphertext = encrypt_ecb(plaintext, key, auto_pad=True)
decrypted = decrypt_ecb(ciphertext, key, auto_unpad=True)

⚠️ Warning: ECB mode is not secure for most use cases. Same plaintext blocks produce same ciphertext blocks. Use CBC or CTR instead.

Helper Functions

from xtea_cython import generate_key, generate_iv, pkcs7_pad, pkcs7_unpad

key = generate_key()  # 16-byte random key
iv = generate_iv()    # 8-byte random IV

padded = pkcs7_pad(data)
unpadded = pkcs7_unpad(padded)

Custom Rounds

# Default: 64 Feistel rounds (32 cycles)
ciphertext = encrypt_cbc(plaintext, key, iv, auto_pad=True)

# Faster but less secure
ciphertext = encrypt_cbc(plaintext, key, iv, rounds=32, auto_pad=True)

# More secure
ciphertext = encrypt_cbc(plaintext, key, iv, rounds=128, auto_pad=True)

Performance

Benchmarks vs PyPI xtea library:

Operation	xtea_cython	PyPI xtea	Speedup
Raw block	73.2M ops/s	1.0M ops/s	73x
ECB 64B	2.1M ops/s	57K ops/s	37x
CBC 64B	1.8M ops/s	127K ops/s	14x
CTR 1KB	1.2M ops/s	110K ops/s	11x
CFB 1KB	1.3M ops/s	95K ops/s	14x
OFB 1KB	1.3M ops/s	92K ops/s	14x

Run benchmarks:

pip install xtea
python benchmarks.py

Development

git clone https://github.com/somjik-api/xtea_cython.git
cd xtea_cython
python -m venv .venv
source .venv/bin/activate
pip install -e ".[dev]"
pytest tests/ -v

Contributing

1. Fork the repository
2. Create a feature branch
3. Make changes and add tests
4. Run pytest tests/
5. Submit a pull request

License

MIT License - see LICENSE for details.