Simple pure-python chacha20-poly1305 implementation based on tlslite-ng code. Designed to be compatible with Cryptography API.
import os
from chacha20poly1305 import ChaCha20Poly1305
key = os.urandom(32)
cip = ChaCha20Poly1305(key)
nonce = os.urandom(12)
ciphertext = cip.encrypt(nonce, b'test')
plaintext = cip.decrypt(nonce, ciphertext)
print(plaintext)
pip install chacha20poly1305
Please note the pure python implementation probably suffers form side-channels leakage (timing, memory access). For constant time implementations use compiled versions: