import hmac
import hashlib

import secrets

# Generate and write shared key

shared_secret: bytes = secrets.token_bytes(16)

with open('k', 'wb') as file:
    file.write(shared_secret)

# Take in message and compute hmac
m = input("Message: ").encode()

hmac_object: hmac.HMAC = hmac.new(shared_secret, m, hashlib.sha256)
m_hash = hmac_object.digest()

print(f'HMAC: {m_hash}')

# Write hmac digest and message

with open('mactext', 'wb') as file:
    file.write(m + m_hash)