from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
import os

# Check if keys already exist
if not os.path.exists("bob_private.pem"):
    key = RSA.generate(2048)

    private_key = key.export_key()
    public_key = key.publickey().export_key()

    # Save the private key
    with open("bob_private.pem", "wb") as f:
        f.write(private_key)

    # Save the public key
    with open("bob_public.pem", "wb") as f:
        f.write(public_key)

    print("Generated and saved Bob's public and private keys.")

if not os.path.exists('ctext'):
    print('No ctext found. Run alice.py')
    exit(0)

# Read the private key
with open("bob_private.pem", "rb") as f:
    private_key = RSA.import_key(f.read())

# Read the ciphertext
with open("ctext", "rb") as f:
    ciphertext = f.read()

print(f'Ciphertext: {ciphertext}')

cipher = PKCS1_OAEP.new(private_key)

# Decrypt
message = cipher.decrypt(ciphertext)
print("Decrypted message:", message.decode())