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

# Read Bob's public key
with open("bob_public.pem", "rb") as f:
    public_key = RSA.import_key(f.read())

# Get the message from the command line
message = input("Enter a message: ").encode()

# Create a cipher object using Bob's public key
cipher = PKCS1_OAEP.new(public_key)

# Encrypt the message
ciphertext = cipher.encrypt(message)

# Write the ciphertext
with open("ctext", "wb") as f:
    f.write(ciphertext)