from Crypto.PublicKey import RSA
from Crypto.Random import get_random_bytes
from Crypto.Cipher import AES, PKCS1_OAEP

class Encrypt:
    def __init__(self):
        self.key = RSA.generate(2048)

    def gen_public_key(self):
        self.public_key = self.key.publickey().export_key()

        file_out = open("receiver.pem", "wb")
        file_out.write(self.public_key)
        file_out.close()


    def gen_private_key(self):
        private_key = self.key.export_key()

        file_out = open("private.pem", "wb")
        file_out.write(private_key)
        file_out.close()


    def encode(self):
        data = "I met aliens in UFO. Here is the map,I met aliens in UFO. Here is the mapI met aliens in UFO. Here is the map,I met aliens in UFO. Here is the mapI met aliens in UFO. Here is the map.".encode("utf-8")
        file_out = open("encrypted_data.bin", "wb")

        recipient_key = RSA.import_key(open("receiver.pem").read())
        session_key = get_random_bytes(16)

        # Encrypt the session key with the public RSA key
        cipher_rsa = PKCS1_OAEP.new(recipient_key)
        enc_session_key = cipher_rsa.encrypt(session_key)

        # Encrypt the data with the AES session key
        cipher_aes = AES.new(session_key, AES.MODE_EAX)
        ciphertext, tag = cipher_aes.encrypt_and_digest(data)
        [ file_out.write(x) for x in (enc_session_key, cipher_aes.nonce, tag, ciphertext) ]
        file_out.close()


    def decode(self):
        file_in = open("encrypted_data.bin", "rb")
        private_key = RSA.import_key(open("private.pem").read())
        enc_session_key, nonce, tag, ciphertext = \
            [file_in.read(x) for x in (private_key.size_in_bytes(), 16, 16, -1)]

        # Decrypt the session key with the private RSA key
        cipher_rsa = PKCS1_OAEP.new(private_key)
        session_key = cipher_rsa.decrypt(enc_session_key)

        # Decrypt the data with the AES session key
        cipher_aes = AES.new(session_key, AES.MODE_EAX, nonce)
        data = cipher_aes.decrypt_and_verify(ciphertext, tag)
        print(data.decode("utf-8"))


if __name__ == "__main__":
    e = Encrypt()

    # e.gen_public_key()
    # e.encode()

    e.gen_private_key()
    e.decode()