[Python] How to do RSA Encryption in Python using PyCryptodome

I am new to the world of encryption and I was wondering if my solution for encrypting/decrypting data is okay.

When creating this, I referenced the API documentation from PyCryptodome: https://pycryptodome.readthedocs.io/en/latest/src/api.html

For reference, I have a client-server application and it is assumed the sender already knows the host's public key.

1. Is it proper to send the session key, nonce, and tag to the host?
2. Is there anything vital that I am missing/overlooked?

def send_data(socket, key, data):
enc_session_key, nonce, tag, ciphertext = encrypt_data(key, data)

encapsulated_data = [enc_session_key, nonce, tag, ciphertext]

data = pickle.dumps(encapsulated_data)

stream = bytes(data)
stream_length = len(stream)
socket.sendall(struct.pack("<Q", stream_length))
socket.sendall(stream)


def encrypt_data(key, data):
recipient_key = key
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)

return enc_session_key, cipher_aes.nonce, tag, ciphertext

def decrypt_data(enc_session_key, nonce, tag, ciphertext):
if not os.path.exists(PRIVATE_PATH):
return None

private_key = RSA.import_key(open(PRIVATE_PATH).read())

# 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)

return data




Here, send_data() is called passing in the socket, public key of the reciever, and the data they would like to send.

It is assumed decrypt_data() is called after a host recieves the data, decrypts it using their private key, and calls pickle.loads() to get the list sent from send_data().

Thank you!!

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