def main():
#Welcome
print("Welcome to CipherText!")
sender = str(input("Who is sending the message? "))
receiver = str(input("Who is receiving the message? "))
#Key Generation to obtain derived key from X25519 + HKDF
derived_key = key_gen.handshake(sender)
#Message Encryption using derived_key as the key to AES GCM
message = str(input("Please type the message you'd like to send: "))
message = (bytes(message, encoding='utf8') if not
isinstance(message, bytes) else message)
#This is just information associated to the user, authenticated with the key but not encrypted.
associated_data = b"This is the user_id, unique to the user from the company server"
# hashing does not work:
# associated_data = hash(derived_key, associated_data)
aesgcm_packet, aesgcm_nonce, ciphertext = aesgcm.encrypt(derived_key, message, associated_data)
print(sender, "sent", ciphertext)
#for demo purposes:
#twilio_sms.send(ciphertext)
#plaintext = twilio_sms.receive(ciphertext)
#twilio_sms.send(plaintext)
#check hash
# associated_data = associated_data.finalize()
plaintext = aesgcm.decrypt(aesgcm_packet, aesgcm_nonce, ciphertext, associated_data)
print(receiver, "got", plaintext, "associated_data:", associated_data)
def main():
#Welcome
print("Welcome to CipherText!")
sender = str(input("Who is sending the message? "))
receiver = str(input("Who is receiving the message? "))
#Key Generation to obtain derived key from X25519 + HKDF
derived_key = key_gen.handshake(sender)
#Message Encryption using derived_key as the key to AES GCM
message = str(input("Please type the message you'd like to send: "))
message = (bytes(message, encoding='utf8') if not
isinstance(message, bytes) else message)
#This is information associated to the user, authenticated with the key but not encrypted.
#According to AESGCM, this associated_data must not be encrypted.
associated_data = b"This could be the user_id, unique to the user from the company server"
#aesgcm.encrypt returns ciphertext bytes with the 16 byte tag appended
aesgcm_packet, aesgcm_nonce, ciphertext = aesgcm.encrypt(derived_key, message, associated_data)
print(sender, "sent", ciphertext)
#aesgcm.decrypt takes the encrypted data with the 16 bit tag appended, and returns the original plaintext.
plaintext = aesgcm.decrypt(aesgcm_packet, aesgcm_nonce, ciphertext, associated_data)
print(receiver, "got", plaintext, "associated_data:", associated_data)
def aes_decrypt(encrypted_txt):
encoded_key = get_key_from_local_state()
encrypted_key = base64.b64decode(encoded_key.encode())
encrypted_key = encrypted_key[5:]
key = dpapi_decrypt(encrypted_key)
nonce = encrypted_txt[3:15]
cipher = aesgcm.get_cipher(key)
return aesgcm.decrypt(cipher, encrypted_txt[15:], nonce)
def aes_decrypt(encrypted_txt):
encoded_key = get_key_from_local_state()
encrypted_key = base64.b64decode(encoded_key.encode())
#remove prefix 'DPAPI'
encrypted_key = encrypted_key[5:]
key = dpapi_decrypt(encrypted_key)
#get nonce. ignore prefix 'v10', length is 12 bytes.
nonce = encrypted_txt[3:15]
cipher = aesgcm.get_cipher(key)
return aesgcm.decrypt(cipher, encrypted_txt[15:], nonce)