pyUmbral/tests/unit/test_dem.py

80 lines
2.2 KiB
Python

"""
Copyright (C) 2018 NuCypher
This file is part of pyUmbral.
pyUmbral is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
pyUmbral is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with pyUmbral. If not, see <https://www.gnu.org/licenses/>.
"""
import pytest
import os
from umbral.dem import UmbralDEM, DEM_KEYSIZE, DEM_NONCE_SIZE
from cryptography.exceptions import InvalidTag
def test_encrypt_decrypt():
key = os.urandom(32)
dem = UmbralDEM(key)
plaintext = b'peace at dawn'
ciphertext0 = dem.encrypt(plaintext)
ciphertext1 = dem.encrypt(plaintext)
assert ciphertext0 != plaintext
assert ciphertext1 != plaintext
# Ciphertext should be different even with same plaintext.
assert ciphertext0 != ciphertext1
# Nonce should be different
assert ciphertext0[:DEM_NONCE_SIZE] != ciphertext1[:DEM_NONCE_SIZE]
cleartext0 = dem.decrypt(ciphertext0)
cleartext1 = dem.decrypt(ciphertext1)
assert cleartext0 == plaintext
assert cleartext1 == plaintext
def test_encrypt_decrypt_associated_data():
key = os.urandom(32)
aad = b'secret code 1234'
dem = UmbralDEM(key)
plaintext = b'peace at dawn'
ciphertext0 = dem.encrypt(plaintext, authenticated_data=aad)
ciphertext1 = dem.encrypt(plaintext, authenticated_data=aad)
assert ciphertext0 != plaintext
assert ciphertext1 != plaintext
assert ciphertext0 != ciphertext1
assert ciphertext0[:DEM_NONCE_SIZE] != ciphertext1[:DEM_NONCE_SIZE]
cleartext0 = dem.decrypt(ciphertext0, authenticated_data=aad)
cleartext1 = dem.decrypt(ciphertext1, authenticated_data=aad)
assert cleartext0 == plaintext
assert cleartext1 == plaintext
# Attempt decryption with invalid associated data
with pytest.raises(InvalidTag):
cleartext2 = dem.decrypt(ciphertext0, authenticated_data=b'wrong data')