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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
import binascii
import pytest
from cryptography.exceptions import InvalidTag
from cryptography.hazmat.backends.interfaces import CipherBackend
from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
from ..hazmat.primitives.test_aead import _aead_supported
@pytest.mark.skipif(
not _aead_supported(ChaCha20Poly1305),
reason="Requires OpenSSL with ChaCha20Poly1305 support"
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
@pytest.mark.wycheproof_tests("chacha20_poly1305_test.json")
def test_chacha2poly1305(wycheproof):
key = binascii.unhexlify(wycheproof.testcase["key"])
iv = binascii.unhexlify(wycheproof.testcase["iv"])
aad = binascii.unhexlify(wycheproof.testcase["aad"])
msg = binascii.unhexlify(wycheproof.testcase["msg"])
ct = binascii.unhexlify(wycheproof.testcase["ct"])
tag = binascii.unhexlify(wycheproof.testcase["tag"])
if wycheproof.valid:
chacha = ChaCha20Poly1305(key)
computed_ct = chacha.encrypt(iv, msg, aad)
assert computed_ct == ct + tag
computed_msg = chacha.decrypt(iv, ct + tag, aad)
assert computed_msg == msg
elif len(iv) != 12:
chacha = ChaCha20Poly1305(key)
with pytest.raises(ValueError):
chacha.encrypt(iv, msg, aad)
with pytest.raises(ValueError):
chacha.decrypt(iv, ct + tag, aad)
else:
chacha = ChaCha20Poly1305(key)
with pytest.raises(InvalidTag):
chacha.decrypt(iv, msg + tag, aad)
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