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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 os
import pytest
from cryptography.exceptions import InvalidTag, _Reasons
from cryptography.hazmat.backends.interfaces import CipherBackend
from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
from ...utils import (
load_nist_vectors, load_vectors_from_file, raises_unsupported_algorithm
)
@pytest.mark.supported(
only_if=lambda backend: (
not backend.aead_cipher_supported(ChaCha20Poly1305)
),
skip_message="Requires OpenSSL without ChaCha20Poly1305 support"
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
def test_chacha20poly1305_unsupported_on_older_openssl(backend):
with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_CIPHER):
ChaCha20Poly1305(ChaCha20Poly1305.generate_key())
@pytest.mark.supported(
only_if=lambda backend: backend.aead_cipher_supported(ChaCha20Poly1305),
skip_message="Does not support ChaCha20Poly1305"
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestChaCha20Poly1305(object):
def test_generate_key(self):
key = ChaCha20Poly1305.generate_key()
assert len(key) == 32
def test_bad_key(self, backend):
with pytest.raises(TypeError):
ChaCha20Poly1305(object())
with pytest.raises(ValueError):
ChaCha20Poly1305(b"0" * 31)
@pytest.mark.parametrize(
("nonce", "data", "associated_data"),
[
[object(), b"data", b""],
[b"0" * 12, object(), b""],
[b"0" * 12, b"data", object()]
]
)
def test_params_not_bytes_encrypt(self, nonce, data, associated_data,
backend):
key = ChaCha20Poly1305.generate_key()
chacha = ChaCha20Poly1305(key)
with pytest.raises(TypeError):
chacha.encrypt(nonce, data, associated_data)
with pytest.raises(TypeError):
chacha.decrypt(nonce, data, associated_data)
def test_nonce_not_12_bytes(self, backend):
key = ChaCha20Poly1305.generate_key()
chacha = ChaCha20Poly1305(key)
with pytest.raises(ValueError):
chacha.encrypt(b"00", b"hello", b"")
with pytest.raises(ValueError):
chacha.decrypt(b"00", b"hello", b"")
def test_decrypt_data_too_short(self, backend):
key = ChaCha20Poly1305.generate_key()
chacha = ChaCha20Poly1305(key)
with pytest.raises(InvalidTag):
chacha.decrypt(b"0" * 12, b"0", None)
def test_associated_data_none_equal_to_empty_bytestring(self, backend):
key = ChaCha20Poly1305.generate_key()
chacha = ChaCha20Poly1305(key)
nonce = os.urandom(12)
ct1 = chacha.encrypt(nonce, b"some_data", None)
ct2 = chacha.encrypt(nonce, b"some_data", b"")
assert ct1 == ct2
pt1 = chacha.decrypt(nonce, ct1, None)
pt2 = chacha.decrypt(nonce, ct2, b"")
assert pt1 == pt2
@pytest.mark.parametrize(
"vector",
load_vectors_from_file(
os.path.join("ciphers", "ChaCha20Poly1305", "openssl.txt"),
load_nist_vectors
)
)
def test_openssl_vectors(self, vector, backend):
key = binascii.unhexlify(vector["key"])
nonce = binascii.unhexlify(vector["iv"])
aad = binascii.unhexlify(vector["aad"])
tag = binascii.unhexlify(vector["tag"])
pt = binascii.unhexlify(vector["plaintext"])
ct = binascii.unhexlify(vector["ciphertext"])
chacha = ChaCha20Poly1305(key)
if vector.get("result") == b"CIPHERFINAL_ERROR":
with pytest.raises(InvalidTag):
chacha.decrypt(nonce, ct + tag, aad)
else:
computed_pt = chacha.decrypt(nonce, ct + tag, aad)
assert computed_pt == pt
computed_ct = chacha.encrypt(nonce, pt, aad)
assert computed_ct == ct + tag
@pytest.mark.parametrize(
"vector",
load_vectors_from_file(
os.path.join("ciphers", "ChaCha20Poly1305", "boringssl.txt"),
load_nist_vectors
)
)
def test_boringssl_vectors(self, vector, backend):
key = binascii.unhexlify(vector["key"])
nonce = binascii.unhexlify(vector["nonce"])
if vector["ad"].startswith(b'"'):
aad = vector["ad"][1:-1]
else:
aad = binascii.unhexlify(vector["ad"])
tag = binascii.unhexlify(vector["tag"])
if vector["in"].startswith(b'"'):
pt = vector["in"][1:-1]
else:
pt = binascii.unhexlify(vector["in"])
ct = binascii.unhexlify(vector["ct"].strip(b'"'))
chacha = ChaCha20Poly1305(key)
computed_pt = chacha.decrypt(nonce, ct + tag, aad)
assert computed_pt == pt
computed_ct = chacha.encrypt(nonce, pt, aad)
assert computed_ct == ct + tag
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