tests/wycheproof/test_x448.py

# 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.hazmat.primitives.asymmetric.x448 import (
    X448PrivateKey,
    X448PublicKey,
)


@pytest.mark.supported(
    only_if=lambda backend: backend.x448_supported(),
    skip_message="Requires OpenSSL with X448 support",
)
@pytest.mark.wycheproof_tests("x448_test.json")
def test_x448(backend, wycheproof):
    assert set(wycheproof.testgroup.items()) == {
        ("curve", "curve448"),
        ("type", "XdhComp"),
    }

    private_key = X448PrivateKey.from_private_bytes(
        binascii.unhexlify(wycheproof.testcase["private"])
    )
    public_key_bytes = binascii.unhexlify(wycheproof.testcase["public"])
    if len(public_key_bytes) == 57:
        assert wycheproof.acceptable
        assert wycheproof.has_flag("NonCanonicalPublic")
        with pytest.raises(ValueError):
            X448PublicKey.from_public_bytes(public_key_bytes)
        return

    public_key = X448PublicKey.from_public_bytes(public_key_bytes)

    assert wycheproof.valid or wycheproof.acceptable

    expected = binascii.unhexlify(wycheproof.testcase["shared"])
    if expected == b"\x00" * 56:
        assert wycheproof.acceptable
        # OpenSSL returns an error on all zeros shared key
        with pytest.raises(ValueError):
            private_key.exchange(public_key)
    else:
        assert private_key.exchange(public_key) == expected