tests/hazmat/bindings/test_openssl.py

# Licensed under the Apache License, Version 2.0 (the "License");
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#
#    http://www.apache.org/licenses/LICENSE-2.0
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import binascii

import pytest

from cryptography.exceptions import UnsupportedAlgorithm
from cryptography.hazmat.bindings.openssl.backend import backend, Backend
from cryptography.hazmat.primitives.block import BlockCipher
from cryptography.hazmat.primitives.block.ciphers import AES, TripleDES
from cryptography.hazmat.primitives.block.modes import CBC, ECB


class TestOpenSSL(object):
    def test_backend_exists(self):
        assert backend

    def test_openssl_version_text(self):
        """
        This test checks the value of OPENSSL_VERSION_TEXT.

        Unfortunately, this define does not appear to have a
        formal content definition, so for now we'll test to see
        if it starts with OpenSSL as that appears to be true
        for every OpenSSL.
        """
        assert backend.openssl_version_text().startswith("OpenSSL")

    def test_supports_cipher(self):
        assert backend.ciphers.supported(None, None) is False

    def test_register_duplicate_cipher_adapter(self):
        with pytest.raises(ValueError):
            backend.ciphers.register_cipher_adapter(AES, CBC, None)

    def test_instances_share_ffi(self):
        b = Backend()
        assert b.ffi is backend.ffi
        assert b.lib is backend.lib

    def test_nonexistent_cipher(self):
        b = Backend()
        # TODO: this test assumes that 3DES-ECB doesn't exist
        b.ciphers.register_cipher_adapter(
            TripleDES, ECB, lambda backend, cipher, mode: backend.ffi.NULL
        )
        cipher = BlockCipher(
            TripleDES(binascii.unhexlify(b"0" * 16)), ECB(), backend=b
        )
        with pytest.raises(UnsupportedAlgorithm):
            cipher.encryptor()