How to use the cryptography.hazmat.primitives.hashes function in cryptography

)


@pytest.mark.supported(
    only_if=lambda backend: backend.hash_supported(hashes.MD5()),
    skip_message="Does not support MD5",
)
@pytest.mark.requires_backend_interface(interface=HashBackend)
class TestMD5(object):
    test_md5 = generate_hash_test(
        load_hash_vectors,
        os.path.join("hashes", "MD5"),
        [
            "rfc-1321.txt",
        ],
        hashes.MD5(),
    )


@pytest.mark.supported(
    only_if=lambda backend: backend.hash_supported(
        hashes.BLAKE2b(digest_size=64)),
    skip_message="Does not support BLAKE2b",
)
@pytest.mark.requires_backend_interface(interface=HashBackend)
class TestBLAKE2b(object):
    test_b2b = generate_hash_test(
        load_hash_vectors,
        os.path.join("hashes", "blake2"),
        [
            "blake2b.txt",
        ],

def test_prehashed_sign(self, backend):
        private_key = RSA_KEY_512.private_key(backend)
        message = b"one little message"
        h = hashes.Hash(hashes.SHA1(), backend)
        h.update(message)
        digest = h.finalize()
        pss = padding.PSS(mgf=padding.MGF1(hashes.SHA1()), salt_length=0)
        prehashed_alg = asym_utils.Prehashed(hashes.SHA1())
        signature = private_key.sign(digest, pss, prehashed_alg)
        public_key = private_key.public_key()
        public_key.verify(signature, message, pss, hashes.SHA1())

    only_if=lambda backend: backend.hmac_supported(hashes.MD5()),
    skip_message="Does not support MD5",

def generate_fingerprint(public_key):
    try:
        pub_bytes = public_key.encode('utf-8')
        # Test that the given public_key string is a proper ssh key. The
        # returned object is unused since pyca/cryptography does not have a
        # fingerprint method.
        serialization.load_ssh_public_key(
            pub_bytes, backends.default_backend())
        pub_data = base64.b64decode(public_key.split(' ')[1])
        digest = hashes.Hash(hashes.MD5(), backends.default_backend())
        digest.update(pub_data)
        md5hash = digest.finalize()
        raw_fp = binascii.hexlify(md5hash)
        if six.PY3:
            raw_fp = raw_fp.decode('ascii')
        return ':'.join(a + b for a, b in zip(raw_fp[::2], raw_fp[1::2]))
    except Exception:
        raise exception.InvalidKeypair(
            reason=_('failed to generate fingerprint'))

def _oaep_hash_supported(self, algorithm):
        if self._lib.Cryptography_HAS_RSA_OAEP_MD:
            return isinstance(
                algorithm, (
                    hashes.SHA1,
                    hashes.SHA224,
                    hashes.SHA256,
                    hashes.SHA384,
                    hashes.SHA512,
                )
            )
        else:
            return isinstance(algorithm, hashes.SHA1)

market_hash = new_order_info[0]
        seller_addr = eth_addr_to_string(new_order_info[3])
        buyer_addr = eth_addr_to_string(new_order_info[2])
        buyer_rsa_public_key = new_order_info[1]
        proxy_id = eth_addr_to_string(new_order_info[4])
        session = get_session()
        raw_aes_key = session.query(FileInfo.aes_key) \
            .filter(FileInfo.market_hash == Encoder.bytes_to_base64_str(market_hash)) \
            .all()[0][0]
        logger.debug("start to encrypt aes key with buyer rsa public key")
        logger.debug("raw aes key: %s", raw_aes_key)
        logger.debug("buyer rsa public key: %s", buyer_rsa_public_key)
        encrypted_aes_key = load_der_public_key(buyer_rsa_public_key, backend=default_backend()).encrypt(
            raw_aes_key,
            padding.OAEP(
                mgf=padding.MGF1(algorithm=hashes.SHA256()),
                algorithm=hashes.SHA256(),
                label=None
            )
        )
        logger.debug("encrypted aes key: %s", encrypted_aes_key)
        logger.debug("order info got generated")
        message = Message()
        seller_data = message.seller_data
        message.type = Message.SELLER_DATA
        seller_data.order_id = order_id
        seller_data.order_type = 'stream'
        seller_data.seller_addr = seller_addr
        seller_data.buyer_addr = buyer_addr
        seller_data.market_hash = Encoder.bytes_to_base64_str(market_hash)
        seller_data.AES_key = encrypted_aes_key
        storage = seller_data.storage

builder = builder.issuer_name(ca_cert.subject)
    builder = builder.not_valid_before(datetime.datetime.today() - one_day)
    builder = builder.not_valid_after(datetime.datetime.today() + datetime.timedelta(days=cert_expiration))
    builder = builder.serial_number(x509.random_serial_number())
    builder = builder.public_key(public_key)
    builder = builder.add_extension(
        x509.SubjectAlternativeName(
            [x509.IPAddress(ipaddress.IPv4Address(host))]
        ),
        critical=False
    )
    builder = builder.add_extension(
        x509.BasicConstraints(ca=False, path_length=None), critical=True,
    )
    certificate = builder.sign(
        private_key=ca_key, algorithm=hashes.SHA256(),
        backend=default_backend()
    )
    private_key = private_key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.TraditionalOpenSSL,
            encryption_algorithm=serialization.NoEncryption(),
        )
    certificate = certificate.public_bytes(serialization.Encoding.PEM)
    return private_key, certificate

def fingerprint(self, algorithm):
        h = hashes.Hash(algorithm, self._backend)
        h.update(self.public_bytes(serialization.Encoding.DER))
        return h.finalize()

def Sign(self, data):
        return self.rsa_key.sign(
            data, padding.PKCS1v15(), utils.Prehashed(hashes.SHA1()))

def _oaep_hash_supported(self, algorithm):
        if self._lib.Cryptography_HAS_RSA_OAEP_MD:
            return isinstance(
                algorithm, (
                    hashes.SHA1,
                    hashes.SHA224,
                    hashes.SHA256,
                    hashes.SHA384,
                    hashes.SHA512,
                )
            )
        else:
            return isinstance(algorithm, hashes.SHA1)