How to use the cryptography.exceptions.UnsupportedAlgorithm function in cryptography

def test_invalid_hash_algorithm(self):
        req = _load_data(
            os.path.join("x509", "ocsp", "req-invalid-hash-alg.der"),
            ocsp.load_der_ocsp_request,
        )
        with pytest.raises(UnsupportedAlgorithm):
            req.hash_algorithm

def test_unsupported_backend(self):
        work_factor = 1024
        block_size = 8
        parallelization_factor = 16
        length = 64
        salt = b"NaCl"
        backend = object()

        with pytest.raises(UnsupportedAlgorithm):
            Scrypt(salt, length, work_factor, block_size,
                   parallelization_factor, backend)

try:
            return self.private_key.decrypt(
                payload,
                # OAEP (Optimal Asymmetric Encryption Padding) is a padding
                # scheme defined in RFC 3447. It provides probabilistic
                # encryption and is proven secure against several attack
                # types. This is the recommended padding algorithm for RSA
                # encryption.
                padding.OAEP(
                    mgf=padding.MGF1(algorithm=_mgf1()),
                    algorithm=_alg(),
                    label=None
                )
            )

        except UnsupportedAlgorithm as e:
            # Decryption Failed
            logger.error(
                'Cryptography / decryption failed '
                '(size=%d, alg=%s, mgf1=%s)' % (
                    len(payload), alg, mgf1,
                )
            )
            logger.debug(
                'Cryptography / Unsupported Algorithm: %s' % (
                    str(e),
                )
            )

        except TypeError:
            # Decryption Failed
            logger.error(

dsa_cdata = self._lib.EVP_PKEY_get1_DSA(evp_pkey)
            self.openssl_assert(dsa_cdata != self._ffi.NULL)
            dsa_cdata = self._ffi.gc(dsa_cdata, self._lib.DSA_free)
            return _DSAPublicKey(self, dsa_cdata, evp_pkey)
        elif key_type == self._lib.EVP_PKEY_EC:
            ec_cdata = self._lib.EVP_PKEY_get1_EC_KEY(evp_pkey)
            self.openssl_assert(ec_cdata != self._ffi.NULL)
            ec_cdata = self._ffi.gc(ec_cdata, self._lib.EC_KEY_free)
            return _EllipticCurvePublicKey(self, ec_cdata, evp_pkey)
        elif key_type in self._dh_types:
            dh_cdata = self._lib.EVP_PKEY_get1_DH(evp_pkey)
            self.openssl_assert(dh_cdata != self._ffi.NULL)
            dh_cdata = self._ffi.gc(dh_cdata, self._lib.DH_free)
            return _DHPublicKey(self, dh_cdata, evp_pkey)
        else:
            raise UnsupportedAlgorithm("Unsupported key type.")

def generate(cls):
        from cryptography.hazmat.backends.openssl.backend import backend
        if not backend.x25519_supported():
            raise UnsupportedAlgorithm(
                "X25519 is not supported by this version of OpenSSL.",
                _Reasons.UNSUPPORTED_EXCHANGE_ALGORITHM
            )
        return backend.x25519_generate_key()

def __init__(self, backend, key, algorithm, ctx=None):
        self._algorithm = algorithm
        self._backend = backend

        if ctx is None:
            ctx = self._backend._lib.Cryptography_HMAC_CTX_new()
            self._backend.openssl_assert(ctx != self._backend._ffi.NULL)
            ctx = self._backend._ffi.gc(
                ctx, self._backend._lib.Cryptography_HMAC_CTX_free
            )
            name = self._backend._build_openssl_digest_name(algorithm)
            evp_md = self._backend._lib.EVP_get_digestbyname(name)
            if evp_md == self._backend._ffi.NULL:
                raise UnsupportedAlgorithm(
                    "{0} is not a supported hash on this backend".format(name),
                    _Reasons.UNSUPPORTED_HASH
                )
            res = self._backend._lib.HMAC_Init_ex(
                ctx, key, len(key), evp_md, self._backend._ffi.NULL
            )
            self._backend.openssl_assert(res != 0)

        self._ctx = ctx
        self._key = key

def _check_signature_algorithm(signature_algorithm):
    if not isinstance(signature_algorithm, ec.ECDSA):
        raise UnsupportedAlgorithm(
            "Unsupported elliptic curve signature algorithm.",
            _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)

raise ValueError("Bad decrypt. Incorrect password?")

        elif errors[0][1:] in (
            (
                self._lib.ERR_LIB_PEM,
                self._lib.PEM_F_PEM_GET_EVP_CIPHER_INFO,
                self._lib.PEM_R_UNSUPPORTED_ENCRYPTION
            ),

            (
                self._lib.ERR_LIB_EVP,
                self._lib.EVP_F_EVP_PBE_CIPHERINIT,
                self._lib.EVP_R_UNKNOWN_PBE_ALGORITHM
            )
        ):
            raise UnsupportedAlgorithm(
                "PEM data is encrypted with an unsupported cipher",
                _Reasons.UNSUPPORTED_CIPHER
            )

        elif any(
            error[1:] == (
                self._lib.ERR_LIB_EVP,
                self._lib.EVP_F_EVP_PKCS82PKEY,
                self._lib.EVP_R_UNSUPPORTED_PRIVATE_KEY_ALGORITHM
            )
            for error in errors
        ):
            raise UnsupportedAlgorithm(
                "Unsupported public key algorithm.",
                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM
            )

def _hash_algorithm(backend, cert_id):
    asn1obj = backend._ffi.new("ASN1_OBJECT **")
    res = backend._lib.OCSP_id_get0_info(
        backend._ffi.NULL, asn1obj,
        backend._ffi.NULL, backend._ffi.NULL, cert_id
    )
    backend.openssl_assert(res == 1)
    backend.openssl_assert(asn1obj[0] != backend._ffi.NULL)
    oid = _obj2txt(backend, asn1obj[0])
    try:
        return _OIDS_TO_HASH[oid]
    except KeyError:
        raise UnsupportedAlgorithm(
            "Signature algorithm OID: {} not recognized".format(oid)
        )

dh_cdata = self._ffi.gc(dh_cdata, self._lib.DH_free)
            return _DHPublicKey(self, dh_cdata, evp_pkey)
        elif key_type == getattr(self._lib, "EVP_PKEY_ED25519", None):
            # EVP_PKEY_ED25519 is not present in OpenSSL < 1.1.1
            return _Ed25519PublicKey(self, evp_pkey)
        elif key_type == getattr(self._lib, "EVP_PKEY_X448", None):
            # EVP_PKEY_X448 is not present in OpenSSL < 1.1.1
            return _X448PublicKey(self, evp_pkey)
        elif key_type == getattr(self._lib, "EVP_PKEY_X25519", None):
            # EVP_PKEY_X25519 is not present in OpenSSL < 1.1.0
            return _X25519PublicKey(self, evp_pkey)
        elif key_type == getattr(self._lib, "EVP_PKEY_ED448", None):
            # EVP_PKEY_X25519 is not present in OpenSSL < 1.1.1
            return _Ed448PublicKey(self, evp_pkey)
        else:
            raise UnsupportedAlgorithm("Unsupported key type.")