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+.. hazmat::
+
+Key Serialization
+=================
+
+.. currentmodule:: cryptography.hazmat.primitives.serialization
+
+There are several common schemes for serializing asymmetric private and public
+keys to bytes. They generally support encryption of private keys and additional
+key metadata.
+
+Many serialization formats support multiple different types of asymmetric keys
+and will return an an instance of the appropriate type. You should check that
+the returned key matches the type your application expects when using these
+methods.
+
+ .. code-block:: pycon
+
+ >>> key = load_pkcs8_private_key(pem_data, None, backend)
+ >>> if isinstance(key, rsa.RSAPrivateKey):
+ >>> signature = sign_with_rsa_key(key, message)
+ >>> elif isinstance(key, dsa.DSAPrivateKey):
+ >>> signature = sign_with_dsa_key(key, message)
+ >>> else:
+ >>> raise TypeError
+
+
+PKCS #8 Format
+~~~~~~~~~~~~~~
+
+PKCS #8 is a serialization format originally standardized by RSA and
+currently maintained by the IETF in :rfc:`5208`. It supports password based
+encryption and additional key metadata attributes.
+
+
+.. function:: load_pkcs8_private_key(data, password, backend)
+
+ .. versionadded:: 0.5
+
+ Deserialize a private key from PEM encoded data to one of the supported
+ asymmetric private key types.
+
+ :param bytes data: The PEM encoded key data.
+
+ :param bytes password: The password to use to decrypt the data. Should
+ be ``None`` if the private key is not encrypted.
+ :param backend: A
+ :class:`~cryptography.hazmat.backends.interfaces.PKCS8SerializationBackend`
+ provider.
+
+ :returns: A new instance of a private key.
+
+ :raises ValueError: If the PEM data could not be decrypted or if its
+ structure could not be decoded successfully.
+
+ :raises TypeError: If a ``password`` was given and the private key was
+ not encrypted. Or if the key was encrypted but no
+ password was supplied.
+
+ :raises UnsupportedAlgorithm: If the serialized key is of a type that
+ is not supported by the backend or if the key is encrypted with a
+ symmetric cipher that is not supported by the backend.
+
+
+Traditional OpenSSL Format
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The "traditional" PKCS #1 based serialization format used by OpenSSL.
+It supports password based symmetric key encryption. Commonly found in
+OpenSSL based TLS applications. It is usually found in PEM format with a
+header that mentions the type of the serialized key. e.g.
+``-----BEGIN RSA PRIVATE KEY-----``.
+
+.. function:: load_pem_traditional_openssl_private_key(data, password, backend)
+
+ .. versionadded:: 0.5
+
+ Deserialize a private key from PEM encoded data to one of the supported
+ asymmetric private key types.
+
+ :param bytes data: The PEM encoded key data.
+
+ :param bytes password: The password to use to decrypt the data. Should
+ be ``None`` if the private key is not encrypted.
+ :param backend: A
+ :class:`~cryptography.hazmat.backends.interfaces.TraditionalOpenSSLSerializationBackend`
+ provider.
+
+ :returns: A new instance of a private key.
+
+ :raises ValueError: If the PEM data could not be decrypted or if its
+ structure could not be decoded successfully.
+
+ :raises TypeError: If a ``password`` was given and the private key was
+ not encrypted. Or if the key was encrypted but no
+ password was supplied.
+
+ :raises UnsupportedAlgorithm: If the serialized key is of a type that
+ is not supported by the backend or if the key is encrypted with a
+ symmetric cipher that is not supported by the backend.