Add a bytes method to get the DER ASN.1 encoding of an X509 name. (#3236)

* Add a bytes method to get the DER ASN.1 encoding of an X509 name.

This is useful for creating an OpenSSL style subject_name_hash (#3011)

* add to backend interface and update multibackend

* bytes -> public_bytes

2 files changed, 18 insertions, 0 deletions

diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index 0a0d1456..942a359c 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -585,6 +585,14 @@ A specific ``backend`` may provide one or more of these interfaces.
         :returns: A new instance of
             :class:`~cryptography.x509.RevokedCertificate`.
 
+    .. method:: x509_name_bytes(name)
+
+        .. versionadded:: 1.6
+
+        :param name: An instance of :class:`~cryptography.x509.Name`.
+
+        :return bytes: The DER encoded bytes.
+
 .. class:: DHBackend
 
     .. versionadded:: 0.9
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index bc408ae6..d3e72c0a 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -1142,6 +1142,16 @@ X.509 CSR (Certificate Signing Request) Builder Object
             >>> cert.subject.get_attributes_for_oid(NameOID.COMMON_NAME)
             [<NameAttribute(oid=<ObjectIdentifier(oid=2.5.4.3, name=commonName)>, value=u'Good CA')>]
 
+    .. method:: public_bytes(backend)
+
+        .. versionadded:: 1.6
+
+        :param backend: A backend supporting the
+            :class:`~cryptography.hazmat.backends.interfaces.X509Backend`
+            interface.
+
+        :return bytes: The DER encoded name.
+
 .. class:: Version
 
     .. versionadded:: 0.7