add a CRL public_bytes method

5 files changed, 76 insertions, 0 deletions

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index cb2934cf..bcad55a3 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,9 @@ Changelog
 * :class:`~cryptography.x509.NameConstraints` are now supported in the
   :class:`~cryptography.x509.CertificateBuilder` and
   :class:`~cryptography.x509.CertificateSigningRequestBuilder`.
+* Support serialization of certificate revocation lists using the
+  ``public_bytes`` method of
+  :class:`~cryptography.x509.CertificateRevocationList`.
 
 1.1.2 - 2015-12-10
 ~~~~~~~~~~~~~~~~~~
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index 91c53444..d0606330 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -523,6 +523,18 @@ X.509 CRL (Certificate Revocation List) Object
         used to validate a signature, but use extreme caution as CRL validation
         is a complex problem that involves much more than just signature checks.
 
+    .. method:: public_bytes(encoding)
+
+        .. versionadded:: 1.2
+
+        :param encoding: The
+            :class:`~cryptography.hazmat.primitives.serialization.Encoding`
+            that will be used to serialize the certificate revocation list.
+
+        :return bytes: The data that can be written to a file or sent
+            over the network and used as part of a certificate verification
+            process.
+
 
 X.509 Certificate Builder
 ~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index f50a0d5d..b7a88a4a 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -833,6 +833,20 @@ class _CertificateRevocationList(object):
         )
         return self._backend._ffi.buffer(pp[0], res)[:]
 
+    def public_bytes(self, encoding):
+        bio = self._backend._create_mem_bio()
+        if encoding is serialization.Encoding.PEM:
+            res = self._backend._lib.PEM_write_bio_X509_CRL(
+                bio, self._x509_crl
+            )
+        elif encoding is serialization.Encoding.DER:
+            res = self._backend._lib.i2d_X509_CRL_bio(bio, self._x509_crl)
+        else:
+            raise TypeError("encoding must be an item from the Encoding enum")
+
+        self._backend.openssl_assert(res == 1)
+        return self._backend._read_mem_bio(bio)
+
     def _revoked_certificates(self):
         revoked = self._backend._lib.X509_CRL_get_REVOKED(self._x509_crl)
         revoked_list = []
diff --git a/src/cryptography/x509/base.py b/src/cryptography/x509/base.py
index 49761046..057d0e9b 100644
--- a/src/cryptography/x509/base.py
+++ b/src/cryptography/x509/base.py
@@ -156,6 +156,11 @@ class Certificate(object):
 
 @six.add_metaclass(abc.ABCMeta)
 class CertificateRevocationList(object):
+    @abc.abstractmethod
+    def public_bytes(self, encoding):
+        """
+        Serializes the CRL to PEM or DER format.
+        """
 
     @abc.abstractmethod
     def fingerprint(self, algorithm):
diff --git a/tests/test_x509.py b/tests/test_x509.py
index 511aac6b..fecafecc 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -222,6 +222,48 @@ class TestCertificateRevocationList(object):
         verifier.update(crl.tbs_certlist_bytes)
         verifier.verify()
 
+    def test_public_bytes_pem(self, backend):
+        crl = _load_cert(
+            os.path.join("x509", "custom", "crl_empty.pem"),
+            x509.load_pem_x509_crl,
+            backend
+        )
+
+        # Encode it to PEM and load it back.
+        crl = x509.load_pem_x509_crl(crl.public_bytes(
+            encoding=serialization.Encoding.PEM,
+        ), backend)
+
+        assert len(crl) == 0
+        assert crl.last_update == datetime.datetime(2015, 12, 20, 23, 44, 47)
+        assert crl.next_update == datetime.datetime(2015, 12, 28, 0, 44, 47)
+
+    def test_public_bytes_der(self, backend):
+        crl = _load_cert(
+            os.path.join("x509", "custom", "crl_all_reasons.pem"),
+            x509.load_pem_x509_crl,
+            backend
+        )
+
+        # Encode it to DER and load it back.
+        crl = x509.load_der_x509_crl(crl.public_bytes(
+            encoding=serialization.Encoding.DER,
+        ), backend)
+
+        assert len(crl) == 12
+        assert crl.last_update == datetime.datetime(2015, 1, 1, 0, 0, 0)
+        assert crl.next_update == datetime.datetime(2016, 1, 1, 0, 0, 0)
+
+    def test_public_bytes_invalid_encoding(self, backend):
+        crl = _load_cert(
+            os.path.join("x509", "custom", "crl_empty.pem"),
+            x509.load_pem_x509_crl,
+            backend
+        )
+
+        with pytest.raises(TypeError):
+            crl.public_bytes('NotAnEncoding')
+
 
 @pytest.mark.requires_backend_interface(interface=X509Backend)
 class TestRevokedCertificate(object):