require not_valid_after >= not_valid_before

2 files changed, 33 insertions, 0 deletions

diff --git a/src/cryptography/x509/base.py b/src/cryptography/x509/base.py
index c56ca5ee..49761046 100644
--- a/src/cryptography/x509/base.py
+++ b/src/cryptography/x509/base.py
@@ -436,6 +436,11 @@ class CertificateBuilder(object):
         if time <= _UNIX_EPOCH:
             raise ValueError('The not valid before date must be after the unix'
                              ' epoch (1970 January 1).')
+        if self._not_valid_after is not None and time > self._not_valid_after:
+            raise ValueError(
+                'The not valid before date must be before the not valid after '
+                'date.'
+            )
         return CertificateBuilder(
             self._issuer_name, self._subject_name,
             self._public_key, self._serial_number, time,
@@ -453,6 +458,12 @@ class CertificateBuilder(object):
         if time <= _UNIX_EPOCH:
             raise ValueError('The not valid after date must be after the unix'
                              ' epoch (1970 January 1).')
+        if (self._not_valid_before is not None and
+                time < self._not_valid_before):
+            raise ValueError(
+                'The not valid after date must be after the not valid before '
+                'date.'
+            )
         return CertificateBuilder(
             self._issuer_name, self._subject_name,
             self._public_key, self._serial_number, self._not_valid_before,
diff --git a/tests/test_x509.py b/tests/test_x509.py
index 0a1870d5..86f771b3 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -1437,6 +1437,28 @@ class TestCertificateBuilder(object):
         with pytest.raises(ValueError):
             builder.subject_name(name)
 
+    def test_not_valid_before_after_not_valid_after(self):
+        builder = x509.CertificateBuilder()
+
+        builder = builder.not_valid_after(
+            datetime.datetime(2002, 1, 1, 12, 1)
+        )
+        with pytest.raises(ValueError):
+            builder.not_valid_before(
+                datetime.datetime(2003, 1, 1, 12, 1)
+            )
+
+    def test_not_valid_after_before_not_valid_before(self):
+        builder = x509.CertificateBuilder()
+
+        builder = builder.not_valid_before(
+            datetime.datetime(2002, 1, 1, 12, 1)
+        )
+        with pytest.raises(ValueError):
+            builder.not_valid_after(
+                datetime.datetime(2001, 1, 1, 12, 1)
+            )
+
     @pytest.mark.requires_backend_interface(interface=RSABackend)
     @pytest.mark.requires_backend_interface(interface=X509Backend)
     def test_public_key_must_be_public_key(self, backend):