diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index cb5afe3..6c7462c 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -25,6 +25,7 @@
     OpenSSL API wrapper.
     """
     _modules = [
+        "bignum",
         "evp",
         "opensslv",
     ]
diff --git a/cryptography/bindings/openssl/bignum.py b/cryptography/bindings/openssl/bignum.py
new file mode 100644
index 0000000..72d467c
--- /dev/null
+++ b/cryptography/bindings/openssl/bignum.py
@@ -0,0 +1,34 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+INCLUDES = """
+#include <openssl/bn.h>
+"""
+
+TYPES = """
+typedef ... BIGNUM;
+typedef ... BN_ULONG;
+"""
+
+FUNCTIONS = """
+BIGNUM *BN_new();
+void BN_free(BIGNUM *);
+
+int BN_set_word(BIGNUM *, BN_ULONG);
+
+char *BN_bn2hex(const BIGNUM *);
+int BN_hex2bn(BIGNUM **, const char *);
+"""
+
+MACROS = """
+"""