Add _tmp_bn_mont_ctx context manager

pyca · Apr 18, 2018 · ccdc933 · ccdc933
1 parent 7d52269
commit ccdc933
Showing 1 changed file with 11 additions and 0 deletions.
diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
@@ -1461,6 +1461,17 @@ def _tmp_bn_ctx(self):
         finally:
             self._lib.BN_CTX_end(bn_ctx)
 
+    @contextmanager
+    def _tmp_bn_mont_ctx(self, modulus):
+        bn_mont_ctx = self._lib.BN_MONT_CTX_new()
+        self.openssl_assert(bn_mont_ctx != self._ffi.NULL)
+        bn_mont_ctx = self._ffi.gc(bn_mont_ctx, self._lib.BN_MONT_CTX_free)
+
+        with self._tmp_bn_ctx() as bn_ctx:
+            res = self._lib.BN_MONT_CTX_set(bn_mont_ctx, modulus, bn_ctx)
+            self.openssl_assert(res == 1)
+        yield bn_mont_ctx
+
     def _ec_key_determine_group_get_func(self, ctx):
         """
         Given an EC_KEY determine the group and what function is required to