Merge ccdc933 into cd46145

pyca · Apr 18, 2018 · 5d7d820 · 5d7d820
2 parents cd46145 + ccdc933
commit 5d7d820
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diff --git a/src/_cffi_src/openssl/bignum.py b/src/_cffi_src/openssl/bignum.py
@@ -10,11 +10,17 @@
 
 TYPES = """
 typedef ... BN_CTX;
+typedef ... BN_MONT_CTX;
 typedef ... BIGNUM;
 typedef int... BN_ULONG;
 """
 
 FUNCTIONS = """
+#define BN_FLG_CONSTTIME ...
+
+void BN_set_flags(BIGNUM *, int);
+int BN_get_flags(const BIGNUM *, int);
+
 BIGNUM *BN_new(void);
 void BN_free(BIGNUM *);
 void BN_clear_free(BIGNUM *);
@@ -29,6 +35,10 @@
 BIGNUM *BN_CTX_get(BN_CTX *);
 void BN_CTX_end(BN_CTX *);
 
+BN_MONT_CTX *BN_MONT_CTX_new(void);
+int BN_MONT_CTX_set(BN_MONT_CTX *, BIGNUM *, BN_CTX *);
+void BN_MONT_CTX_free(BN_MONT_CTX *);
+
 BIGNUM *BN_copy(BIGNUM *, const BIGNUM *);
 BIGNUM *BN_dup(const BIGNUM *);
 
@@ -63,6 +73,10 @@
 int BN_exp(BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
 int BN_mod_exp(BIGNUM *, const BIGNUM *, const BIGNUM *, const BIGNUM *,
                BN_CTX *);
+int BN_mod_exp_mont(BIGNUM *, const BIGNUM *, const BIGNUM *, const BIGNUM *,
+                    BN_CTX *, BN_MONT_CTX *);
+int BN_mod_exp_mont_consttime(BIGNUM *, const BIGNUM *, const BIGNUM *,
+                              const BIGNUM *, BN_CTX *, BN_MONT_CTX *);
 int BN_gcd(BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
 BIGNUM *BN_mod_inverse(BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
 

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