Add BN_native2bn and BN_bn2nativepad, for native BIGNUM import/export

[openssl.git] / crypto / bn / bn_lib.c

diff --git a/crypto/bn/bn_lib.c b/crypto/bn/bn_lib.c
index 80f910c807793490908cb8abbba286787397c91f..6de17c3b7a9b31788be0bc067f87c690fde156ec 100644 (file)
--- a/crypto/bn/bn_lib.c
+++ b/crypto/bn/bn_lib.c
@@ -1,7 +1,7 @@
 /*
  * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
  *
- * Licensed under the OpenSSL license (the "License").  You may not use
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
@@ -15,7 +15,7 @@
 #include "internal/constant_time_locl.h"
 
 /* This stuff appears to be completely unused, so is deprecated */
-#if OPENSSL_API_COMPAT < 0x00908000L
+#if !OPENSSL_API_0_9_8
 /*-
  * For a 32 bit machine
  * 2 -   4 ==  128
@@ -536,6 +536,24 @@ int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen)
     return tolen;
 }
 
+BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret)
+{
+#ifdef B_ENDIAN
+    return BN_bin2bn(s, len, ret);
+#else
+    return BN_lebin2bn(s, len, ret);
+#endif
+}
+
+int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen)
+{
+#ifdef B_ENDIAN
+    return BN_bn2binpad(a, to, tolen);
+#else
+    return BN_bn2lebinpad(a, to, tolen);
+#endif
+}
+
 int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
 {
     int i;
@@ -695,6 +713,9 @@ int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
     int i;
     BN_ULONG aa, bb;
 
+    if (n == 0)
+        return 0;
+
     aa = a[n - 1];
     bb = b[n - 1];
     if (aa != bb)
@@ -737,26 +758,25 @@ int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
     return bn_cmp_words(a, b, cl);
 }
 
-/*
+/*-
  * Constant-time conditional swap of a and b.
- * a and b are swapped if condition is not 0.  The code assumes that at most one bit of condition is set.
- * nwords is the number of words to swap.  The code assumes that at least nwords are allocated in both a and b,
- * and that no more than nwords are used by either a or b.
- * a and b cannot be the same number
+ * a and b are swapped if condition is not 0.
+ * nwords is the number of words to swap.
+ * Assumes that at least nwords are allocated in both a and b.
+ * Assumes that no more than nwords are used by either a or b.
  */
 void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
 {
     BN_ULONG t;
     int i;
 
+    if (a == b)
+        return;
+
     bn_wcheck_size(a, nwords);
     bn_wcheck_size(b, nwords);
 
-    assert(a != b);
-    assert((condition & (condition - 1)) == 0);
-    assert(sizeof(BN_ULONG) >= sizeof(int));
-
-    condition = ((condition - 1) >> (BN_BITS2 - 1)) - 1;
+    condition = ((~condition & ((condition - 1))) >> (BN_BITS2 - 1)) - 1;
 
     t = (a->top ^ b->top) & condition;
     a->top ^= t;
@@ -794,42 +814,16 @@ void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
     a->flags ^= t;
     b->flags ^= t;
 
-#define BN_CONSTTIME_SWAP(ind) \
-        do { \
-                t = (a->d[ind] ^ b->d[ind]) & condition; \
-                a->d[ind] ^= t; \
-                b->d[ind] ^= t; \
-        } while (0)
-
-    switch (nwords) {
-    default:
-        for (i = 10; i < nwords; i++)
-            BN_CONSTTIME_SWAP(i);
-        /* Fallthrough */
-    case 10:
-        BN_CONSTTIME_SWAP(9);   /* Fallthrough */
-    case 9:
-        BN_CONSTTIME_SWAP(8);   /* Fallthrough */
-    case 8:
-        BN_CONSTTIME_SWAP(7);   /* Fallthrough */
-    case 7:
-        BN_CONSTTIME_SWAP(6);   /* Fallthrough */
-    case 6:
-        BN_CONSTTIME_SWAP(5);   /* Fallthrough */
-    case 5:
-        BN_CONSTTIME_SWAP(4);   /* Fallthrough */
-    case 4:
-        BN_CONSTTIME_SWAP(3);   /* Fallthrough */
-    case 3:
-        BN_CONSTTIME_SWAP(2);   /* Fallthrough */
-    case 2:
-        BN_CONSTTIME_SWAP(1);   /* Fallthrough */
-    case 1:
-        BN_CONSTTIME_SWAP(0);
-    }
-#undef BN_CONSTTIME_SWAP
+    /* conditionally swap the data */
+    for (i = 0; i < nwords; i++) {
+        t = (a->d[i] ^ b->d[i]) & condition;
+        a->d[i] ^= t;
+        b->d[i] ^= t;
+    }
 }
 
+#undef BN_CONSTTIME_SWAP_FLAGS
+
 /* Bits of security, see SP800-57 */
 
 int BN_security_bits(int L, int N)