Mercurial > dropbear

diff libtommath/bn_mp_tc_xor.c @ 1655:f52919ffd3b1

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79) * make key-generation compliant to FIPS 186.4 * fix includes in tommath_class.h * update fuzzcorpus instead of error-out * fixup fuzzing make-targets * update Makefile.in * apply necessary patches to ltm sources * clean-up not required ltm files * update to vanilla ltm 1.1.0 this already only contains the required files * remove set/get double
author Steffen Jaeckel <s_jaeckel@gmx.de>
date Mon, 16 Sep 2019 15:50:38 +0200
parents
children
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtommath/bn_mp_tc_xor.c	Mon Sep 16 15:50:38 2019 +0200
@@ -0,0 +1,90 @@
+#include "tommath_private.h"
+#ifdef BN_MP_TC_XOR_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * SPDX-License-Identifier: Unlicense
+ */
+
+/* two complement xor */
+int mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c)
+{
+   int res = MP_OKAY, bits, abits, bbits;
+   int as = mp_isneg(a), bs = mp_isneg(b);
+   mp_int *mx = NULL, _mx, acpy, bcpy;
+
+   if ((as != MP_NO) || (bs != MP_NO)) {
+      abits = mp_count_bits(a);
+      bbits = mp_count_bits(b);
+      bits = MAX(abits, bbits);
+      res = mp_init_set_int(&_mx, 1uL);
+      if (res != MP_OKAY) {
+         goto end;
+      }
+
+      mx = &_mx;
+      res = mp_mul_2d(mx, bits + 1, mx);
+      if (res != MP_OKAY) {
+         goto end;
+      }
+
+      if (as != MP_NO) {
+         res = mp_init(&acpy);
+         if (res != MP_OKAY) {
+            goto end;
+         }
+
+         res = mp_add(mx, a, &acpy);
+         if (res != MP_OKAY) {
+            mp_clear(&acpy);
+            goto end;
+         }
+         a = &acpy;
+      }
+      if (bs != MP_NO) {
+         res = mp_init(&bcpy);
+         if (res != MP_OKAY) {
+            goto end;
+         }
+
+         res = mp_add(mx, b, &bcpy);
+         if (res != MP_OKAY) {
+            mp_clear(&bcpy);
+            goto end;
+         }
+         b = &bcpy;
+      }
+   }
+
+   res = mp_xor(a, b, c);
+
+   if ((as != bs) && (res == MP_OKAY)) {
+      res = mp_sub(c, mx, c);
+   }
+
+end:
+   if (a == &acpy) {
+      mp_clear(&acpy);
+   }
+
+   if (b == &bcpy) {
+      mp_clear(&bcpy);
+   }
+
+   if (mx == &_mx) {
+      mp_clear(mx);
+   }
+
+   return res;
+}
+#endif
+
+/* ref:         HEAD -> master, tag: v1.1.0 */
+/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */