summaryrefslogtreecommitdiff
path: root/libtommath/bn_mp_dr_reduce.c
diff options
context:
space:
mode:
authorSteffen Jaeckel <s_jaeckel@gmx.de>2019-09-16 15:50:38 +0200
committerSteffen Jaeckel <s_jaeckel@gmx.de>2019-09-16 15:50:38 +0200
commit577b7c01fef2c4dd6ec499398e64aa2adeda7e8f (patch)
tree8d6f745fddd3a9c170f7c98603518f77b515da4f /libtommath/bn_mp_dr_reduce.c
parent663fc015dbb5b39ac6be6630a003f0530af734fb (diff)
downloaddropbear-577b7c01fef2c4dd6ec499398e64aa2adeda7e8f.tar.gz
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
Diffstat (limited to 'libtommath/bn_mp_dr_reduce.c')
-rw-r--r--libtommath/bn_mp_dr_reduce.c100
1 files changed, 48 insertions, 52 deletions
diff --git a/libtommath/bn_mp_dr_reduce.c b/libtommath/bn_mp_dr_reduce.c
index c85ee77..77de433 100644
--- a/libtommath/bn_mp_dr_reduce.c
+++ b/libtommath/bn_mp_dr_reduce.c
@@ -1,4 +1,4 @@
-#include <tommath_private.h>
+#include "tommath_private.h"
#ifdef BN_MP_DR_REDUCE_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
@@ -9,10 +9,7 @@
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
- * The library is free for all purposes without any express
- * guarantee it works.
- *
- * Tom St Denis, tstdenis82@gmail.com, http://libtom.org
+ * SPDX-License-Identifier: Unlicense
*/
/* reduce "x" in place modulo "n" using the Diminished Radix algorithm.
@@ -29,68 +26,67 @@
*
* Input x must be in the range 0 <= x <= (n-1)**2
*/
-int
-mp_dr_reduce (mp_int * x, mp_int * n, mp_digit k)
+int mp_dr_reduce(mp_int *x, const mp_int *n, mp_digit k)
{
- int err, i, m;
- mp_word r;
- mp_digit mu, *tmpx1, *tmpx2;
+ int err, i, m;
+ mp_word r;
+ mp_digit mu, *tmpx1, *tmpx2;
- /* m = digits in modulus */
- m = n->used;
+ /* m = digits in modulus */
+ m = n->used;
- /* ensure that "x" has at least 2m digits */
- if (x->alloc < (m + m)) {
- if ((err = mp_grow (x, m + m)) != MP_OKAY) {
- return err;
- }
- }
+ /* ensure that "x" has at least 2m digits */
+ if (x->alloc < (m + m)) {
+ if ((err = mp_grow(x, m + m)) != MP_OKAY) {
+ return err;
+ }
+ }
-/* top of loop, this is where the code resumes if
- * another reduction pass is required.
- */
+ /* top of loop, this is where the code resumes if
+ * another reduction pass is required.
+ */
top:
- /* aliases for digits */
- /* alias for lower half of x */
- tmpx1 = x->dp;
+ /* aliases for digits */
+ /* alias for lower half of x */
+ tmpx1 = x->dp;
- /* alias for upper half of x, or x/B**m */
- tmpx2 = x->dp + m;
+ /* alias for upper half of x, or x/B**m */
+ tmpx2 = x->dp + m;
- /* set carry to zero */
- mu = 0;
+ /* set carry to zero */
+ mu = 0;
- /* compute (x mod B**m) + k * [x/B**m] inline and inplace */
- for (i = 0; i < m; i++) {
- r = (((mp_word)*tmpx2++) * (mp_word)k) + *tmpx1 + mu;
+ /* compute (x mod B**m) + k * [x/B**m] inline and inplace */
+ for (i = 0; i < m; i++) {
+ r = ((mp_word)*tmpx2++ * (mp_word)k) + *tmpx1 + mu;
*tmpx1++ = (mp_digit)(r & MP_MASK);
mu = (mp_digit)(r >> ((mp_word)DIGIT_BIT));
- }
+ }
- /* set final carry */
- *tmpx1++ = mu;
+ /* set final carry */
+ *tmpx1++ = mu;
- /* zero words above m */
- for (i = m + 1; i < x->used; i++) {
+ /* zero words above m */
+ for (i = m + 1; i < x->used; i++) {
*tmpx1++ = 0;
- }
+ }
- /* clamp, sub and return */
- mp_clamp (x);
+ /* clamp, sub and return */
+ mp_clamp(x);
- /* if x >= n then subtract and reduce again
- * Each successive "recursion" makes the input smaller and smaller.
- */
- if (mp_cmp_mag (x, n) != MP_LT) {
- if ((err = s_mp_sub(x, n, x)) != MP_OKAY) {
- return err;
- }
- goto top;
- }
- return MP_OKAY;
+ /* if x >= n then subtract and reduce again
+ * Each successive "recursion" makes the input smaller and smaller.
+ */
+ if (mp_cmp_mag(x, n) != MP_LT) {
+ if ((err = s_mp_sub(x, n, x)) != MP_OKAY) {
+ return err;
+ }
+ goto top;
+ }
+ return MP_OKAY;
}
#endif
-/* ref: $Format:%D$ */
-/* git commit: $Format:%H$ */
-/* commit time: $Format:%ai$ */
+/* ref: HEAD -> master, tag: v1.1.0 */
+/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */