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comparison libtommath/bn_mp_montgomery_calc_normalization.c @ 1655:f52919ffd3b1

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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 8bba51a55704
children 1051e4eea25a
comparison
equal deleted inserted replaced
1654:cc0fc5131c5c 1655:f52919ffd3b1
1 #include <tommath_private.h> 1 #include "tommath_private.h"
2 #ifdef BN_MP_MONTGOMERY_CALC_NORMALIZATION_C 2 #ifdef BN_MP_MONTGOMERY_CALC_NORMALIZATION_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 * 4 *
5 * LibTomMath is a library that provides multiple-precision 5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality. 6 * integer arithmetic as well as number theoretic functionality.
7 * 7 *
8 * The library was designed directly after the MPI library by 8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with 9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place. 10 * additional optimizations in place.
11 * 11 *
12 * The library is free for all purposes without any express 12 * SPDX-License-Identifier: Unlicense
13 * guarantee it works.
14 *
15 * Tom St Denis, [email protected], http://libtom.org
16 */ 13 */
17 14
18 /* 15 /*
19 * shifts with subtractions when the result is greater than b. 16 * shifts with subtractions when the result is greater than b.
20 * 17 *
21 * The method is slightly modified to shift B unconditionally upto just under 18 * The method is slightly modified to shift B unconditionally upto just under
22 * the leading bit of b. This saves alot of multiple precision shifting. 19 * the leading bit of b. This saves alot of multiple precision shifting.
23 */ 20 */
24 int mp_montgomery_calc_normalization (mp_int * a, mp_int * b) 21 int mp_montgomery_calc_normalization(mp_int *a, const mp_int *b)
25 { 22 {
26 int x, bits, res; 23 int x, bits, res;
27 24
28 /* how many bits of last digit does b use */ 25 /* how many bits of last digit does b use */
29 bits = mp_count_bits (b) % DIGIT_BIT; 26 bits = mp_count_bits(b) % DIGIT_BIT;
30 27
31 if (b->used > 1) { 28 if (b->used > 1) {
32 if ((res = mp_2expt (a, ((b->used - 1) * DIGIT_BIT) + bits - 1)) != MP_OKAY) { 29 if ((res = mp_2expt(a, ((b->used - 1) * DIGIT_BIT) + bits - 1)) != MP_OKAY) {
33 return res; 30 return res;
34 } 31 }
35 } else { 32 } else {
36 mp_set(a, 1); 33 mp_set(a, 1uL);
37 bits = 1; 34 bits = 1;
38 } 35 }
39 36
40 37
41 /* now compute C = A * B mod b */ 38 /* now compute C = A * B mod b */
42 for (x = bits - 1; x < (int)DIGIT_BIT; x++) { 39 for (x = bits - 1; x < (int)DIGIT_BIT; x++) {
43 if ((res = mp_mul_2 (a, a)) != MP_OKAY) { 40 if ((res = mp_mul_2(a, a)) != MP_OKAY) {
44 return res; 41 return res;
45 }
46 if (mp_cmp_mag (a, b) != MP_LT) {
47 if ((res = s_mp_sub (a, b, a)) != MP_OKAY) {
48 return res;
49 } 42 }
50 } 43 if (mp_cmp_mag(a, b) != MP_LT) {
51 } 44 if ((res = s_mp_sub(a, b, a)) != MP_OKAY) {
45 return res;
46 }
47 }
48 }
52 49
53 return MP_OKAY; 50 return MP_OKAY;
54 } 51 }
55 #endif 52 #endif
56 53
57 /* ref: $Format:%D$ */ 54 /* ref: HEAD -> master, tag: v1.1.0 */
58 /* git commit: $Format:%H$ */ 55 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
59 /* commit time: $Format:%ai$ */ 56 /* commit time: 2019-01-28 20:32:32 +0100 */