Mercurial > dropbear
comparison libtommath/bn_mp_montgomery_calc_normalization.c @ 1655:f52919ffd3b1
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> |
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date | Mon, 16 Sep 2019 15:50:38 +0200 |
parents | 8bba51a55704 |
children | 1051e4eea25a |
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1654:cc0fc5131c5c | 1655:f52919ffd3b1 |
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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 */ |