Donatien Garnier
A super trimmed down TLS stack, GPL licensed
Dependents: MiniTLS-HTTPS-Example
MiniTLS - A super trimmed down TLS/SSL Library for embedded devices Author: Donatien Garnier Copyright (C) 2013-2014 AppNearMe Ltd
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
math/mont/fp_montgomery_calc_normalization.c@0:35aa5be3b78d, 2014-06-06 (annotated)
- Committer:
- MiniTLS
- Date:
- Fri Jun 06 10:49:02 2014 +0000
- Revision:
- 0:35aa5be3b78d
Initial commit
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| MiniTLS | 0:35aa5be3b78d | 1 | /* TomsFastMath, a fast ISO C bignum library. |
| MiniTLS | 0:35aa5be3b78d | 2 | * |
| MiniTLS | 0:35aa5be3b78d | 3 | * This project is meant to fill in where LibTomMath |
| MiniTLS | 0:35aa5be3b78d | 4 | * falls short. That is speed ;-) |
| MiniTLS | 0:35aa5be3b78d | 5 | * |
| MiniTLS | 0:35aa5be3b78d | 6 | * This project is public domain and free for all purposes. |
| MiniTLS | 0:35aa5be3b78d | 7 | * |
| MiniTLS | 0:35aa5be3b78d | 8 | * Tom St Denis, tomstdenis@gmail.com |
| MiniTLS | 0:35aa5be3b78d | 9 | */ |
| MiniTLS | 0:35aa5be3b78d | 10 | #include <tfm.h> |
| MiniTLS | 0:35aa5be3b78d | 11 | |
| MiniTLS | 0:35aa5be3b78d | 12 | /* computes a = B**n mod b without division or multiplication useful for |
| MiniTLS | 0:35aa5be3b78d | 13 | * normalizing numbers in a Montgomery system. |
| MiniTLS | 0:35aa5be3b78d | 14 | */ |
| MiniTLS | 0:35aa5be3b78d | 15 | void fp_montgomery_calc_normalization(fp_int *a, fp_int *b) |
| MiniTLS | 0:35aa5be3b78d | 16 | { |
| MiniTLS | 0:35aa5be3b78d | 17 | int x, bits; |
| MiniTLS | 0:35aa5be3b78d | 18 | |
| MiniTLS | 0:35aa5be3b78d | 19 | /* how many bits of last digit does b use */ |
| MiniTLS | 0:35aa5be3b78d | 20 | bits = fp_count_bits (b) % DIGIT_BIT; |
| MiniTLS | 0:35aa5be3b78d | 21 | if (!bits) bits = DIGIT_BIT; |
| MiniTLS | 0:35aa5be3b78d | 22 | |
| MiniTLS | 0:35aa5be3b78d | 23 | /* compute A = B^(n-1) * 2^(bits-1) */ |
| MiniTLS | 0:35aa5be3b78d | 24 | if (b->used > 1) { |
| MiniTLS | 0:35aa5be3b78d | 25 | fp_2expt (a, (b->used - 1) * DIGIT_BIT + bits - 1); |
| MiniTLS | 0:35aa5be3b78d | 26 | } else { |
| MiniTLS | 0:35aa5be3b78d | 27 | fp_set(a, 1); |
| MiniTLS | 0:35aa5be3b78d | 28 | bits = 1; |
| MiniTLS | 0:35aa5be3b78d | 29 | } |
| MiniTLS | 0:35aa5be3b78d | 30 | |
| MiniTLS | 0:35aa5be3b78d | 31 | /* now compute C = A * B mod b */ |
| MiniTLS | 0:35aa5be3b78d | 32 | for (x = bits - 1; x < (int)DIGIT_BIT; x++) { |
| MiniTLS | 0:35aa5be3b78d | 33 | fp_mul_2 (a, a); |
| MiniTLS | 0:35aa5be3b78d | 34 | if (fp_cmp_mag (a, b) != FP_LT) { |
| MiniTLS | 0:35aa5be3b78d | 35 | s_fp_sub (a, b, a); |
| MiniTLS | 0:35aa5be3b78d | 36 | } |
| MiniTLS | 0:35aa5be3b78d | 37 | } |
| MiniTLS | 0:35aa5be3b78d | 38 | } |
| MiniTLS | 0:35aa5be3b78d | 39 | |
| MiniTLS | 0:35aa5be3b78d | 40 | |
| MiniTLS | 0:35aa5be3b78d | 41 | /* $Source: /cvs/libtom/tomsfastmath/src/mont/fp_montgomery_calc_normalization.c,v $ */ |
| MiniTLS | 0:35aa5be3b78d | 42 | /* $Revision: 1.1 $ */ |
| MiniTLS | 0:35aa5be3b78d | 43 | /* $Date: 2006/12/31 21:25:53 $ */ |
