Mercurial > dropbear

annotate libtommath/bn_mp_reduce_2k.c @ 1684:d5d25ce2a2ed

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cast to fix warning
author Matt Johnston <matt@ucc.asn.au>
date Tue, 26 May 2020 19:57:28 +0800
parents f52919ffd3b1
children 1051e4eea25a
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
Steffen Jaeckel <s_jaeckel@gmx.de>
parents: 1470
diff changeset
1 #include "tommath_private.h"
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2 #ifdef BN_MP_REDUCE_2K_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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4 *
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5 * LibTomMath is a library that provides multiple-precision
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6 * integer arithmetic as well as number theoretic functionality.
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7 *
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8 * The library was designed directly after the MPI library by
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9 * Michael Fromberger but has been written from scratch with
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10 * additional optimizations in place.
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11 *
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Steffen Jaeckel <s_jaeckel@gmx.de>
parents: 1470
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12 * SPDX-License-Identifier: Unlicense
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13 */
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14
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15 /* reduces a modulo n where n is of the form 2**p - d */
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f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
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parents: 1470
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16 int mp_reduce_2k(mp_int *a, const mp_int *n, mp_digit d)
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17 {
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18 mp_int q;
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19 int p, res;
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20
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21 if ((res = mp_init(&q)) != MP_OKAY) {
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22 return res;
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23 }
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24
60fc6476e044 Update to libtommath v1.0
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25 p = mp_count_bits(n);
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26 top:
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27 /* q = a/2**p, a = a mod 2**p */
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28 if ((res = mp_div_2d(a, p, &q, a)) != MP_OKAY) {
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f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
Steffen Jaeckel <s_jaeckel@gmx.de>
parents: 1470
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29 goto LBL_ERR;
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30 }
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31
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parents: 1470
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32 if (d != 1u) {
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33 /* q = q * d */
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34 if ((res = mp_mul_d(&q, d, &q)) != MP_OKAY) {
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f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
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35 goto LBL_ERR;
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36 }
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37 }
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38
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39 /* a = a + q */
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40 if ((res = s_mp_add(a, &q, a)) != MP_OKAY) {
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parents: 1470
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41 goto LBL_ERR;
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42 }
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43
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44 if (mp_cmp_mag(a, n) != MP_LT) {
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45 if ((res = s_mp_sub(a, n, a)) != MP_OKAY) {
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46 goto LBL_ERR;
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47 }
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48 goto top;
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49 }
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50
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51 LBL_ERR:
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52 mp_clear(&q);
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53 return res;
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54 }
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56 #endif
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57
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58 /* ref: HEAD -> master, tag: v1.1.0 */
f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
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59 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
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parents: 1470
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60 /* commit time: 2019-01-28 20:32:32 +0100 */