Mercurial > dropbear

annotate libtommath/bn_mp_prime_fermat.c @ 1861:2b3a8026a6ce

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Add re-exec for server This allows ASLR to re-randomize the address space for every connection, preventing some vulnerabilities from being exploitable by repeated probing. Overhead (memory and time) is yet to be confirmed. At present this is only enabled on Linux. Other BSD platforms with fexecve() would probably also work though have not been tested.
author Matt Johnston <matt@ucc.asn.au>
date Sun, 30 Jan 2022 10:14:56 +0800
parents 1051e4eea25a
children
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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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1 #include "tommath_private.h"
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2 #ifdef BN_MP_PRIME_FERMAT_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
1051e4eea25a Update LibTomMath to 1.2.0 (#84)
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4 /* SPDX-License-Identifier: Unlicense */
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6 /* performs one Fermat test.
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7 *
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8 * If "a" were prime then b**a == b (mod a) since the order of
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9 * the multiplicative sub-group would be phi(a) = a-1. That means
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10 * it would be the same as b**(a mod (a-1)) == b**1 == b (mod a).
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11 *
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12 * Sets result to 1 if the congruence holds, or zero otherwise.
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13 */
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14 mp_err mp_prime_fermat(const mp_int *a, const mp_int *b, mp_bool *result)
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15 {
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f52919ffd3b1 update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
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16 mp_int t;
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17 mp_err err;
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18
1655
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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19 /* default to composite */
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20 *result = MP_NO;
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21
1655
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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22 /* ensure b > 1 */
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23 if (mp_cmp_d(b, 1uL) != MP_GT) {
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24 return MP_VAL;
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25 }
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1655
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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27 /* init t */
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28 if ((err = mp_init(&t)) != MP_OKAY) {
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29 return err;
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parents: 1470
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30 }
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parents: 1470
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31
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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32 /* compute t = b**a mod a */
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33 if ((err = mp_exptmod(b, a, a, &t)) != MP_OKAY) {
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34 goto LBL_T;
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35 }
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1655
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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37 /* is it equal to b? */
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38 if (mp_cmp(&t, b) == MP_EQ) {
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39 *result = MP_YES;
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40 }
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41
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parents: 1470
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42 err = MP_OKAY;
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43 LBL_T:
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44 mp_clear(&t);
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45 return err;
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46 }
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47 #endif