Mercurial > dropbear

annotate libtomcrypt/src/pk/dh/dh_check_pubkey.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 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 */
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9
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10 #include "tomcrypt.h"
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11
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12 #ifdef LTC_MDH
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13
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14 /**
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15 Check DH public key (INTERNAL ONLY, not part of public API)
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16 @param key The key you wish to test
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17 @return CRYPT_OK if successful
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18 */
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19 int dh_check_pubkey(dh_key *key)
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20 {
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21 void *p_minus1;
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22 ltc_mp_digit digit;
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23 int i, digit_count, bits_set = 0, err;
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24
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25 LTC_ARGCHK(key != NULL);
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26
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27 if ((err = mp_init(&p_minus1)) != CRYPT_OK) {
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28 return err;
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29 }
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30
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31 /* avoid: y <= 1 OR y >= p-1 */
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32 if ((err = mp_sub_d(key->prime, 1, p_minus1)) != CRYPT_OK) {
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33 goto error;
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34 }
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35 if (mp_cmp(key->y, p_minus1) != LTC_MP_LT || mp_cmp_d(key->y, 1) != LTC_MP_GT) {
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36 err = CRYPT_INVALID_ARG;
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37 goto error;
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38 }
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39
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40 /* public key must have more than one bit set */
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41 digit_count = mp_get_digit_count(key->y);
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42 for (i = 0; i < digit_count && bits_set < 2; i++) {
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43 digit = mp_get_digit(key->y, i);
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44 while (digit > 0) {
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45 if (digit & 1) bits_set++;
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46 digit >>= 1;
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47 }
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48 }
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49 if (bits_set > 1) {
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50 err = CRYPT_OK;
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51 }
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52 else {
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53 err = CRYPT_INVALID_ARG;
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54 }
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55
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56 error:
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57 mp_clear(p_minus1);
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58 return err;
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59 }
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60
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61 #endif /* LTC_MDH */
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62
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63 /* ref: $Format:%D$ */
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64 /* git commit: $Format:%H$ */
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65 /* commit time: $Format:%ai$ */