Mercurial > dropbear

annotate libtommath/bn_mp_to_radix.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
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1692
1051e4eea25a Update LibTomMath to 1.2.0 (#84)
Steffen Jaeckel <s@jaeckel.eu>
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1 #include "tommath_private.h"
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2 #ifdef BN_MP_TO_RADIX_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
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4 /* SPDX-License-Identifier: Unlicense */
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5
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6 /* stores a bignum as a ASCII string in a given radix (2..64)
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7 *
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8 * Stores upto "size - 1" chars and always a NULL byte, puts the number of characters
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9 * written, including the '\0', in "written".
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10 */
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11 mp_err mp_to_radix(const mp_int *a, char *str, size_t maxlen, size_t *written, int radix)
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12 {
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13 size_t digs;
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14 mp_err err;
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15 mp_int t;
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16 mp_digit d;
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17 char *_s = str;
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18
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19 /* check range of radix and size*/
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20 if (maxlen < 2u) {
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21 return MP_BUF;
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22 }
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23 if ((radix < 2) || (radix > 64)) {
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24 return MP_VAL;
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25 }
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26
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27 /* quick out if its zero */
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28 if (MP_IS_ZERO(a)) {
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29 *str++ = '0';
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30 *str = '\0';
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31 if (written != NULL) {
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32 *written = 2u;
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33 }
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34 return MP_OKAY;
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35 }
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36
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37 if ((err = mp_init_copy(&t, a)) != MP_OKAY) {
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38 return err;
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39 }
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40
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41 /* if it is negative output a - */
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42 if (t.sign == MP_NEG) {
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43 /* we have to reverse our digits later... but not the - sign!! */
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44 ++_s;
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45
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46 /* store the flag and mark the number as positive */
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47 *str++ = '-';
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48 t.sign = MP_ZPOS;
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49
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50 /* subtract a char */
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51 --maxlen;
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52 }
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53 digs = 0u;
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54 while (!MP_IS_ZERO(&t)) {
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55 if (--maxlen < 1u) {
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56 /* no more room */
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57 err = MP_BUF;
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58 goto LBL_ERR;
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59 }
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60 if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
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61 goto LBL_ERR;
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62 }
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63 *str++ = mp_s_rmap[d];
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64 ++digs;
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65 }
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66 /* reverse the digits of the string. In this case _s points
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67 * to the first digit [exluding the sign] of the number
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68 */
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69 s_mp_reverse((unsigned char *)_s, digs);
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70
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71 /* append a NULL so the string is properly terminated */
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72 *str = '\0';
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73 digs++;
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74
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75 if (written != NULL) {
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76 *written = (a->sign == MP_NEG) ? (digs + 1u): digs;
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77 }
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78
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79 LBL_ERR:
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80 mp_clear(&t);
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81 return err;
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82 }
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83
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84 #endif