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annotate libtommath/bn_mp_grow.c @ 817:a625f9e135a4

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Constant time memcmp for the hmac and password crypt
author Matt Johnston <matt@ucc.asn.au>
date Thu, 03 Oct 2013 22:25:30 +0800
parents 5ff8218bcee9
children 60fc6476e044
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1 #include <tommath.h>
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2 #ifdef BN_MP_GROW_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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12 * The library is free for all purposes without any express
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13 * guarantee it works.
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14 *
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15 * Tom St Denis, [email protected], http://math.libtomcrypt.com
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16 */
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18 /* grow as required */
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19 int mp_grow (mp_int * a, int size)
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20 {
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21 int i;
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22 mp_digit *tmp;
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24 /* if the alloc size is smaller alloc more ram */
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25 if (a->alloc < size) {
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26 /* ensure there are always at least MP_PREC digits extra on top */
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27 size += (MP_PREC * 2) - (size % MP_PREC);
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29 /* reallocate the array a->dp
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30 *
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31 * We store the return in a temporary variable
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32 * in case the operation failed we don't want
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33 * to overwrite the dp member of a.
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34 */
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35 tmp = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
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36 if (tmp == NULL) {
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37 /* reallocation failed but "a" is still valid [can be freed] */
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38 return MP_MEM;
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39 }
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41 /* reallocation succeeded so set a->dp */
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42 a->dp = tmp;
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44 /* zero excess digits */
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45 i = a->alloc;
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46 a->alloc = size;
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47 for (; i < a->alloc; i++) {
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48 a->dp[i] = 0;
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49 }
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50 }
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51 return MP_OKAY;
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52 }
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53 #endif
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54
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55 /* $Source: /cvs/libtom/libtommath/bn_mp_grow.c,v $ */
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56 /* $Revision: 1.3 $ */
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57 /* $Date: 2006/03/31 14:18:44 $ */