1 #include <tommath.h> 2 #ifdef BN_MP_RAND_C 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 4 * 5 * LibTomMath is a library that provides multiple-precision 6 * integer arithmetic as well as number theoretic functionality. 7 * 8 * The library was designed directly after the MPI library by 9 * Michael Fromberger but has been written from scratch with 10 * additional optimizations in place. 11 * 12 * The library is free for all purposes without any express 13 * guarantee it works. 14 * 15 * Tom St Denis, tomstdenis (at) gmail.com, http://math.libtomcrypt.com 16 */ 17 18 /* makes a pseudo-random int of a given size */ 19 int 20 mp_rand (mp_int * a, int digits) 21 { 22 int res; 23 mp_digit d; 24 25 mp_zero (a); 26 if (digits <= 0) { 27 return MP_OKAY; 28 } 29 30 /* first place a random non-zero digit */ 31 do { 32 d = ((mp_digit) abs (rand ())) & MP_MASK; 33 } while (d == 0); 34 35 if ((res = mp_add_d (a, d, a)) != MP_OKAY) { 36 return res; 37 } 38 39 while (--digits > 0) { 40 if ((res = mp_lshd (a, 1)) != MP_OKAY) { 41 return res; 42 } 43 44 if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) { 45 return res; 46 } 47 } 48 49 return MP_OKAY; 50 } 51 #endif 52 53 /* $Source: /cvs/libtom/libtommath/bn_mp_rand.c,v $ */ 54 /* $Revision: 1.3 $ */ 55 /* $Date: 2006/03/31 14:18:44 $ */ 56
