1 #include <tommath.h> 2 #ifdef BN_MP_PRIME_IS_PRIME_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 /* performs a variable number of rounds of Miller-Rabin 19 * 20 * Probability of error after t rounds is no more than 21 22 * 23 * Sets result to 1 if probably prime, 0 otherwise 24 */ 25 int mp_prime_is_prime (mp_int * a, int t, int *result) 26 { 27 mp_int b; 28 int ix, err, res; 29 30 /* default to no */ 31 *result = MP_NO; 32 33 /* valid value of t? */ 34 if (t <= 0 || t > PRIME_SIZE) { 35 return MP_VAL; 36 } 37 38 /* is the input equal to one of the primes in the table? */ 39 for (ix = 0; ix < PRIME_SIZE; ix++) { 40 if (mp_cmp_d(a, ltm_prime_tab[ix]) == MP_EQ) { 41 *result = 1; 42 return MP_OKAY; 43 } 44 } 45 46 /* first perform trial division */ 47 if ((err = mp_prime_is_divisible (a, &res)) != MP_OKAY) { 48 return err; 49 } 50 51 /* return if it was trivially divisible */ 52 if (res == MP_YES) { 53 return MP_OKAY; 54 } 55 56 /* now perform the miller-rabin rounds */ 57 if ((err = mp_init (&b)) != MP_OKAY) { 58 return err; 59 } 60 61 for (ix = 0; ix < t; ix++) { 62 /* set the prime */ 63 mp_set (&b, ltm_prime_tab[ix]); 64 65 if ((err = mp_prime_miller_rabin (a, &b, &res)) != MP_OKAY) { 66 goto LBL_B; 67 } 68 69 if (res == MP_NO) { 70 goto LBL_B; 71 } 72 } 73 74 /* passed the test */ 75 *result = MP_YES; 76 LBL_B:mp_clear (&b); 77 return err; 78 } 79 #endif 80 81 /* $Source: /cvs/libtom/libtommath/bn_mp_prime_is_prime.c,v $ */ 82 /* $Revision: 1.3 $ */ 83 /* $Date: 2006/03/31 14:18:44 $ */ 84
