1 #include <tommath.h> 2 #ifdef BN_MP_DR_IS_MODULUS_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 /* determines if a number is a valid DR modulus */ 19 int mp_dr_is_modulus(mp_int *a) 20 { 21 int ix; 22 23 /* must be at least two digits */ 24 if (a->used < 2) { 25 return 0; 26 } 27 28 /* must be of the form b**k - a [a <= b] so all 29 * but the first digit must be equal to -1 (mod b). 30 */ 31 for (ix = 1; ix < a->used; ix++) { 32 if (a->dp[ix] != MP_MASK) { 33 return 0; 34 } 35 } 36 return 1; 37 } 38 39 #endif 40 41 /* $Source: /cvs/libtom/libtommath/bn_mp_dr_is_modulus.c,v $ */ 42 /* $Revision: 1.3 $ */ 43 /* $Date: 2006/03/31 14:18:44 $ */ 44
