4e3f1344a5
tommath.h contains declarations for the public part of the library. tommath_private.h contains the functions which are private to ltm and should not be exposed to the public.
110 lines
3.1 KiB
C
110 lines
3.1 KiB
C
#include <tommath_private.h>
|
|
#ifdef BN_MP_IS_SQUARE_C
|
|
/* LibTomMath, multiple-precision integer library -- Tom St Denis
|
|
*
|
|
* LibTomMath is a library that provides multiple-precision
|
|
* integer arithmetic as well as number theoretic functionality.
|
|
*
|
|
* The library was designed directly after the MPI library by
|
|
* Michael Fromberger but has been written from scratch with
|
|
* additional optimizations in place.
|
|
*
|
|
* The library is free for all purposes without any express
|
|
* guarantee it works.
|
|
*
|
|
* Tom St Denis, tstdenis82@gmail.com, http://libtom.org
|
|
*/
|
|
|
|
/* Check if remainders are possible squares - fast exclude non-squares */
|
|
static const char rem_128[128] = {
|
|
0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1
|
|
};
|
|
|
|
static const char rem_105[105] = {
|
|
0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,
|
|
0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1,
|
|
0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1,
|
|
0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1,
|
|
1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1,
|
|
1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1
|
|
};
|
|
|
|
/* Store non-zero to ret if arg is square, and zero if not */
|
|
int mp_is_square(mp_int *arg,int *ret)
|
|
{
|
|
int res;
|
|
mp_digit c;
|
|
mp_int t;
|
|
unsigned long r;
|
|
|
|
/* Default to Non-square :) */
|
|
*ret = MP_NO;
|
|
|
|
if (arg->sign == MP_NEG) {
|
|
return MP_VAL;
|
|
}
|
|
|
|
/* digits used? (TSD) */
|
|
if (arg->used == 0) {
|
|
return MP_OKAY;
|
|
}
|
|
|
|
/* First check mod 128 (suppose that DIGIT_BIT is at least 7) */
|
|
if (rem_128[127 & DIGIT(arg,0)] == 1) {
|
|
return MP_OKAY;
|
|
}
|
|
|
|
/* Next check mod 105 (3*5*7) */
|
|
if ((res = mp_mod_d(arg,105,&c)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
if (rem_105[c] == 1) {
|
|
return MP_OKAY;
|
|
}
|
|
|
|
|
|
if ((res = mp_init_set_int(&t,11L*13L*17L*19L*23L*29L*31L)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
if ((res = mp_mod(arg,&t,&t)) != MP_OKAY) {
|
|
goto ERR;
|
|
}
|
|
r = mp_get_int(&t);
|
|
/* Check for other prime modules, note it's not an ERROR but we must
|
|
* free "t" so the easiest way is to goto ERR. We know that res
|
|
* is already equal to MP_OKAY from the mp_mod call
|
|
*/
|
|
if (((1L<<(r%11)) & 0x5C4L) != 0L) goto ERR;
|
|
if (((1L<<(r%13)) & 0x9E4L) != 0L) goto ERR;
|
|
if (((1L<<(r%17)) & 0x5CE8L) != 0L) goto ERR;
|
|
if (((1L<<(r%19)) & 0x4F50CL) != 0L) goto ERR;
|
|
if (((1L<<(r%23)) & 0x7ACCA0L) != 0L) goto ERR;
|
|
if (((1L<<(r%29)) & 0xC2EDD0CL) != 0L) goto ERR;
|
|
if (((1L<<(r%31)) & 0x6DE2B848L) != 0L) goto ERR;
|
|
|
|
/* Final check - is sqr(sqrt(arg)) == arg ? */
|
|
if ((res = mp_sqrt(arg,&t)) != MP_OKAY) {
|
|
goto ERR;
|
|
}
|
|
if ((res = mp_sqr(&t,&t)) != MP_OKAY) {
|
|
goto ERR;
|
|
}
|
|
|
|
*ret = (mp_cmp_mag(&t,arg) == MP_EQ) ? MP_YES : MP_NO;
|
|
ERR:mp_clear(&t);
|
|
return res;
|
|
}
|
|
#endif
|
|
|
|
/* $Source$ */
|
|
/* $Revision$ */
|
|
/* $Date$ */
|