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#include "tommath_private.h"
#ifdef BN_MP_DR_IS_MODULUS_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.
*
* SPDX-License-Identifier: Unlicense
*/
/* determines if a number is a valid DR modulus */
int mp_dr_is_modulus(const mp_int *a)
{
int ix;
/* must be at least two digits */
if (a->used < 2) {
return 0;
}
/* must be of the form b**k - a [a <= b] so all
* but the first digit must be equal to -1 (mod b).
*/
for (ix = 1; ix < a->used; ix++) {
if (a->dp[ix] != MP_MASK) {
return 0;
}
}
return 1;
}
#endif
/* ref: HEAD -> master, tag: v1.1.0 */
/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */
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