Mercurial > dropbear

view libtommath/bn_mp_invmod.c @ 1861:2b3a8026a6ce

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add re-exec for server This allows ASLR to re-randomize the address space for every connection, preventing some vulnerabilities from being exploitable by repeated probing. Overhead (memory and time) is yet to be confirmed. At present this is only enabled on Linux. Other BSD platforms with fexecve() would probably also work though have not been tested.
author Matt Johnston <matt@ucc.asn.au>
date Sun, 30 Jan 2022 10:14:56 +0800
parents 1051e4eea25a
children
line wrap: on
line source

#include "tommath_private.h"
#ifdef BN_MP_INVMOD_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* hac 14.61, pp608 */
mp_err mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
{
   /* b cannot be negative and has to be >1 */
   if ((b->sign == MP_NEG) || (mp_cmp_d(b, 1uL) != MP_GT)) {
      return MP_VAL;
   }

   /* if the modulus is odd we can use a faster routine instead */
   if (MP_HAS(S_MP_INVMOD_FAST) && MP_IS_ODD(b)) {
      return s_mp_invmod_fast(a, b, c);
   }

   return MP_HAS(S_MP_INVMOD_SLOW)
          ? s_mp_invmod_slow(a, b, c)
          : MP_VAL;
}
#endif