view libtommath/bn_mp_reduce_setup.c @ 1928:333688ec53d0

Handle ecdsa-sk flags, reject no-touch For the time being Dropbear will only allow SK auth with default parameters, user-presence needs to be set. In future handling of authorized_keys option "no-touch-required" can be added. This code would also be refactored to share between ecdsa and ed25519 once I get hardware/emulation to test ed25519.
author Matt Johnston <matt@ucc.asn.au>
date Wed, 30 Mar 2022 21:06:15 +0800
parents 1051e4eea25a
children
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#include "tommath_private.h"
#ifdef BN_MP_REDUCE_SETUP_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* pre-calculate the value required for Barrett reduction
 * For a given modulus "b" it calulates the value required in "a"
 */
mp_err mp_reduce_setup(mp_int *a, const mp_int *b)
{
   mp_err err;
   if ((err = mp_2expt(a, b->used * 2 * MP_DIGIT_BIT)) != MP_OKAY) {
      return err;
   }
   return mp_div(a, b, a, NULL);
}
#endif