view libtommath/bn_mp_read_radix.c @ 1659:d32bcb5c557d

Add Ed25519 support (#91) * Add support for Ed25519 as a public key type Ed25519 is a elliptic curve signature scheme that offers better security than ECDSA and DSA and good performance. It may be used for both user and host keys. OpenSSH key import and fuzzer are not supported yet. Initially inspired by Peter Szabo. * Add curve25519 and ed25519 fuzzers * Add import and export of Ed25519 keys
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Wed, 11 Mar 2020 21:09:45 +0500
parents f52919ffd3b1
children 1051e4eea25a
line wrap: on
line source

#include "tommath_private.h"
#ifdef BN_MP_READ_RADIX_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
 */

/* read a string [ASCII] in a given radix */
int mp_read_radix(mp_int *a, const char *str, int radix)
{
   int     y, res, neg;
   unsigned pos;
   char    ch;

   /* zero the digit bignum */
   mp_zero(a);

   /* make sure the radix is ok */
   if ((radix < 2) || (radix > 64)) {
      return MP_VAL;
   }

   /* if the leading digit is a
    * minus set the sign to negative.
    */
   if (*str == '-') {
      ++str;
      neg = MP_NEG;
   } else {
      neg = MP_ZPOS;
   }

   /* set the integer to the default of zero */
   mp_zero(a);

   /* process each digit of the string */
   while (*str != '\0') {
      /* if the radix <= 36 the conversion is case insensitive
       * this allows numbers like 1AB and 1ab to represent the same  value
       * [e.g. in hex]
       */
      ch = (radix <= 36) ? (char)toupper((int)*str) : *str;
      pos = (unsigned)(ch - '(');
      if (mp_s_rmap_reverse_sz < pos) {
         break;
      }
      y = (int)mp_s_rmap_reverse[pos];

      /* if the char was found in the map
       * and is less than the given radix add it
       * to the number, otherwise exit the loop.
       */
      if ((y == 0xff) || (y >= radix)) {
         break;
      }
      if ((res = mp_mul_d(a, (mp_digit)radix, a)) != MP_OKAY) {
         return res;
      }
      if ((res = mp_add_d(a, (mp_digit)y, a)) != MP_OKAY) {
         return res;
      }
      ++str;
   }

   /* if an illegal character was found, fail. */
   if (!((*str == '\0') || (*str == '\r') || (*str == '\n'))) {
      mp_zero(a);
      return MP_VAL;
   }

   /* set the sign only if a != 0 */
   if (mp_iszero(a) != MP_YES) {
      a->sign = neg;
   }
   return MP_OKAY;
}
#endif

/* ref:         HEAD -> master, tag: v1.1.0 */
/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */