anastasis

Credential backup and recovery protocol and service
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validation_XY_PRIME.c (1643B)


      1 /*
      2   This file is part of Anastasis
      3   Copyright (C) 2020, 2021 Anastasis SARL
      4 
      5   Anastasis is free software; you can redistribute it and/or modify it under the
      6   terms of the GNU General Public License as published by the Free Software
      7   Foundation; either version 3, or (at your option) any later version.
      8 
      9   Anastasis is distributed in the hope that it will be useful, but WITHOUT ANY
     10   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
     11   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
     12 
     13   You should have received a copy of the GNU General Public License along with
     14   Anastasis; see the file COPYING.GPL.  If not, see <http://www.gnu.org/licenses/>
     15 */
     16 /**
     17  * @file reducer/validation_XY_PRIME.c
     18  * @brief anastasis reducer api
     19  * @author Christian Grothoff
     20  * @author Dominik Meister
     21  * @author Dennis Neufeld
     22  */
     23 #include <string.h>
     24 #include <stdbool.h>
     25 #include <stdio.h>
     26 #include <gcrypt.h>
     27 
     28 /**
     29  * Function to validate a prime number.
     30  *
     31  * @param pr_number prime number to validate (input)
     32  * @return true if pr_number is a prime, else false
     33  */
     34 bool
     35 XY_PRIME_check (const char *pr_number);
     36 
     37 /* declaration to fix compiler warning */
     38 bool
     39 XY_PRIME_check (const char *pr_number)
     40 {
     41   unsigned long long n;
     42   char dummy;
     43   gcry_mpi_t p;
     44   bool is_prime;
     45 
     46   if (1 != sscanf (pr_number,
     47                    "%llu%c",
     48                    &n,
     49                    &dummy))
     50     return false;
     51   p = gcry_mpi_set_ui (NULL,
     52                        (unsigned long) n);
     53   is_prime = (0 == gcry_prime_check (p,
     54                                      0));
     55   gcry_mpi_release (p);
     56   return is_prime;
     57 }