anastasis

Credential backup and recovery protocol and service
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validation_CH_AHV.c (1742B)


      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_CH_AHV.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 
     26 /**
     27  * Function to validate a Swiss AHV number.
     28  *
     29  * @param ahv_number ahv number to validate (input)
     30  * @return true if validation passed, else false
     31  */
     32 bool
     33 CH_AHV_check (const char *ahv_number);
     34 
     35 /* declaration to fix compiler warning */
     36 bool
     37 CH_AHV_check (const char *ahv_number)
     38 {
     39   unsigned int checknum;
     40   unsigned int next_ten;
     41   const char *pos = &ahv_number[strlen (ahv_number) - 1];
     42   bool phase = true;
     43   unsigned int calculation = 0;
     44 
     45   checknum = *pos - 48;
     46   while (pos > ahv_number)
     47   {
     48     pos--;
     49     if ('.' == *pos)
     50       continue;
     51     if (phase)
     52       calculation += ((*pos - 48) * 3);
     53     else
     54       calculation += *pos - 48;
     55     phase = ! phase;
     56   }
     57   /* round up to the next ten */
     58   next_ten = ((calculation + 9) / 10) * 10;
     59   calculation = next_ten - calculation;
     60   return (checknum == calculation);
     61 }