anastasis

Credential backup and recovery protocol and service
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validation_DE_SVN.c (2558B)

      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_DE_SVN.c
     18  * @brief
     19  * @author Christian Grothoff
     20  * @author Dominik Meister
     21  * @author Dennis Neufeld
     22  */
     23 #include <string.h>
     24 #include <stdbool.h>
     25 
     26 /**
     27  * Sum up all digits in @a v and return the result.
     28  */
     29 static unsigned int
     30 q (unsigned int v)
     31 {
     32   unsigned int r = 0;
     33 
     34   while (0 != v)
     35   {
     36     r += v % 10;
     37     v = v / 10;
     38   }
     39   return r;
     40 }
     41 
     42 
     43 /**
     44  * Function to validate a German Social Security number.
     45  *
     46  * See https://www.financescout24.de/wissen/ratgeber/sozialversicherungsnummer
     47  * and https://de.wikipedia.org/wiki/Versicherungsnummer
     48  * for the structure!
     49  *
     50  * @param ssn_number social security number to validate (input)
     51  * @return true if validation passed, else false
     52  */
     53 bool
     54 DE_SVN_check (const char *ssn_number);
     55 
     56 /* declaration to fix compiler warning */
     57 bool
     58 DE_SVN_check (const char *ssn_number)
     59 {
     60   static const unsigned int factors[] = {
     61     2, 1, 2, 5, 7, 1, 2, 1, 2, 1, 2, 1
     62   };
     63   unsigned int sum = 0;
     64 
     65   if (strlen (ssn_number) != 12)
     66     return false;
     67   for (unsigned int i = 0; i<8; i++)
     68   {
     69     unsigned char c = (unsigned char) ssn_number[i];
     70 
     71     if ( ('0' > c) || ('9' < c) )
     72       return false;
     73     sum += q ((c - '0') * factors[i]);
     74   }
     75   {
     76     unsigned char c = (unsigned char) ssn_number[8];
     77     unsigned int v = (c - 'A' + 1);
     78 
     79     if ( ('A' > c) || ('Z' < c) )
     80       return false;
     81     sum += q ((v / 10) * factors[8]);
     82     sum += q ((v % 10) * factors[9]);
     83   }
     84   for (unsigned int i = 9; i<11; i++)
     85   {
     86     unsigned char c = ssn_number[i];
     87 
     88     if ( ('0' > c) || ('9' < c) )
     89       return false;
     90     sum += q ((c - '0') * factors[i + 1]);
     91   }
     92   if (ssn_number[11] != '0' + (sum % 10))
     93     return false;
     94   {
     95     unsigned int month = (ssn_number[4] - '0') * 10 + (ssn_number[5] - '0');
     96 
     97     if ( (0 == month) ||
     98          (12 < month) )
     99       return false;
    100   }
    101   return true;
    102 }