Question

Can anyone provide an algorithm to validate a Singaporean FIN?

I know with a Singaporean NRIC I can validate it via modulo 11 and then compare the result to a lookup table but cannot find a similar lookup table for the FIN.

I also do not know for sure if the modulo 11 is the correct method to validate.

I am aware the government sells a algorithm for $400 but maybe someone knows a cheaper way.

Bonus points for c# implementation.

Answer 1

After a little searching around I found a way to validate them. This doesn’t neccersarily mean the FIN is valid, just that it falls within a valid range.

I based it on algorithms from http://www.ngiam.net/NRIC/ppframe.htm

I’ve also included a similar method for checking NRIC because I figure anyone who comes across this and is interested in one is interested in the other as well.

Hope this helps someone!

    private static readonly int[] Multiples = { 2, 7, 6, 5, 4, 3, 2 };      public static bool IsNricValid(string nric)     {         if (string.IsNullOrEmpty(nric))         {             return false;         }          //  check length         if (nric.Length != 9)         {             return false;         }          int total = 0             , count = 0             , numericNric;         char first = nric[0]             , last = nric[nric.Length - 1];          if (first != 'S' && first != 'T')         {             return false;         }          if (!int.TryParse(nric.Substring(1, nric.Length - 2), out numericNric))         {             return false;         }          while (numericNric != 0)         {             total += numericNric % 10 * Multiples[Multiples.Length - (1 + count++)];              numericNric /= 10;         }          char[] outputs;         if (first == 'S')         {             outputs = new char[] { 'J', 'Z', 'I', 'H', 'G', 'F', 'E', 'D', 'C', 'B', 'A' };         }         else         {             outputs = new char[] { 'G', 'F', 'E', 'D', 'C', 'B', 'A', 'J', 'Z', 'I', 'H' };         }          return last == outputs[total % 11];      }      public static bool IsFinValid(string fin)     {         if (string.IsNullOrEmpty(fin))         {             return false;         }          //  check length         if (fin.Length != 9)         {             return false;         }          int total = 0             , count = 0             , numericNric;         char first = fin[0]             , last = fin[fin.Length - 1];          if (first != 'F' && first != 'G')         {             return false;         }          if (!int.TryParse(fin.Substring(1, fin.Length - 2), out numericNric))         {             return false;         }          while (numericNric != 0)         {             total += numericNric % 10 * Multiples[Multiples.Length - (1 + count++)];              numericNric /= 10;         }          char[] outputs;         if (first == 'F')         {             outputs = new char[] { 'X', 'W', 'U', 'T', 'R', 'Q', 'P', 'N', 'M', 'L', 'K' };         }         else         {             outputs = new char[] { 'R', 'Q', 'P', 'N', 'M', 'L', 'K', 'X', 'W', 'U', 'T' };         }          return last == outputs[total % 11];     }