NAME

CheckDigits::MXX_001 - compute check digits for german Personalausweis (pa_de) or ABA routing numbers (aba_rn)

SYNOPSIS

  use Algorithm::CheckDigits;
  $pa = CheckDigits('pa_de');
  if ($pa->is_valid('2406055684D<<6810203<0705109<6')) {
        # do something
  }
  if ($pa->is_valid('2406055684') {
        # do_something
  }
  $cn = $pa->complete('240605568_D<<681020_<070510_<_');
  # $cn = '2406055684D<<6810203<0705109<6'
  $cd = $pa->checkdigit('2406055684D<<6810203<0705109<6');
  # $cd = '6'
  $bn = $pa->basenumber('2406055684D<<6810203<0705109<6');
  # $bn = '240605568_D<<681020_<070510_<_'
  $aba = CheckDigits('aba_rn');
  if ($aba->is_valid('789456124')) {
       # do something
  }

DESCRIPTION

ALGORITHM

1.: Beginning left all digits are weighted with 7,3,1,7,3,1,... for pa_de or 3,7,1,3,7,1,3,7,1 for aba_rn.
2.: The sum of those products is computed.
3.: For pa_de the checksum is the last digit of the sum from step 2 (modulo 10).
For aba_rn the checksum is the difference of the sum from step 2 to the next multiple of 10.
4.: For the german Personalausweis step 1 to 3 is performed for every part of the number and for all 3 parts including the particular checkdigit to compute the total checksum.
If the number solely consists of digits, the checksum is just computed once according to algorithm given above.

METHODS

is_valid($number): Returns true only if $number consists solely of numbers and the last digit is a valid check digit according to the algorithm given above.
Returns false otherwise,
complete($number): The check digit for $number is computed and concatenated to the end of $number.
Returns the complete number with check digit or '' if $number does not consist solely of digits and spaces.
basenumber($number): Returns the basenumber of $number if $number has a valid check digit.
Return '' otherwise.
checkdigit($number): Returns the checkdigit of $number if $number has a valid check digit.
Return '' otherwise.

EXPORT

None by default.

AUTHOR

Mathias Weidner, "<mamawe@cpan.org>"

THANKS

Aaron W. West pointed me to a fault in the computing of the check digit. Jim Hickstein made me aware of the ABA routing numbers.