iban_converter.inc.php

<?php

class IbanConverter
{
  function convert_dk($input) {
    // DKkk BBBB CCCC CCCC CC
    $iban = "DK00" .
      str_pad($input['dk_bank_reg_number'], 4, "0", STR_PAD_LEFT) .
      str_pad($input['dk_bank_account_number'], 10, "0", STR_PAD_LEFT);
    $this->iban_replace_checksum($iban);
  }

  protected function iban_replace_checksum($iban) {
    $checksum = $this->iban_find_checksum($iban);
    return substr($iban, 0, 2) . str_pad($checksum, 2, "0", STR_PAD_LEFT) . substr($iban, 4);
  }


  protected function iban_find_checksum($iban) {
    $iban = $this->iban_to_machine_format($iban);
    // move first 4 chars to right
    $left = substr($iban, 0, 2) . '00'; // but set right-most 2 (checksum) to '00'
    $right = substr($iban, 4);
    // glue back together
    $tmp = $right . $left;
    // convert letters using conversion table
    $tmp = $this->iban_checksum_string_replace($tmp);
    // get mod97-10 output
    $checksum = $this->iban_mod97_10($tmp);
    return (98 - $checksum);
  }

  // Convert an IBAN to machine format.  To do this, we
  // remove IBAN from the start, if present, and remove
  // non basic roman letter / digit characters
  protected function iban_to_machine_format($iban) {
    // Uppercase and trim spaces from left
    $iban = ltrim(strtoupper($iban));
    // Remove IBAN from start of string, if present
    $iban = preg_replace('/^IBAN/', '', $iban);
    // Remove all non basic roman letter / digit characters
    $iban = preg_replace('/[^A-Z0-9]/', '', $iban);
    return $iban;
  }

  // Character substitution required for IBAN MOD97-10 checksum validation/generation
  //  $s  Input string (IBAN)
  protected function iban_checksum_string_replace($s) {
    $iban_replace_chars = range('A', 'Z');
    foreach (range(10, 35) as $tempvalue) {
      $iban_replace_values[] = strval($tempvalue);
    }
    return str_replace($iban_replace_chars, $iban_replace_values, $s);
  }

  // Perform MOD97-10 checksum calculation
  //  $s  Input string (IBAN)
  protected function iban_mod97_10($s) {
    $tr = intval(substr($s, 0, 1));
    for ($pos = 1; $pos < strlen($s); $pos++) {
      $tr *= 10;
      $tr += intval(substr($s, $pos, 1));
      $tr %= 97;
    }
    return $tr;
  }
}