Validate IBAN PHP

Question

As designing a new platform we tried to integrate the IBAN numbers. We have to make sure that the IBAN is validated and the IBAN stored to the database is always correct. So what would be a proper way to validate the number?

Answer 1

Slight modification of @PeterFox answer including support for bcmod() when bcmath is not available,

<?php

function isValidIBAN ($iban) {

  $iban = strtolower($iban);
  $Countries = array(
    'al'=>28,'ad'=>24,'at'=>20,'az'=>28,'bh'=>22,'be'=>16,'ba'=>20,'br'=>29,'bg'=>22,'cr'=>21,'hr'=>21,'cy'=>28,'cz'=>24,
    'dk'=>18,'do'=>28,'ee'=>20,'fo'=>18,'fi'=>18,'fr'=>27,'ge'=>22,'de'=>22,'gi'=>23,'gr'=>27,'gl'=>18,'gt'=>28,'hu'=>28,
    'is'=>26,'ie'=>22,'il'=>23,'it'=>27,'jo'=>30,'kz'=>20,'kw'=>30,'lv'=>21,'lb'=>28,'li'=>21,'lt'=>20,'lu'=>20,'mk'=>19,
    'mt'=>31,'mr'=>27,'mu'=>30,'mc'=>27,'md'=>24,'me'=>22,'nl'=>18,'no'=>15,'pk'=>24,'ps'=>29,'pl'=>28,'pt'=>25,'qa'=>29,
    'ro'=>24,'sm'=>27,'sa'=>24,'rs'=>22,'sk'=>24,'si'=>19,'es'=>24,'se'=>24,'ch'=>21,'tn'=>24,'tr'=>26,'ae'=>23,'gb'=>22,'vg'=>24
  );
  $Chars = array(
    'a'=>10,'b'=>11,'c'=>12,'d'=>13,'e'=>14,'f'=>15,'g'=>16,'h'=>17,'i'=>18,'j'=>19,'k'=>20,'l'=>21,'m'=>22,
    'n'=>23,'o'=>24,'p'=>25,'q'=>26,'r'=>27,'s'=>28,'t'=>29,'u'=>30,'v'=>31,'w'=>32,'x'=>33,'y'=>34,'z'=>35
  );

  if (strlen($iban) != $Countries[ substr($iban,0,2) ]) { return false; }

  $MovedChar = substr($iban, 4) . substr($iban,0,4);
  $MovedCharArray = str_split($MovedChar);
  $NewString = "";

  foreach ($MovedCharArray as $k => $v) {

    if ( !is_numeric($MovedCharArray[$k]) ) {
      $MovedCharArray[$k] = $Chars[$MovedCharArray[$k]];
    }
    $NewString .= $MovedCharArray[$k];
  }
  if (function_exists("bcmod")) { return bcmod($NewString, '97') == 1; }

  // http://au2.php.net/manual/en/function.bcmod.php#38474
  $x = $NewString; $y = "97";
  $take = 5; $mod = "";

  do {
    $a = (int)$mod . substr($x, 0, $take);
    $x = substr($x, $take);
    $mod = $a % $y;
  }
  while (strlen($x));

  return (int)$mod == 1;
}

Answer 2

Sorry, I can not yet comment due to low Rep, so the new link to user3733632s answer:

https://github.com/globalcitizen/php-iban

(the project is no longer hosted at google code as of March 2015, and the project will get a new version after some cleanup.)

Answer 3

As the logic was explained in my other question I've tried to create a function myself. Based on the logic explained in the wikipedia article find a proper function below. Country specific validation.

Will it fit the

http://en.wikipedia.org/wiki/International_Bank_Account_Number#Validating_the_IBAN

function checkIBAN($iban)
{
    $iban = strtolower(str_replace(' ','',$iban));
    $Countries = array('al'=>28,'ad'=>24,'at'=>20,'az'=>28,'bh'=>22,'be'=>16,'ba'=>20,'br'=>29,'bg'=>22,'cr'=>21,'hr'=>21,'cy'=>28,'cz'=>24,'dk'=>18,'do'=>28,'ee'=>20,'fo'=>18,'fi'=>18,'fr'=>27,'ge'=>22,'de'=>22,'gi'=>23,'gr'=>27,'gl'=>18,'gt'=>28,'hu'=>28,'is'=>26,'ie'=>22,'il'=>23,'it'=>27,'jo'=>30,'kz'=>20,'kw'=>30,'lv'=>21,'lb'=>28,'li'=>21,'lt'=>20,'lu'=>20,'mk'=>19,'mt'=>31,'mr'=>27,'mu'=>30,'mc'=>27,'md'=>24,'me'=>22,'nl'=>18,'no'=>15,'pk'=>24,'ps'=>29,'pl'=>28,'pt'=>25,'qa'=>29,'ro'=>24,'sm'=>27,'sa'=>24,'rs'=>22,'sk'=>24,'si'=>19,'es'=>24,'se'=>24,'ch'=>21,'tn'=>24,'tr'=>26,'ae'=>23,'gb'=>22,'vg'=>24);
    $Chars = array('a'=>10,'b'=>11,'c'=>12,'d'=>13,'e'=>14,'f'=>15,'g'=>16,'h'=>17,'i'=>18,'j'=>19,'k'=>20,'l'=>21,'m'=>22,'n'=>23,'o'=>24,'p'=>25,'q'=>26,'r'=>27,'s'=>28,'t'=>29,'u'=>30,'v'=>31,'w'=>32,'x'=>33,'y'=>34,'z'=>35);

    if(strlen($iban) == $Countries[substr($iban,0,2)]){

        $MovedChar = substr($iban, 4).substr($iban,0,4);
        $MovedCharArray = str_split($MovedChar);
        $NewString = "";

        foreach($MovedCharArray AS $key => $value){
            if(!is_numeric($MovedCharArray[$key])){
                $MovedCharArray[$key] = $Chars[$MovedCharArray[$key]];
            }
            $NewString .= $MovedCharArray[$key];
        }

        if(bcmod($NewString, '97') == 1)
        {
            return true;
        }
        else{
            return false;
        }
    }
    else{
        return false;
    }   
}

Answer 4

top rated function does NOT work.

Just try a string with '%' in it...

I'm using this one :

function checkIBAN($iban) {

// Normalize input (remove spaces and make upcase)
$iban = strtoupper(str_replace(' ', '', $iban));

if (preg_match('/^[A-Z]{2}[0-9]{2}[A-Z0-9]{1,30}$/', $iban)) {
    $country = substr($iban, 0, 2);
    $check = intval(substr($iban, 2, 2));
    $account = substr($iban, 4);

    // To numeric representation
    $search = range('A','Z');
    foreach (range(10,35) as $tmp)
        $replace[]=strval($tmp);
    $numstr=str_replace($search, $replace, $account.$country.'00');

    // Calculate checksum
    $checksum = intval(substr($numstr, 0, 1));
    for ($pos = 1; $pos < strlen($numstr); $pos++) {
        $checksum *= 10;
        $checksum += intval(substr($numstr, $pos,1));
        $checksum %= 97;
    }

    return ((98-$checksum) == $check);
} else
    return false;
}

Answer 5

The accepted answer is not the preferred way of validation, the specification dictates the following:

 1. Check that the total IBAN length is correct as per the country. If not, the IBAN is invalid
 2. Replace the two check digits by 00 (e.g. GB00 for the UK)
 3. Move the four initial characters to the end of the string
 4. Replace the letters in the string with digits, expanding the string as necessary, such that A or a = 10,
    B or b = 11, and Z or z = 35. Each alphabetic character is therefore replaced by 2 digits
 5. Convert the string to an integer (i.e. ignore leading zeroes)
 6. Calculate mod-97 of the new number, which results in the remainder
 7. Subtract the remainder from 98, and use the result for the two check digits. If the result is a single digit
   number, pad it with a leading 0 to make a two-digit number

I've written a class that validates, formats and parses strings according to the spec, hope this helps save some the time to roll their own. Code found here:

https://gist.github.com/esserj/a54ffd11182417cf920d

Answer 6

Google Code hosts a project of an open source php-iban validator: https://code.google.com/p/php-iban/