Masking credit card number

What is the best way to mask credit card number in PHP?

The credit card number doesn't have to be valid. So no need to do a Luhn Algorithm. As long as it matches the pattern replace it with XXXXXXXX.

What I have so far:

<?php

$str = "The quick brown fox jumps over 5192696222257727 dog.";

$credit_card_re = '/^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6011[0-9]{12}|622((12[6-9]|1[3-9][0-9])|([2-8][0-9][0-9])|(9(([0-1][0-9])|(2[0-5]))))[0-9]{10}|64[4-9][0-9]{13}|65[开发者_StackOverflow中文版0-9]{14}|3(?:0[0-5]|[68][0-9])[0-9]{11}|3[47][0-9]{13})*$/';

$cc = "6789765435678765";
$cc = str_pad(substr($cc, -4), strlen($cc), '*', STR_PAD_LEFT);

Regular expressions will work fine, so what you have is good.

To actually do the regex, use this code:

$str = "The quick brown fox jumps over 5192696222257727 dog.";

$masked = preg_replace("/(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6(?:011|5[0-9][0-9])[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\d{3})\d{11})/", "XXXXXXXX", $str);

Then you can do whatever with $masked.

EDIT: Fixed the regex, yours only matches it if the entire string is the number.

A no regex solution, that works for any length string, to show only last 4:

function mask_cc( $number )  {

    return  substr_replace($number, str_repeat('X', strlen( $number ) - 4), 0, strlen( $number ) - 4);

}

http://www.php.net/manual/en/function.preg-replace.php

<?php

$str = "The quick brown fox jumps over 5192696222257727 dog.";

$pattern = '/^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6011[0-9]{12}|622((12[6-9]|1[3-9][0-9])|([2-8][0-9][0-9])|(9(([0-1][0-9])|(2[0-5]))))[0-9]{10}|64[4-9][0-9]{13}|65[0-9]{14}|3(?:0[0-5]|[68][0-9])[0-9]{11}|3[47][0-9]{13})*$/';

$str = preg_replace($pattern , 'XXXXXXXX' , $str);

? Or don't I understand you?

<?php
    function mask ( $str, $start = 0, $length = null ) {
        $mask = preg_replace ( "/\S/", "*", $str );
        if ( is_null ( $length )) {
            $mask = substr ( $mask, $start );
            $str = substr_replace ( $str, $mask, $start );
        } else {
            $mask = substr ( $mask, $start, $length );
            $str = substr_replace ( $str, $mask, $start, $length );
        }
        return $str;
    }
?>

Look here