masking credit card & bank account information - php

Question

I'm looking for a php function which can mask credit card & bank information such as routing number and account numbers. I need to mask many formats, so the existing stack overflow answers don't help me that much.
So for example, if the input is 304-443-2456, the function should return xxx-xxx-2456.
Sometimes the number has dashes, and can be in various lengths.
I'm looking for something generic, that I can extend as needed, preferably a zend framework view helper class.

Answer 1

Some little regex in a function of it own, configuration available:
$number = '304-443-2456';
function mask_number($number, $count = 4, $seperators = '-')
{
$masked = preg_replace('/\d/', 'x', $number);
$last = preg_match(sprintf('/([%s]?\d){%d}$/', preg_quote($seperators), $count), $number, $matches);
if ($last) {
list($clean) = $matches;
$masked = substr($masked, 0, -strlen($clean)) . $clean;
}
return $masked;
}
echo mask_number($number); # xxx-xxx-2456
If the function fails, it will return all masked (e.g. a different seperator, less than 4 digits etc.). Some child-safety build in you could say.
Demo

Answer 2

<?php
function ccmask($cc, $char = '#') {
$pattern = '/^([0-9-]+)([0-9]*)$/U';
$matches = array();
preg_match($pattern, $cc, $matches);
return preg_replace('([0-9])', $char, $matches[1]).$matches[2];
}
echo ccmask('304-443-2456'), "\n";
echo ccmask('4924-7921-9900-9876', '*'), "\n";
echo ccmask('30-43-56', 'x'), "\n";
Outputs:
###-###-2456
****-****-****-9876
xx-xx-56

Answer 3

I use a view helper for that. I tend to avoid Regex though as it always takes me ages to work out what it does, especially if I come back to code after a while.
class Zend_View_Helper_Ccmask
{
public function ccmask($ccNum)
{
$maskArray = explode('-', $ccNum);
$sections = count($maskArray) - 1;
for($i = 0; $i < $sections ; $i++){
$maskArray[$i] = str_replace(array(1,2,3,4,5,6,7,8,9,0), 'x', $maskArray[$i]);
}
return implode('-', $maskArray);
}
}
In your view
echo $this->ccmask('304-443-2456');
//output = xxx-xxx-2456

Answer 4

A good way to look at this is at what won't be masked and outputing xs for everything else. A simple, inexpensive solution is:
function cc_mask( $cc_raw, $unmask_count ){
$cc_masked = '';
for( $i=0; $i < ( strlen( $cc_raw ) - $unmask_count ) ; $i++ ){
//If you want to maintain hyphens and special characters
$char = substr( $cc_raw, $i, 1 );
$cc_masked .= ctype_digit( $char ) ? "*" : $char;
}
$cc_masked .= substr( $cc_raw , -$unmask_count );
return $cc_masked;
}
echo cc_mask("304-443-2456",4);
//Output
***-***-2456
Would be even faster if there was no need to maintain the hyphens and special characters