Convert MD5 to base62 for URL

Question

I have a script to convert to base 62 (A-Za-z0-9) but how do I get a number out of MD5?

I have read in many places that because the number from an MD5 is bigger than

Answer 1

You could use a slightly modified Base 64 with - and _ instead of + and /:

function base64_url_encode($str) {
    return strtr(base64_encode($str), array('+'=>'-', '/'=>'_'));
}
function base64_url_decode($str) {
    return base64_decode(strtr($str, array('-'=>'+', '_'=>'/')));
}

Additionally you could remove the trailing padding = characters.

And to get the raw MD5 value (binary string), set the second parameter (named $raw_output in the manual) to true:

$raw_md5 = md5($str, true);