MWCryptRand.php

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<?php
class MWCryptRand {
 
    public static function generateHex( $chars ) {
        // hex strings are 2x the length of raw binary so we divide the length in half
        // odd numbers will result in a .5 that leads the generate() being 1 character
        // short, so we use ceil() to ensure that we always have enough bytes
        $bytes = ceil( $chars / 2 );
        // Generate the data and then convert it to a hex string
        $hex = bin2hex( random_bytes( $bytes ) );
 
        // A bit of paranoia here, the caller asked for a specific length of string
        // here, and it's possible (eg when given an odd number) that we may actually
        // have at least 1 char more than they asked for. Just in case they made this
        // call intending to insert it into a database that does truncation we don't
        // want to give them too much and end up with their database and their live
        // code having two different values because part of what we gave them is truncated
        // hence, we strip out any run of characters longer than what we were asked for.
        return substr( $hex, 0, $chars );
    }
}