<?php 

    function rand_alphanumeric() {



        $subsets[0] = array('min' => 48, 'max' => 57); // ascii digits

        $subsets[1] = array('min' => 65, 'max' => 90); // ascii uppercase English letters

        $subsets[2] = array('min' => 97, 'max' => 122); // ascii lowercase English letters 



        // random choice between lowercase, uppercase, and digits

        $s = rand(0, 2);

        $ascii_code = rand($subsets[$s]['min'], $subsets[$s]['max']);

        return chr($ascii_code);

    }

    

    function generate_token($SECRET) {

        $str = "";

        for ($i = 0; $i < 8; $i++) 

            $str .= Self::rand_alphanumeric();

        return $str . strtoupper(sha1($str . $SECRET));

    }



    function validate_token($TOKEN, $SECRET) {

        $str = substr($TOKEN, 0, 8);



        if ($TOKEN === ($str . strtoupper(sha1($str . $SECRET))))

            return true;

        return false;

    }