base32.php

Go to the documentation of this file.

<?php
class Base32 {
 
    private static $lut = array(
        "A" => 0, "B" => 1,
        "C" => 2, "D" => 3,
        "E" => 4, "F" => 5,
        "G" => 6, "H" => 7,
        "I" => 8, "J" => 9,
        "K" => 10, "L" => 11,
        "M" => 12, "N" => 13,
        "O" => 14, "P" => 15,
        "Q" => 16, "R" => 17,
        "S" => 18, "T" => 19,
        "U" => 20, "V" => 21,
        "W" => 22, "X" => 23,
        "Y" => 24, "Z" => 25,
        "2" => 26, "3" => 27,
        "4" => 28, "5" => 29,
        "6" => 30, "7" => 31
    );
 
    public static function decode($b32) {
 
        $b32 = strtoupper($b32);
 
        if (!preg_match('/^[ABCDEFGHIJKLMNOPQRSTUVWXYZ234567]+$/', $b32, $match))
            throw new Exception('Invalid characters in the base32 string.');
 
        $l      = strlen($b32);
        $n      = 0;
        $j      = 0;
        $binary = "";
 
        for ($i = 0; $i < $l; $i++) {
            // Move buffer left by 5 to make room
            $n = $n << 5;
            // Add value into buffer
            $n = $n + self::$lut[$b32[$i]];
            // Keep track of number of bits in buffer
            $j = $j + 5;
 
            if ($j >= 8) {
                $j = $j - 8;
                $binary .= chr(($n & (0xFF << $j)) >> $j);
            }
        }
 
        return $binary;
    }
 
    public static function encode($string) {
 
        if (empty($string))
            throw new Exception('Empty string.');
 
        $b32 = "";
        $binary = "";
 
        $bytes = str_split($string);
        $length = count( $bytes );
        for ($i = 0; $i < $length; $i++) {
            $bits = base_convert(ord($bytes[$i]), 10, 2);
            $binary .= str_pad($bits, 8, '0', STR_PAD_LEFT);
        }
 
        $map = array_keys(self::$lut);
        $fivebits = str_split($binary, 5);
        $length = count( $fivebits );
        for ($i = 0; $i < $length; $i++) {
            $dec = base_convert(str_pad($fivebits[$i],  5, '0'), 2, 10);
            $b32 .= $map[$dec];
        }
 
        return $b32;
    }
}