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<?php
/**
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* PHP Google two-factor authentication module.
*
* See http://www.idontplaydarts.com/2011/07/google-totp-two-factor-authentication-for-php/
* for more details
*
* @author Phil
**/
class Base32 {
private static $lut = array(
"A" => 0, "B" => 1,
"C" => 2, "D" => 3,
"E" => 4, "F" => 5,
"G" => 6, "H" => 7,
"I" => 8, "J" => 9,
"K" => 10, "L" => 11,
"M" => 12, "N" => 13,
"O" => 14, "P" => 15,
"Q" => 16, "R" => 17,
"S" => 18, "T" => 19,
"U" => 20, "V" => 21,
"W" => 22, "X" => 23,
"Y" => 24, "Z" => 25,
"2" => 26, "3" => 27,
"4" => 28, "5" => 29,
"6" => 30, "7" => 31
);
/**
* Decodes a base32 string into a binary string according to RFC 4648.
**/
public static function decode($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 $binary;
}
/**
* Encodes a binary string into a base32 string according to RFC 4648 (no padding).
**/
public static function encode($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;
}
}
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