mirror of
https://github.com/prasathmani/tinyfilemanager
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165 lines
4.3 KiB
PHP
165 lines
4.3 KiB
PHP
<?php
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/**
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* PHP Google two-factor authentication module.
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*
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* See https://www.idontplaydarts.com/2011/07/google-totp-two-factor-authentication-for-php/
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* for more details
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*
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* @author Phil
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**/
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class Google2FA {
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const keyRegeneration = 30; // Interval between key regeneration
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const otpLength = 6; // Length of the Token generated
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private static $lut = array( // Lookup needed for Base32 encoding
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"A" => 0, "B" => 1,
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"C" => 2, "D" => 3,
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"E" => 4, "F" => 5,
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"G" => 6, "H" => 7,
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"I" => 8, "J" => 9,
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"K" => 10, "L" => 11,
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"M" => 12, "N" => 13,
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"O" => 14, "P" => 15,
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"Q" => 16, "R" => 17,
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"S" => 18, "T" => 19,
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"U" => 20, "V" => 21,
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"W" => 22, "X" => 23,
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"Y" => 24, "Z" => 25,
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"2" => 26, "3" => 27,
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"4" => 28, "5" => 29,
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"6" => 30, "7" => 31
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);
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/**
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* Generates a 16 digit secret key in base32 format
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* @return string
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**/
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public static function generate_secret_key($length = 16) {
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$b32 = "234567QWERTYUIOPASDFGHJKLZXCVBNM";
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$s = "";
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for ($i = 0; $i < $length; $i++)
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$s .= $b32[rand(0,31)];
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return $s;
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}
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/**
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* Returns the current Unix Timestamp divided by the keyRegeneration
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* period.
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* @return integer
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**/
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public static function get_timestamp() {
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return floor(microtime(true)/self::keyRegeneration);
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}
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/**
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* Decodes a base32 string into a binary string.
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**/
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public static function base32_decode($b32) {
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$b32 = strtoupper($b32);
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if (!preg_match('/^[ABCDEFGHIJKLMNOPQRSTUVWXYZ234567]+$/', $b32, $match))
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throw new Exception('Invalid characters in the base32 string.');
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$l = strlen($b32);
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$n = 0;
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$j = 0;
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$binary = "";
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for ($i = 0; $i < $l; $i++) {
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$n = $n << 5; // Move buffer left by 5 to make room
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$n = $n + self::$lut[$b32[$i]]; // Add value into buffer
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$j = $j + 5; // Keep track of number of bits in buffer
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if ($j >= 8) {
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$j = $j - 8;
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$binary .= chr(($n & (0xFF << $j)) >> $j);
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}
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}
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return $binary;
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}
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/**
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* Takes the secret key and the timestamp and returns the one time
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* password.
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*
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* @param binary $key - Secret key in binary form.
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* @param integer $counter - Timestamp as returned by get_timestamp.
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* @return string
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**/
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public static function oath_hotp($key, $counter)
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{
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if (strlen($key) < 8)
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throw new Exception('Secret key is too short. Must be at least 16 base 32 characters');
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$bin_counter = pack('N*', 0) . pack('N*', $counter); // Counter must be 64-bit int
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$hash = hash_hmac ('sha1', $bin_counter, $key, true);
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return str_pad(self::oath_truncate($hash), self::otpLength, '0', STR_PAD_LEFT);
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}
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/**
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* Verifys a user inputted key against the current timestamp. Checks $window
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* keys either side of the timestamp.
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*
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* @param string $b32seed
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* @param string $key - User specified key
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* @param integer $window
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* @param boolean $useTimeStamp
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* @return boolean
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**/
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public static function verify_key($b32seed, $key, $window = 0, $useTimeStamp = true) {
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$timeStamp = self::get_timestamp();
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if ($useTimeStamp !== true) $timeStamp = (int)$useTimeStamp;
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$binarySeed = self::base32_decode($b32seed);
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for ($ts = $timeStamp - $window; $ts <= $timeStamp + $window; $ts++)
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if (self::oath_hotp($binarySeed, $ts) == $key)
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return true;
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return false;
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}
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/**
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* Extracts the OTP from the SHA1 hash.
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* @param binary $hash
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* @return integer
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**/
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public static function oath_truncate($hash)
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{
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$offset = ord($hash[19]) & 0xf;
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return (
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((ord($hash[$offset+0]) & 0x7f) << 24 ) |
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((ord($hash[$offset+1]) & 0xff) << 16 ) |
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((ord($hash[$offset+2]) & 0xff) << 8 ) |
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(ord($hash[$offset+3]) & 0xff)
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) % pow(10, self::otpLength);
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}
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}
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?>
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