Current File : /www/varak.net/wiki.varak.net/extensions/OATHAuth/includes/lib/hotp.php
<?php
/**
* HOTP Class
* Based on the work of OAuth, and the sample implementation of HMAC OTP
* http://tools.ietf.org/html/draft-mraihi-oath-hmac-otp-04#appendix-D
* @author Jakob Heuser (firstname)@felocity.com
* @copyright 2011
* @license BSD-3-Clause
* @version 1.0
*/
class HOTP {
/**
* Generate a HOTP key based on a counter value (event based HOTP)
* @param string $key the key to use for hashing
* @param int $counter the number of attempts represented in this hashing
* @return HOTPResult a HOTP Result which can be truncated or output
*/
public static function generateByCounter( $key, $counter ) {
// the counter value can be more than one byte long,
// so we need to pack it down properly.
$cur_counter = array( 0, 0, 0, 0, 0, 0, 0, 0 );
for ( $i = 7; $i >= 0; $i-- ) {
$cur_counter[$i] = pack( 'C*', $counter );
$counter = $counter >> 8;
}
$bin_counter = implode( $cur_counter );
// Pad to 8 chars
if ( strlen( $bin_counter ) < 8 ) {
$bin_counter = str_repeat( "\0", 8 - strlen( $bin_counter ) ) . $bin_counter;
}
// HMAC
$hash = hash_hmac( 'sha1', $bin_counter, $key );
return new HOTPResult( $hash );
}
/**
* Generate a HOTP key based on a timestamp and window size
*
* @param string $key the key to use for hashing
* @param int $window the size of the window a key is valid for in seconds
* @param int|bool $timestamp a timestamp to calculate for, defaults to time()
*
* @return HOTPResult a HOTP Result which can be truncated or output
*/
public static function generateByTime( $key, $window, $timestamp = false ) {
if ( !$timestamp && $timestamp !== 0 ) {
$timestamp = HOTP::getTime();
}
$counter = (int)( $timestamp / $window );
return HOTP::generateByCounter( $key, $counter );
}
/**
* Generate a HOTP key collection based on a timestamp and window size
* all keys that could exist between a start and end time will be included
* in the returned array
*
* @param string $key the key to use for hashing
* @param int $window the size of the window a key is valid for in seconds
* @param int $min the minimum window to accept before $timestamp
* @param int $max the maximum window to accept after $timestamp
* @param int|bool $timestamp a timestamp to calculate for, defaults to time()
*
* @return HOTPResult[]
*/
public static function generateByTimeWindow( $key, $window, $min = -1,
$max = 1, $timestamp = false
) {
if ( !$timestamp && $timestamp !== 0 ) {
$timestamp = HOTP::getTime();
}
$counter = (int)( $timestamp / $window );
$window = range( $min, $max );
$out = array();
$length = count( $window );
for ( $i = 0; $i < $length; $i++ ) {
$shift_counter = $counter + $window[$i];
$out[$shift_counter] = HOTP::generateByCounter($key, $shift_counter);
}
return $out;
}
/**
* Gets the current time
* Ensures we are operating in UTC for the entire framework
* Restores the timezone on exit.
* @return int the current time
*/
public static function getTime() {
return time(); // PHP's time is always UTC
}
}
/**
* The HOTPResult Class converts an HOTP item to various forms
* Supported formats include hex, decimal, string, and HOTP
* @author Jakob Heuser (firstname)@felocity.com
*/
class HOTPResult {
protected $hash;
protected $binary;
protected $decimal;
protected $hex;
/**
* Build an HOTP Result
* @param string $value the value to construct with
*/
public function __construct( $value ) {
// store raw
$this->hash = $value;
// store calculate decimal
$hmac_result = array();
// Convert to decimal
foreach ( str_split( $this->hash, 2 ) as $hex ) {
$hmac_result[] = hexdec($hex);
}
$offset = $hmac_result[19] & 0xf;
$this->decimal = (
( ( $hmac_result[$offset+0] & 0x7f ) << 24 ) |
( ( $hmac_result[$offset+1] & 0xff ) << 16 ) |
( ( $hmac_result[$offset+2] & 0xff ) << 8 ) |
( $hmac_result[$offset+3] & 0xff )
);
// calculate hex
$this->hex = dechex( $this->decimal );
}
/**
* Returns the string version of the HOTP
* @return string
*/
public function toString() {
return $this->hash;
}
/**
* Returns the hex version of the HOTP
* @return string
*/
public function toHex() {
return $this->hex;
}
/**
* Returns the decimal version of the HOTP
* @return int
*/
public function toDec() {
return $this->decimal;
}
/**
* Returns the truncated decimal form of the HOTP
* @param int $length the length of the HOTP to return
* @return string
*/
public function toHOTP( $length ) {
$str = str_pad( $this->toDec(), $length, "0", STR_PAD_LEFT );
$str = substr( $str, ( -1 * $length ) );
return $str;
}
}
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