two-factor-authentication / hotp-php-master / hotp.php

hotp.php in Two Factor Authentication 1.2.6, at hotp-php-master/hotp.php

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1	<?php
2	/**
3	* HOTP Class
4	* Based on the work of OAuth, and the sample implementation of HMAC OTP
5	* http://tools.ietf.org/html/draft-mraihi-oath-hmac-otp-04#appendix-D
6	* @author Jakob Heuser (firstname)@felocity.com
7	* @copyright 2011
8	* @license BSD
9	* @version 1.0
10	*/
11	class HOTP {
12	/**
13	* Generate a HOTP key based on a counter value (event based HOTP)
14	* @param string $key the key to use for hashing
15	* @param int $counter the number of attempts represented in this hashing
16	* @return HOTPResult a HOTP Result which can be truncated or output
17	*/
18	public static function generateByCounter($key, $counter) {
19	// the counter value can be more than one byte long,
20	// so we need to pack it down properly.
21	$cur_counter = array(0, 0, 0, 0, 0, 0, 0, 0);
22	for($i = 7; $i >= 0; $i--) {
23	$cur_counter[$i] = pack ('C*', $counter);
24	$counter = $counter >> 8;
25	}
26
27	$bin_counter = implode($cur_counter);
28
29	// Pad to 8 chars
30	if (strlen($bin_counter) < 8) {
31	$bin_counter = str_repeat (chr(0), 8 - strlen ($bin_counter)) . $bin_counter;
32	}
33
34	// HMAC
35	$hash = hash_hmac('sha1', $bin_counter, $key);
36
37	return new HOTPResult($hash);
38	}
39
40	/**
41	* Generate a HOTP key based on a timestamp and window size
42	* @param string $key the key to use for hashing
43	* @param int $window the size of the window a key is valid for in seconds
44	* @param int $timestamp a timestamp to calculate for, defaults to time()
45	* @return HOTPResult a HOTP Result which can be truncated or output
46	*/
47	public static function generateByTime($key, $window, $timestamp = false) {
48	if (!$timestamp && $timestamp !== 0) {
49	$timestamp = HOTP::getTime();
50	}
51
52	$counter = intval($timestamp / $window);
53
54	return HOTP::generateByCounter($key, $counter);
55	}
56
57	/**
58	* Generate a HOTP key collection based on a timestamp and window size
59	* all keys that could exist between a start and end time will be included
60	* in the returned array
61	* @param string $key the key to use for hashing
62	* @param int $window the size of the window a key is valid for in seconds
63	* @param int $min the minimum window to accept before $timestamp
64	* @param int $max the maximum window to accept after $timestamp
65	* @param int $timestamp a timestamp to calculate for, defaults to time()
66	* @return array of HOTPResult
67	*/
68	public static function generateByTimeWindow($key, $window, $min = -1, $max = 1, $timestamp = false) {
69	if (!$timestamp && $timestamp !== 0) {
70	$timestamp = HOTP::getTime();
71	}
72
73	$counter = intval($timestamp / $window);
74	$window = range($min, $max);
75
76	$out = array();
77	for ($i = 0; $i < count($window); $i++) {
78	$shift_counter = $window[$i];
79	$out[$shift_counter] = HOTP::generateByCounter($key, $counter + $shift_counter);
80	}
81
82	return $out;
83	}
84
85	/**
86	* Gets the current time
87	* Ensures we are operating in UTC for the entire framework
88	* Restores the timezone on exit.
89	* @return int the current time
90	*/
91	public static function getTime() {
92	return time(); // PHP's time is always UTC
93	}
94	}
95
96	/**
97	* The HOTPResult Class converts an HOTP item to various forms
98	* Supported formats include hex, decimal, string, and HOTP
99	* @author Jakob Heuser (firstname)@felocity.com
100	*/
101	class HOTPResult {
102	protected $hash;
103	protected $binary;
104	protected $decimal;
105
106	/**
107	* Build an HOTP Result
108	* @param string $value the value to construct with
109	*/
110	public function __construct($value) {
111	// store raw
112	$this->hash = $value;
113	}
114
115	/**
116	* Returns the string version of the HOTP
117	* @return string
118	*/
119	public function toString() {
120	return $this->hash;
121	}
122
123	/**
124	* Returns the hex version of the HOTP
125	* @return string
126	*/
127	public function toHex() {
128	if( !$this->hex )
129	{
130	$this->hex = dechex($this->toDec());
131	}
132	return $this->hex;
133	}
134
135	/**
136	* Returns the decimal version of the HOTP
137	* @return int
138	*/
139	public function toDec() {
140	if( !$this->decimal )
141	{
142	// store calculate decimal
143	$hmac_result = array();
144
145	// Convert to decimal
146	foreach(str_split($this->hash,2) as $hex)
147	{
148	$hmac_result[] = hexdec($hex);
149	}
150
151	$offset = $hmac_result[19] & 0xf;
152
153	$this->decimal = (
154	(($hmac_result[$offset+0] & 0x7f) << 24 ) \|
155	(($hmac_result[$offset+1] & 0xff) << 16 ) \|
156	(($hmac_result[$offset+2] & 0xff) << 8 ) \|
157	($hmac_result[$offset+3] & 0xff)
158	);
159	}
160	return $this->decimal;
161	}
162
163	/**
164	* Returns the truncated decimal form of the HOTP
165	* @param int $length the length of the HOTP to return
166	* @return string
167	*/
168	public function toHOTP($length) {
169	$str = str_pad($this->toDec(), $length, "0", STR_PAD_LEFT);
170	$str = substr($str, (-1 * $length));
171	return $str;
172	}
173
174	}
175