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comparison vendor/pear/auth_sasl/Auth/SASL/SCRAM.php @ 0:1e000243b222

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vanilla 1.3.3 distro, I hope
author Charlie Root
date Thu, 04 Jan 2018 15:50:29 -0500
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1 <?php
2 // +-----------------------------------------------------------------------+
3 // | Copyright (c) 2011 Jehan |
4 // | All rights reserved. |
5 // | |
6 // | Redistribution and use in source and binary forms, with or without |
7 // | modification, are permitted provided that the following conditions |
8 // | are met: |
9 // | |
10 // | o Redistributions of source code must retain the above copyright |
11 // | notice, this list of conditions and the following disclaimer. |
12 // | o Redistributions in binary form must reproduce the above copyright |
13 // | notice, this list of conditions and the following disclaimer in the |
14 // | documentation and/or other materials provided with the distribution.|
15 // | o The names of the authors may not be used to endorse or promote |
16 // | products derived from this software without specific prior written |
17 // | permission. |
18 // | |
19 // | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
20 // | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
21 // | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
22 // | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
23 // | OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
24 // | SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
25 // | LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
26 // | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
27 // | THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
28 // | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
29 // | OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
30 // | |
31 // +-----------------------------------------------------------------------+
32 // | Author: Jehan <jehan.marmottard@gmail.com |
33 // +-----------------------------------------------------------------------+
34 //
35 // $Id$
36
37 /**
38 * Implementation of SCRAM-* SASL mechanisms.
39 * SCRAM mechanisms have 3 main steps (initial response, response to the server challenge, then server signature
40 * verification) which keep state-awareness. Therefore a single class instanciation must be done and reused for the whole
41 * authentication process.
42 *
43 * @author Jehan <jehan.marmottard@gmail.com>
44 * @access public
45 * @version 1.0
46 * @package Auth_SASL
47 */
48
49 require_once('Auth/SASL/Common.php');
50
51 class Auth_SASL_SCRAM extends Auth_SASL_Common
52 {
53 /**
54 * Construct a SCRAM-H client where 'H' is a cryptographic hash function.
55 *
56 * @param string $hash The name cryptographic hash function 'H' as registered by IANA in the "Hash Function Textual
57 * Names" registry.
58 * @link http://www.iana.org/assignments/hash-function-text-names/hash-function-text-names.xml "Hash Function Textual
59 * Names"
60 * format of core PHP hash function.
61 * @access public
62 */
63 function __construct($hash)
64 {
65 // Though I could be strict, I will actually also accept the naming used in the PHP core hash framework.
66 // For instance "sha1" is accepted, while the registered hash name should be "SHA-1".
67 $hash = strtolower($hash);
68 $hashes = array('md2' => 'md2',
69 'md5' => 'md5',
70 'sha-1' => 'sha1',
71 'sha1' => 'sha1',
72 'sha-224' > 'sha224',
73 'sha224' > 'sha224',
74 'sha-256' => 'sha256',
75 'sha256' => 'sha256',
76 'sha-384' => 'sha384',
77 'sha384' => 'sha384',
78 'sha-512' => 'sha512',
79 'sha512' => 'sha512');
80 if (function_exists('hash_hmac') && isset($hashes[$hash]))
81 {
82 $this->hash = create_function('$data', 'return hash("' . $hashes[$hash] . '", $data, TRUE);');
83 $this->hmac = create_function('$key,$str,$raw', 'return hash_hmac("' . $hashes[$hash] . '", $str, $key, $raw);');
84 }
85 elseif ($hash == 'md5')
86 {
87 $this->hash = create_function('$data', 'return md5($data, true);');
88 $this->hmac = array($this, '_HMAC_MD5');
89 }
90 elseif (in_array($hash, array('sha1', 'sha-1')))
91 {
92 $this->hash = create_function('$data', 'return sha1($data, true);');
93 $this->hmac = array($this, '_HMAC_SHA1');
94 }
95 else
96 return PEAR::raiseError('Invalid SASL mechanism type');
97 }
98
99 /**
100 * Provides the (main) client response for SCRAM-H.
101 *
102 * @param string $authcid Authentication id (username)
103 * @param string $pass Password
104 * @param string $challenge The challenge sent by the server.
105 * If the challenge is NULL or an empty string, the result will be the "initial response".
106 * @param string $authzid Authorization id (username to proxy as)
107 * @return string|false The response (binary, NOT base64 encoded)
108 * @access public
109 */
110 public function getResponse($authcid, $pass, $challenge = NULL, $authzid = NULL)
111 {
112 $authcid = $this->_formatName($authcid);
113 if (empty($authcid))
114 {
115 return false;
116 }
117 if (!empty($authzid))
118 {
119 $authzid = $this->_formatName($authzid);
120 if (empty($authzid))
121 {
122 return false;
123 }
124 }
125
126 if (empty($challenge))
127 {
128 return $this->_generateInitialResponse($authcid, $authzid);
129 }
130 else
131 {
132 return $this->_generateResponse($challenge, $pass);
133 }
134
135 }
136
137 /**
138 * Prepare a name for inclusion in a SCRAM response.
139 *
140 * @param string $username a name to be prepared.
141 * @return string the reformated name.
142 * @access private
143 */
144 private function _formatName($username)
145 {
146 // TODO: prepare through the SASLprep profile of the stringprep algorithm.
147 // See RFC-4013.
148
149 $username = str_replace('=', '=3D', $username);
150 $username = str_replace(',', '=2C', $username);
151 return $username;
152 }
153
154 /**
155 * Generate the initial response which can be either sent directly in the first message or as a response to an empty
156 * server challenge.
157 *
158 * @param string $authcid Prepared authentication identity.
159 * @param string $authzid Prepared authorization identity.
160 * @return string The SCRAM response to send.
161 * @access private
162 */
163 private function _generateInitialResponse($authcid, $authzid)
164 {
165 $init_rep = '';
166 $gs2_cbind_flag = 'n,'; // TODO: support channel binding.
167 $this->gs2_header = $gs2_cbind_flag . (!empty($authzid)? 'a=' . $authzid : '') . ',';
168
169 // I must generate a client nonce and "save" it for later comparison on second response.
170 $this->cnonce = $this->_getCnonce();
171 // XXX: in the future, when mandatory and/or optional extensions are defined in any updated RFC,
172 // this message can be updated.
173 $this->first_message_bare = 'n=' . $authcid . ',r=' . $this->cnonce;
174 return $this->gs2_header . $this->first_message_bare;
175 }
176
177 /**
178 * Parses and verifies a non-empty SCRAM challenge.
179 *
180 * @param string $challenge The SCRAM challenge
181 * @return string|false The response to send; false in case of wrong challenge or if an initial response has not
182 * been generated first.
183 * @access private
184 */
185 private function _generateResponse($challenge, $password)
186 {
187 // XXX: as I don't support mandatory extension, I would fail on them.
188 // And I simply ignore any optional extension.
189 $server_message_regexp = "#^r=([\x21-\x2B\x2D-\x7E]+),s=((?:[A-Za-z0-9/+]{4})*(?:[A-Za-z0-9]{3}=|[A-Xa-z0-9]{2}==)?),i=([0-9]*)(,[A-Za-z]=[^,])*$#";
190 if (!isset($this->cnonce, $this->gs2_header)
191 || !preg_match($server_message_regexp, $challenge, $matches))
192 {
193 return false;
194 }
195 $nonce = $matches[1];
196 $salt = base64_decode($matches[2]);
197 if (!$salt)
198 {
199 // Invalid Base64.
200 return false;
201 }
202 $i = intval($matches[3]);
203
204 $cnonce = substr($nonce, 0, strlen($this->cnonce));
205 if ($cnonce <> $this->cnonce)
206 {
207 // Invalid challenge! Are we under attack?
208 return false;
209 }
210
211 $channel_binding = 'c=' . base64_encode($this->gs2_header); // TODO: support channel binding.
212 $final_message = $channel_binding . ',r=' . $nonce; // XXX: no extension.
213
214 // TODO: $password = $this->normalize($password); // SASLprep profile of stringprep.
215 $saltedPassword = $this->hi($password, $salt, $i);
216 $this->saltedPassword = $saltedPassword;
217 $clientKey = call_user_func($this->hmac, $saltedPassword, "Client Key", TRUE);
218 $storedKey = call_user_func($this->hash, $clientKey, TRUE);
219 $authMessage = $this->first_message_bare . ',' . $challenge . ',' . $final_message;
220 $this->authMessage = $authMessage;
221 $clientSignature = call_user_func($this->hmac, $storedKey, $authMessage, TRUE);
222 $clientProof = $clientKey ^ $clientSignature;
223 $proof = ',p=' . base64_encode($clientProof);
224
225 return $final_message . $proof;
226 }
227
228 /**
229 * SCRAM has also a server verification step. On a successful outcome, it will send additional data which must
230 * absolutely be checked against this function. If this fails, the entity which we are communicating with is probably
231 * not the server as it has not access to your ServerKey.
232 *
233 * @param string $data The additional data sent along a successful outcome.
234 * @return bool Whether the server has been authenticated.
235 * If false, the client must close the connection and consider to be under a MITM attack.
236 * @access public
237 */
238 public function processOutcome($data)
239 {
240 $verifier_regexp = '#^v=((?:[A-Za-z0-9/+]{4})*(?:[A-Za-z0-9]{3}=|[A-Xa-z0-9]{2}==)?)$#';
241 if (!isset($this->saltedPassword, $this->authMessage)
242 || !preg_match($verifier_regexp, $data, $matches))
243 {
244 // This cannot be an outcome, you never sent the challenge's response.
245 return false;
246 }
247
248 $verifier = $matches[1];
249 $proposed_serverSignature = base64_decode($verifier);
250 $serverKey = call_user_func($this->hmac, $this->saltedPassword, "Server Key", true);
251 $serverSignature = call_user_func($this->hmac, $serverKey, $this->authMessage, TRUE);
252 return ($proposed_serverSignature === $serverSignature);
253 }
254
255 /**
256 * Hi() call, which is essentially PBKDF2 (RFC-2898) with HMAC-H() as the pseudorandom function.
257 *
258 * @param string $str The string to hash.
259 * @param string $hash The hash value.
260 * @param int $i The iteration count.
261 * @access private
262 */
263 private function hi($str, $salt, $i)
264 {
265 $int1 = "\0\0\0\1";
266 $ui = call_user_func($this->hmac, $str, $salt . $int1, true);
267 $result = $ui;
268 for ($k = 1; $k < $i; $k++)
269 {
270 $ui = call_user_func($this->hmac, $str, $ui, true);
271 $result = $result ^ $ui;
272 }
273 return $result;
274 }
275
276
277 /**
278 * Creates the client nonce for the response
279 *
280 * @return string The cnonce value
281 * @access private
282 * @author Richard Heyes <richard@php.net>
283 */
284 private function _getCnonce()
285 {
286 // TODO: I reused the nonce function from the DigestMD5 class.
287 // I should probably make this a protected function in Common.
288 if (@file_exists('/dev/urandom') && $fd = @fopen('/dev/urandom', 'r')) {
289 return base64_encode(fread($fd, 32));
290
291 } elseif (@file_exists('/dev/random') && $fd = @fopen('/dev/random', 'r')) {
292 return base64_encode(fread($fd, 32));
293
294 } else {
295 $str = '';
296 for ($i=0; $i<32; $i++) {
297 $str .= chr(mt_rand(0, 255));
298 }
299
300 return base64_encode($str);
301 }
302 }
303
304 }
305
306 ?>