1: <?php
  2: /**
  3:  * Core Security
  4:  *
  5:  * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
  6:  * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
  7:  *
  8:  * Licensed under The MIT License
  9:  * For full copyright and license information, please see the LICENSE.txt
 10:  * Redistributions of files must retain the above copyright notice.
 11:  *
 12:  * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 13:  * @link          http://cakephp.org CakePHP(tm) Project
 14:  * @package       Cake.Utility
 15:  * @since         CakePHP(tm) v .0.10.0.1233
 16:  * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 17:  */
 18: 
 19: App::uses('CakeText', 'Utility');
 20: 
 21: /**
 22:  * Security Library contains utility methods related to security
 23:  *
 24:  * @package       Cake.Utility
 25:  */
 26: class Security {
 27: 
 28: /**
 29:  * Default hash method
 30:  *
 31:  * @var string
 32:  */
 33:     public static $hashType = null;
 34: 
 35: /**
 36:  * Default cost
 37:  *
 38:  * @var string
 39:  */
 40:     public static $hashCost = '10';
 41: 
 42: /**
 43:  * Get allowed minutes of inactivity based on security level.
 44:  *
 45:  * @deprecated 3.0.0 Exists for backwards compatibility only, not used by the core
 46:  * @return int Allowed inactivity in minutes
 47:  */
 48:     public static function inactiveMins() {
 49:         switch (Configure::read('Security.level')) {
 50:             case 'high':
 51:                 return 10;
 52:             case 'medium':
 53:                 return 100;
 54:             case 'low':
 55:             default:
 56:                 return 300;
 57:         }
 58:     }
 59: 
 60: /**
 61:  * Generate authorization hash.
 62:  *
 63:  * @return string Hash
 64:  * @deprecated 2.8.1 This method was removed in 3.0.0
 65:  */
 66:     public static function generateAuthKey() {
 67:         return Security::hash(CakeText::uuid());
 68:     }
 69: 
 70: /**
 71:  * Validate authorization hash.
 72:  *
 73:  * @param string $authKey Authorization hash
 74:  * @return bool Success
 75:  * @deprecated 2.8.1 This method was removed in 3.0.0
 76:  */
 77:     public static function validateAuthKey($authKey) {
 78:         return true;
 79:     }
 80: 
 81: /**
 82:  * Create a hash from string using given method or fallback on next available method.
 83:  *
 84:  * #### Using Blowfish
 85:  *
 86:  * - Creating Hashes: *Do not supply a salt*. Cake handles salt creation for
 87:  * you ensuring that each hashed password will have a *unique* salt.
 88:  * - Comparing Hashes: Simply pass the originally hashed password as the salt.
 89:  * The salt is prepended to the hash and php handles the parsing automagically.
 90:  * For convenience the `BlowfishPasswordHasher` class is available for use with
 91:  * the AuthComponent.
 92:  * - Do NOT use a constant salt for blowfish!
 93:  *
 94:  * Creating a blowfish/bcrypt hash:
 95:  *
 96:  * ```
 97:  * $hash = Security::hash($password, 'blowfish');
 98:  * ```
 99:  *
100:  * @param string $string String to hash
101:  * @param string $type Method to use (sha1/sha256/md5/blowfish)
102:  * @param mixed $salt If true, automatically prepends the application's salt
103:  *     value to $string (Security.salt). If you are using blowfish the salt
104:  *     must be false or a previously generated salt.
105:  * @return string Hash
106:  * @link http://book.cakephp.org/2.0/en/core-utility-libraries/security.html#Security::hash
107:  */
108:     public static function hash($string, $type = null, $salt = false) {
109:         if (empty($type)) {
110:             $type = static::$hashType;
111:         }
112:         $type = strtolower($type);
113: 
114:         if ($type === 'blowfish') {
115:             return static::_crypt($string, $salt);
116:         }
117:         if ($salt) {
118:             if (!is_string($salt)) {
119:                 $salt = Configure::read('Security.salt');
120:             }
121:             $string = $salt . $string;
122:         }
123: 
124:         if (!$type || $type === 'sha1') {
125:             if (function_exists('sha1')) {
126:                 return sha1($string);
127:             }
128:             $type = 'sha256';
129:         }
130: 
131:         if ($type === 'sha256' && function_exists('mhash')) {
132:             return bin2hex(mhash(MHASH_SHA256, $string));
133:         }
134: 
135:         if (function_exists('hash')) {
136:             return hash($type, $string);
137:         }
138:         return md5($string);
139:     }
140: 
141: /**
142:  * Sets the default hash method for the Security object. This affects all objects using
143:  * Security::hash().
144:  *
145:  * @param string $hash Method to use (sha1/sha256/md5/blowfish)
146:  * @return void
147:  * @see Security::hash()
148:  */
149:     public static function setHash($hash) {
150:         static::$hashType = $hash;
151:     }
152: 
153: /**
154:  * Sets the cost for they blowfish hash method.
155:  *
156:  * @param int $cost Valid values are 4-31
157:  * @return void
158:  */
159:     public static function setCost($cost) {
160:         if ($cost < 4 || $cost > 31) {
161:             trigger_error(__d(
162:                 'cake_dev',
163:                 'Invalid value, cost must be between %s and %s',
164:                 array(4, 31)
165:             ), E_USER_WARNING);
166:             return null;
167:         }
168:         static::$hashCost = $cost;
169:     }
170: 
171: /**
172:  * Get random bytes from a secure source.
173:  *
174:  * This method will fall back to an insecure source and trigger a warning,
175:  * if it cannot find a secure source of random data.
176:  *
177:  * @param int $length The number of bytes you want.
178:  * @return string Random bytes in binary.
179:  */
180:     public static function randomBytes($length) {
181:         if (function_exists('random_bytes')) {
182:             return random_bytes($length);
183:         }
184:         if (function_exists('openssl_random_pseudo_bytes')) {
185:             return openssl_random_pseudo_bytes($length);
186:         }
187:         trigger_error(
188:             'You do not have a safe source of random data available. ' .
189:             'Install either the openssl extension, or paragonie/random_compat. ' .
190:             'Falling back to an insecure random source.',
191:             E_USER_WARNING
192:         );
193:         $bytes = '';
194:         $byteLength = 0;
195:         while ($byteLength < $length) {
196:             $bytes .= static::hash(CakeText::uuid() . uniqid(mt_rand(), true), 'sha512', true);
197:             $byteLength = strlen($bytes);
198:         }
199:         return substr($bytes, 0, $length);
200:     }
201: 
202: /**
203:  * Runs $text through a XOR cipher.
204:  *
205:  * *Note* This is not a cryptographically strong method and should not be used
206:  * for sensitive data. Additionally this method does *not* work in environments
207:  * where suhosin is enabled.
208:  *
209:  * Instead you should use Security::rijndael() when you need strong
210:  * encryption.
211:  *
212:  * @param string $text Encrypted string to decrypt, normal string to encrypt
213:  * @param string $key Key to use
214:  * @return string Encrypted/Decrypted string
215:  * @deprecated 3.0.0 Will be removed in 3.0.
216:  */
217:     public static function cipher($text, $key) {
218:         if (empty($key)) {
219:             trigger_error(__d('cake_dev', 'You cannot use an empty key for %s', 'Security::cipher()'), E_USER_WARNING);
220:             return '';
221:         }
222: 
223:         srand((int)Configure::read('Security.cipherSeed'));
224:         $out = '';
225:         $keyLength = strlen($key);
226:         for ($i = 0, $textLength = strlen($text); $i < $textLength; $i++) {
227:             $j = ord(substr($key, $i % $keyLength, 1));
228:             while ($j--) {
229:                 rand(0, 255);
230:             }
231:             $mask = rand(0, 255);
232:             $out .= chr(ord(substr($text, $i, 1)) ^ $mask);
233:         }
234:         srand();
235:         return $out;
236:     }
237: 
238: /**
239:  * Encrypts/Decrypts a text using the given key using rijndael method.
240:  *
241:  * Prior to 2.3.1, a fixed initialization vector was used. This was not
242:  * secure. This method now uses a random iv, and will silently upgrade values when
243:  * they are re-encrypted.
244:  *
245:  * @param string $text Encrypted string to decrypt, normal string to encrypt
246:  * @param string $key Key to use as the encryption key for encrypted data.
247:  * @param string $operation Operation to perform, encrypt or decrypt
248:  * @return string Encrypted/Decrypted string
249:  */
250:     public static function rijndael($text, $key, $operation) {
251:         if (empty($key)) {
252:             trigger_error(__d('cake_dev', 'You cannot use an empty key for %s', 'Security::rijndael()'), E_USER_WARNING);
253:             return '';
254:         }
255:         if (empty($operation) || !in_array($operation, array('encrypt', 'decrypt'))) {
256:             trigger_error(__d('cake_dev', 'You must specify the operation for Security::rijndael(), either encrypt or decrypt'), E_USER_WARNING);
257:             return '';
258:         }
259:         if (strlen($key) < 32) {
260:             trigger_error(__d('cake_dev', 'You must use a key larger than 32 bytes for Security::rijndael()'), E_USER_WARNING);
261:             return '';
262:         }
263:         $algorithm = MCRYPT_RIJNDAEL_256;
264:         $mode = MCRYPT_MODE_CBC;
265:         $ivSize = mcrypt_get_iv_size($algorithm, $mode);
266: 
267:         $cryptKey = substr($key, 0, 32);
268: 
269:         if ($operation === 'encrypt') {
270:             $iv = mcrypt_create_iv($ivSize, MCRYPT_RAND);
271:             return $iv . '$$' . mcrypt_encrypt($algorithm, $cryptKey, $text, $mode, $iv);
272:         }
273:         // Backwards compatible decrypt with fixed iv
274:         if (substr($text, $ivSize, 2) !== '$$') {
275:             $iv = substr($key, strlen($key) - 32, 32);
276:             return rtrim(mcrypt_decrypt($algorithm, $cryptKey, $text, $mode, $iv), "\0");
277:         }
278:         $iv = substr($text, 0, $ivSize);
279:         $text = substr($text, $ivSize + 2);
280:         return rtrim(mcrypt_decrypt($algorithm, $cryptKey, $text, $mode, $iv), "\0");
281:     }
282: 
283: /**
284:  * Generates a pseudo random salt suitable for use with php's crypt() function.
285:  * The salt length should not exceed 27. The salt will be composed of
286:  * [./0-9A-Za-z]{$length}.
287:  *
288:  * @param int $length The length of the returned salt
289:  * @return string The generated salt
290:  */
291:     protected static function _salt($length = 22) {
292:         $salt = str_replace(
293:             array('+', '='),
294:             '.',
295:             base64_encode(sha1(uniqid(Configure::read('Security.salt'), true), true))
296:         );
297:         return substr($salt, 0, $length);
298:     }
299: 
300: /**
301:  * One way encryption using php's crypt() function. To use blowfish hashing see ``Security::hash()``
302:  *
303:  * @param string $password The string to be encrypted.
304:  * @param mixed $salt false to generate a new salt or an existing salt.
305:  * @return string The hashed string or an empty string on error.
306:  */
307:     protected static function _crypt($password, $salt = false) {
308:         if ($salt === false || $salt === null || $salt === '') {
309:             $salt = static::_salt(22);
310:             $salt = vsprintf('$2a$%02d$%s', array(static::$hashCost, $salt));
311:         }
312: 
313:         $invalidCipher = (
314:             strpos($salt, '$2y$') !== 0 &&
315:             strpos($salt, '$2x$') !== 0 &&
316:             strpos($salt, '$2a$') !== 0
317:         );
318:         if ($salt === true || $invalidCipher || strlen($salt) < 29) {
319:             trigger_error(__d(
320:                 'cake_dev',
321:                 'Invalid salt: %s for %s Please visit http://www.php.net/crypt and read the appropriate section for building %s salts.',
322:                 array($salt, 'blowfish', 'blowfish')
323:             ), E_USER_WARNING);
324:             return '';
325:         }
326:         return crypt($password, $salt);
327:     }
328: 
329: /**
330:  * Encrypt a value using AES-256.
331:  *
332:  * *Caveat* You cannot properly encrypt/decrypt data with trailing null bytes.
333:  * Any trailing null bytes will be removed on decryption due to how PHP pads messages
334:  * with nulls prior to encryption.
335:  *
336:  * @param string $plain The value to encrypt.
337:  * @param string $key The 256 bit/32 byte key to use as a cipher key.
338:  * @param string $hmacSalt The salt to use for the HMAC process. Leave null to use Security.salt.
339:  * @return string Encrypted data.
340:  * @throws CakeException On invalid data or key.
341:  */
342:     public static function encrypt($plain, $key, $hmacSalt = null) {
343:         static::_checkKey($key, 'encrypt()');
344: 
345:         if ($hmacSalt === null) {
346:             $hmacSalt = Configure::read('Security.salt');
347:         }
348: 
349:         // Generate the encryption and hmac key.
350:         $key = substr(hash('sha256', $key . $hmacSalt), 0, 32);
351: 
352:         $algorithm = MCRYPT_RIJNDAEL_128;
353:         $mode = MCRYPT_MODE_CBC;
354: 
355:         $ivSize = mcrypt_get_iv_size($algorithm, $mode);
356:         $iv = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM);
357:         $ciphertext = $iv . mcrypt_encrypt($algorithm, $key, $plain, $mode, $iv);
358:         $hmac = hash_hmac('sha256', $ciphertext, $key);
359:         return $hmac . $ciphertext;
360:     }
361: 
362: /**
363:  * Check the encryption key for proper length.
364:  *
365:  * @param string $key Key to check.
366:  * @param string $method The method the key is being checked for.
367:  * @return void
368:  * @throws CakeException When key length is not 256 bit/32 bytes
369:  */
370:     protected static function _checkKey($key, $method) {
371:         if (strlen($key) < 32) {
372:             throw new CakeException(__d('cake_dev', 'Invalid key for %s, key must be at least 256 bits (32 bytes) long.', $method));
373:         }
374:     }
375: 
376: /**
377:  * Decrypt a value using AES-256.
378:  *
379:  * @param string $cipher The ciphertext to decrypt.
380:  * @param string $key The 256 bit/32 byte key to use as a cipher key.
381:  * @param string $hmacSalt The salt to use for the HMAC process. Leave null to use Security.salt.
382:  * @return string Decrypted data. Any trailing null bytes will be removed.
383:  * @throws CakeException On invalid data or key.
384:  */
385:     public static function decrypt($cipher, $key, $hmacSalt = null) {
386:         static::_checkKey($key, 'decrypt()');
387:         if (empty($cipher)) {
388:             throw new CakeException(__d('cake_dev', 'The data to decrypt cannot be empty.'));
389:         }
390:         if ($hmacSalt === null) {
391:             $hmacSalt = Configure::read('Security.salt');
392:         }
393: 
394:         // Generate the encryption and hmac key.
395:         $key = substr(hash('sha256', $key . $hmacSalt), 0, 32);
396: 
397:         // Split out hmac for comparison
398:         $macSize = 64;
399:         $hmac = substr($cipher, 0, $macSize);
400:         $cipher = substr($cipher, $macSize);
401: 
402:         $compareHmac = hash_hmac('sha256', $cipher, $key);
403:         if ($hmac !== $compareHmac) {
404:             return false;
405:         }
406: 
407:         $algorithm = MCRYPT_RIJNDAEL_128;
408:         $mode = MCRYPT_MODE_CBC;
409:         $ivSize = mcrypt_get_iv_size($algorithm, $mode);
410: 
411:         $iv = substr($cipher, 0, $ivSize);
412:         $cipher = substr($cipher, $ivSize);
413:         $plain = mcrypt_decrypt($algorithm, $key, $cipher, $mode, $iv);
414:         return rtrim($plain, "\0");
415:     }
416: 
417: }
418: