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Add lost file from Auth_SASL package

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alecpl committed Jul 30, 2012
1 parent 750fcf8 commit e9c8b9865ff53bcb1a7346569079eacc15c919b7
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  1. +306 −0 program/lib/Auth/SASL/SCRAM.php
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+<?php
+// +-----------------------------------------------------------------------+
+// | Copyright (c) 2011 Jehan |
+// | All rights reserved. |
+// | |
+// | Redistribution and use in source and binary forms, with or without |
+// | modification, are permitted provided that the following conditions |
+// | are met: |
+// | |
+// | o Redistributions of source code must retain the above copyright |
+// | notice, this list of conditions and the following disclaimer. |
+// | o Redistributions in binary form must reproduce the above copyright |
+// | notice, this list of conditions and the following disclaimer in the |
+// | documentation and/or other materials provided with the distribution.|
+// | o The names of the authors may not be used to endorse or promote |
+// | products derived from this software without specific prior written |
+// | permission. |
+// | |
+// | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
+// | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
+// | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
+// | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
+// | OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
+// | SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
+// | LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
+// | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
+// | THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
+// | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
+// | OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
+// | |
+// +-----------------------------------------------------------------------+
+// | Author: Jehan <jehan.marmottard@gmail.com |
+// +-----------------------------------------------------------------------+
+//
+// $Id$
+
+/**
+* Implementation of SCRAM-* SASL mechanisms.
+* SCRAM mechanisms have 3 main steps (initial response, response to the server challenge, then server signature
+* verification) which keep state-awareness. Therefore a single class instanciation must be done and reused for the whole
+* authentication process.
+*
+* @author Jehan <jehan.marmottard@gmail.com>
+* @access public
+* @version 1.0
+* @package Auth_SASL
+*/
+
+require_once('Auth/SASL/Common.php');
+
+class Auth_SASL_SCRAM extends Auth_SASL_Common
+{
+ /**
+ * Construct a SCRAM-H client where 'H' is a cryptographic hash function.
+ *
+ * @param string $hash The name cryptographic hash function 'H' as registered by IANA in the "Hash Function Textual
+ * Names" registry.
+ * @link http://www.iana.org/assignments/hash-function-text-names/hash-function-text-names.xml "Hash Function Textual
+ * Names"
+ * format of core PHP hash function.
+ * @access public
+ */
+ function __construct($hash)
+ {
+ // Though I could be strict, I will actually also accept the naming used in the PHP core hash framework.
+ // For instance "sha1" is accepted, while the registered hash name should be "SHA-1".
+ $hash = strtolower($hash);
+ $hashes = array('md2' => 'md2',
+ 'md5' => 'md5',
+ 'sha-1' => 'sha1',
+ 'sha1' => 'sha1',
+ 'sha-224' > 'sha224',
+ 'sha224' > 'sha224',
+ 'sha-256' => 'sha256',
+ 'sha256' => 'sha256',
+ 'sha-384' => 'sha384',
+ 'sha384' => 'sha384',
+ 'sha-512' => 'sha512',
+ 'sha512' => 'sha512');
+ if (function_exists('hash_hmac') && isset($hashes[$hash]))
+ {
+ $this->hash = create_function('$data', 'return hash("' . $hashes[$hash] . '", $data, TRUE);');
+ $this->hmac = create_function('$key,$str,$raw', 'return hash_hmac("' . $hashes[$hash] . '", $str, $key, $raw);');
+ }
+ elseif ($hash == 'md5')
+ {
+ $this->hash = create_function('$data', 'return md5($data, true);');
+ $this->hmac = array($this, '_HMAC_MD5');
+ }
+ elseif (in_array($hash, array('sha1', 'sha-1')))
+ {
+ $this->hash = create_function('$data', 'return sha1($data, true);');
+ $this->hmac = array($this, '_HMAC_SHA1');
+ }
+ else
+ return PEAR::raiseError('Invalid SASL mechanism type');
+ }
+
+ /**
+ * Provides the (main) client response for SCRAM-H.
+ *
+ * @param string $authcid Authentication id (username)
+ * @param string $pass Password
+ * @param string $challenge The challenge sent by the server.
+ * If the challenge is NULL or an empty string, the result will be the "initial response".
+ * @param string $authzid Authorization id (username to proxy as)
+ * @return string|false The response (binary, NOT base64 encoded)
+ * @access public
+ */
+ public function getResponse($authcid, $pass, $challenge = NULL, $authzid = NULL)
+ {
+ $authcid = $this->_formatName($authcid);
+ if (empty($authcid))
+ {
+ return false;
+ }
+ if (!empty($authzid))
+ {
+ $authzid = $this->_formatName($authzid);
+ if (empty($authzid))
+ {
+ return false;
+ }
+ }
+
+ if (empty($challenge))
+ {
+ return $this->_generateInitialResponse($authcid, $authzid);
+ }
+ else
+ {
+ return $this->_generateResponse($challenge, $pass);
+ }
+
+ }
+
+ /**
+ * Prepare a name for inclusion in a SCRAM response.
+ *
+ * @param string $username a name to be prepared.
+ * @return string the reformated name.
+ * @access private
+ */
+ private function _formatName($username)
+ {
+ // TODO: prepare through the SASLprep profile of the stringprep algorithm.
+ // See RFC-4013.
+
+ $username = str_replace('=', '=3D', $username);
+ $username = str_replace(',', '=2C', $username);
+ return $username;
+ }
+
+ /**
+ * Generate the initial response which can be either sent directly in the first message or as a response to an empty
+ * server challenge.
+ *
+ * @param string $authcid Prepared authentication identity.
+ * @param string $authzid Prepared authorization identity.
+ * @return string The SCRAM response to send.
+ * @access private
+ */
+ private function _generateInitialResponse($authcid, $authzid)
+ {
+ $init_rep = '';
+ $gs2_cbind_flag = 'n,'; // TODO: support channel binding.
+ $this->gs2_header = $gs2_cbind_flag . (!empty($authzid)? 'a=' . $authzid : '') . ',';
+
+ // I must generate a client nonce and "save" it for later comparison on second response.
+ $this->cnonce = $this->_getCnonce();
+ // XXX: in the future, when mandatory and/or optional extensions are defined in any updated RFC,
+ // this message can be updated.
+ $this->first_message_bare = 'n=' . $authcid . ',r=' . $this->cnonce;
+ return $this->gs2_header . $this->first_message_bare;
+ }
+
+ /**
+ * Parses and verifies a non-empty SCRAM challenge.
+ *
+ * @param string $challenge The SCRAM challenge
+ * @return string|false The response to send; false in case of wrong challenge or if an initial response has not
+ * been generated first.
+ * @access private
+ */
+ private function _generateResponse($challenge, $password)
+ {
+ // XXX: as I don't support mandatory extension, I would fail on them.
+ // And I simply ignore any optional extension.
+ $server_message_regexp = "#^r=([\x21-\x2B\x2D-\x7E]+),s=((?:[A-Za-z0-9/+]{4})*(?:[A-Za-z0-9]{3}=|[A-Xa-z0-9]{2}==)?),i=([0-9]*)(,[A-Za-z]=[^,])*$#";
+ if (!isset($this->cnonce, $this->gs2_header)
+ || !preg_match($server_message_regexp, $challenge, $matches))
+ {
+ return false;
+ }
+ $nonce = $matches[1];
+ $salt = base64_decode($matches[2]);
+ if (!$salt)
+ {
+ // Invalid Base64.
+ return false;
+ }
+ $i = intval($matches[3]);
+
+ $cnonce = substr($nonce, 0, strlen($this->cnonce));
+ if ($cnonce <> $this->cnonce)
+ {
+ // Invalid challenge! Are we under attack?
+ return false;
+ }
+
+ $channel_binding = 'c=' . base64_encode($this->gs2_header); // TODO: support channel binding.
+ $final_message = $channel_binding . ',r=' . $nonce; // XXX: no extension.
+
+ // TODO: $password = $this->normalize($password); // SASLprep profile of stringprep.
+ $saltedPassword = $this->hi($password, $salt, $i);
+ $this->saltedPassword = $saltedPassword;
+ $clientKey = call_user_func($this->hmac, $saltedPassword, "Client Key", TRUE);
+ $storedKey = call_user_func($this->hash, $clientKey, TRUE);
+ $authMessage = $this->first_message_bare . ',' . $challenge . ',' . $final_message;
+ $this->authMessage = $authMessage;
+ $clientSignature = call_user_func($this->hmac, $storedKey, $authMessage, TRUE);
+ $clientProof = $clientKey ^ $clientSignature;
+ $proof = ',p=' . base64_encode($clientProof);
+
+ return $final_message . $proof;
+ }
+
+ /**
+ * SCRAM has also a server verification step. On a successful outcome, it will send additional data which must
+ * absolutely be checked against this function. If this fails, the entity which we are communicating with is probably
+ * not the server as it has not access to your ServerKey.
+ *
+ * @param string $data The additional data sent along a successful outcome.
+ * @return bool Whether the server has been authenticated.
+ * If false, the client must close the connection and consider to be under a MITM attack.
+ * @access public
+ */
+ public function processOutcome($data)
+ {
+ $verifier_regexp = '#^v=((?:[A-Za-z0-9/+]{4})*(?:[A-Za-z0-9]{3}=|[A-Xa-z0-9]{2}==)?)$#';
+ if (!isset($this->saltedPassword, $this->authMessage)
+ || !preg_match($verifier_regexp, $data, $matches))
+ {
+ // This cannot be an outcome, you never sent the challenge's response.
+ return false;
+ }
+
+ $verifier = $matches[1];
+ $proposed_serverSignature = base64_decode($verifier);
+ $serverKey = call_user_func($this->hmac, $this->saltedPassword, "Server Key", true);
+ $serverSignature = call_user_func($this->hmac, $serverKey, $this->authMessage, TRUE);
+ return ($proposed_serverSignature === $serverSignature);
+ }
+
+ /**
+ * Hi() call, which is essentially PBKDF2 (RFC-2898) with HMAC-H() as the pseudorandom function.
+ *
+ * @param string $str The string to hash.
+ * @param string $hash The hash value.
+ * @param int $i The iteration count.
+ * @access private
+ */
+ private function hi($str, $salt, $i)
+ {
+ $int1 = "\0\0\0\1";
+ $ui = call_user_func($this->hmac, $str, $salt . $int1, true);
+ $result = $ui;
+ for ($k = 1; $k < $i; $k++)
+ {
+ $ui = call_user_func($this->hmac, $str, $ui, true);
+ $result = $result ^ $ui;
+ }
+ return $result;
+ }
+
+
+ /**
+ * Creates the client nonce for the response
+ *
+ * @return string The cnonce value
+ * @access private
+ * @author Richard Heyes <richard@php.net>
+ */
+ private function _getCnonce()
+ {
+ // TODO: I reused the nonce function from the DigestMD5 class.
+ // I should probably make this a protected function in Common.
+ if (@file_exists('/dev/urandom') && $fd = @fopen('/dev/urandom', 'r')) {
+ return base64_encode(fread($fd, 32));
+
+ } elseif (@file_exists('/dev/random') && $fd = @fopen('/dev/random', 'r')) {
+ return base64_encode(fread($fd, 32));
+
+ } else {
+ $str = '';
+ for ($i=0; $i<32; $i++) {
+ $str .= chr(mt_rand(0, 255));
+ }
+
+ return base64_encode($str);
+ }
+ }
+
+}
+
+?>

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