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Diffstat (limited to 'program/lib/Auth/SASL/SCRAM.php')
| -rw-r--r-- | program/lib/Auth/SASL/SCRAM.php | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/program/lib/Auth/SASL/SCRAM.php b/program/lib/Auth/SASL/SCRAM.php new file mode 100644 index 000000000..cbca500e4 --- /dev/null +++ b/program/lib/Auth/SASL/SCRAM.php @@ -0,0 +1,306 @@ +<?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); + } + } + +} + +?> |