<?php
/**
 * xmlseclibs.php
 *
 * Copyright (c) 2007-2015, Robert Richards <rrichards@cdatazone.org>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   * 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.
 *
 *   * Neither the name of Robert Richards nor the names of his
 *     contributors may 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     Robert Richards <rrichards@cdatazone.org>
 * @copyright  2007-2015 Robert Richards <rrichards@cdatazone.org>
 * @license    http://www.opensource.org/licenses/bsd-license.php  BSD License
 * @version    2.0.0 modified
 */

class XMLSecurityKey {
    const TRIPLEDES_CBC = 'http://www.w3.org/2001/04/xmlenc#tripledes-cbc';
    const AES128_CBC = 'http://www.w3.org/2001/04/xmlenc#aes128-cbc';
    const AES192_CBC = 'http://www.w3.org/2001/04/xmlenc#aes192-cbc';
    const AES256_CBC = 'http://www.w3.org/2001/04/xmlenc#aes256-cbc';
    const RSA_1_5 = 'http://www.w3.org/2001/04/xmlenc#rsa-1_5';
    const RSA_OAEP_MGF1P = 'http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p';
    const DSA_SHA1 = 'http://www.w3.org/2000/09/xmldsig#dsa-sha1';
    const RSA_SHA1 = 'http://www.w3.org/2000/09/xmldsig#rsa-sha1';
    const RSA_SHA256 = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256';
    const RSA_SHA384 = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha384';
    const RSA_SHA512 = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha512';
    const HMAC_SHA1 = 'http://www.w3.org/2000/09/xmldsig#hmac-sha1';

    private $cryptParams = array();
    public $type = 0;
    public $key = null;
    public $passphrase = "";
    public $iv = null;
    public $name = null;
    public $keyChain = null;
    public $isEncrypted = false;
    public $encryptedCtx = null;
    public $guid = null;

    /**
     * This variable contains the certificate as a string if this key represents an X509-certificate.
     * If this key doesn't represent a certificate, this will be null.
     */
    private $x509Certificate = null;

    /* This variable contains the certificate thunbprint if we have loaded an X509-certificate. */
    private $X509Thumbprint = null;

    public function __construct($type, $params=null) {
        switch ($type) {
            case (XMLSecurityKey::TRIPLEDES_CBC):
                $this->cryptParams['library'] = 'mcrypt';
                $this->cryptParams['cipher'] = MCRYPT_TRIPLEDES;
                $this->cryptParams['mode'] = MCRYPT_MODE_CBC;
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmlenc#tripledes-cbc';
                $this->cryptParams['keysize'] = 24;
                break;
            case (XMLSecurityKey::AES128_CBC):
                $this->cryptParams['library'] = 'mcrypt';
                $this->cryptParams['cipher'] = MCRYPT_RIJNDAEL_128;
                $this->cryptParams['mode'] = MCRYPT_MODE_CBC;
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmlenc#aes128-cbc';
                $this->cryptParams['keysize'] = 16;
                break;
            case (XMLSecurityKey::AES192_CBC):
                $this->cryptParams['library'] = 'mcrypt';
                $this->cryptParams['cipher'] = MCRYPT_RIJNDAEL_128;
                $this->cryptParams['mode'] = MCRYPT_MODE_CBC;
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmlenc#aes192-cbc';
                $this->cryptParams['keysize'] = 24;
                break;
            case (XMLSecurityKey::AES256_CBC):
                $this->cryptParams['library'] = 'mcrypt';
                $this->cryptParams['cipher'] = MCRYPT_RIJNDAEL_128;
                $this->cryptParams['mode'] = MCRYPT_MODE_CBC;
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmlenc#aes256-cbc';
                $this->cryptParams['keysize'] = 32;
                break;
            case (XMLSecurityKey::RSA_1_5):
                $this->cryptParams['library'] = 'openssl';
                $this->cryptParams['padding'] = OPENSSL_PKCS1_PADDING;
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmlenc#rsa-1_5';
                if (is_array($params) && ! empty($params['type'])) {
                    if ($params['type'] == 'public' || $params['type'] == 'private') {
                        $this->cryptParams['type'] = $params['type'];
                        break;
                    }
                }
                throw new Exception('Certificate "type" (private/public) must be passed via parameters');
            case (XMLSecurityKey::RSA_OAEP_MGF1P):
                $this->cryptParams['library'] = 'openssl';
                $this->cryptParams['padding'] = OPENSSL_PKCS1_OAEP_PADDING;
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p';
                $this->cryptParams['hash'] = null;
                if (is_array($params) && ! empty($params['type'])) {
                    if ($params['type'] == 'public' || $params['type'] == 'private') {
                        $this->cryptParams['type'] = $params['type'];
                        break;
                    }
                }
                throw new Exception('Certificate "type" (private/public) must be passed via parameters');
            case (XMLSecurityKey::RSA_SHA1):
                $this->cryptParams['library'] = 'openssl';
                $this->cryptParams['method'] = 'http://www.w3.org/2000/09/xmldsig#rsa-sha1';
                $this->cryptParams['padding'] = OPENSSL_PKCS1_PADDING;
                if (is_array($params) && ! empty($params['type'])) {
                    if ($params['type'] == 'public' || $params['type'] == 'private') {
                        $this->cryptParams['type'] = $params['type'];
                        break;
                    }
                }
                throw new Exception('Certificate "type" (private/public) must be passed via parameters');
            case (XMLSecurityKey::RSA_SHA256):
                $this->cryptParams['library'] = 'openssl';
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256';
                $this->cryptParams['padding'] = OPENSSL_PKCS1_PADDING;
                $this->cryptParams['digest'] = 'SHA256';
                if (is_array($params) && ! empty($params['type'])) {
                    if ($params['type'] == 'public' || $params['type'] == 'private') {
                        $this->cryptParams['type'] = $params['type'];
                        break;
                    }
                }
                throw new Exception('Certificate "type" (private/public) must be passed via parameters');
            case (XMLSecurityKey::RSA_SHA384):
                $this->cryptParams['library'] = 'openssl';
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha384';
                $this->cryptParams['padding'] = OPENSSL_PKCS1_PADDING;
                $this->cryptParams['digest'] = 'SHA384';
                if (is_array($params) && ! empty($params['type'])) {
                    if ($params['type'] == 'public' || $params['type'] == 'private') {
                        $this->cryptParams['type'] = $params['type'];
                        break;
                    }
                }
                throw new Exception('Certificate "type" (private/public) must be passed via parameters');
            case (XMLSecurityKey::RSA_SHA512):
                $this->cryptParams['library'] = 'openssl';
                $this->cryptParams['method'] = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha512';
                $this->cryptParams['padding'] = OPENSSL_PKCS1_PADDING;
                $this->cryptParams['digest'] = 'SHA512';
                if (is_array($params) && ! empty($params['type'])) {
                    if ($params['type'] == 'public' || $params['type'] == 'private') {
                        $this->cryptParams['type'] = $params['type'];
                        break;
                    }
                }
                throw new Exception('Certificate "type" (private/public) must be passed via parameters');
            case (XMLSecurityKey::HMAC_SHA1):
                $this->cryptParams['library'] = $type;
                $this->cryptParams['method'] = 'http://www.w3.org/2000/09/xmldsig#hmac-sha1';
                break;
            default:
                throw new Exception('Invalid Key Type');
        }
        $this->type = $type;
    }

    /**
     * Retrieve the key size for the symmetric encryption algorithm..
     *
     * If the key size is unknown, or this isn't a symmetric encryption algorithm,
     * null is returned.
     *
     * @return int|null  The number of bytes in the key.
     */
    public function getSymmetricKeySize() {
        if (! isset($this->cryptParams['keysize'])) {
            return null;
        }
        return $this->cryptParams['keysize'];
    }
      
    public function generateSessionKey() {
        if (!isset($this->cryptParams['keysize'])) {
            throw new Exception('Unknown key size for type "' . $this->type . '".');
        }
        $keysize = $this->cryptParams['keysize'];
        
        if (function_exists('openssl_random_pseudo_bytes')) {
            /* We have PHP >= 5.3 - use openssl to generate session key. */
            $key = openssl_random_pseudo_bytes($keysize);
        } else {
            /* Generating random key using iv generation routines */
            $key = mcrypt_create_iv($keysize, MCRYPT_RAND);
        }
        
        if ($this->type === XMLSecurityKey::TRIPLEDES_CBC) {
            /* Make sure that the generated key has the proper parity bits set.
             * Mcrypt doesn't care about the parity bits, but others may care.
            */
            for ($i = 0; $i < strlen($key); $i++) {
                $byte = ord($key[$i]) & 0xfe;
                $parity = 1;
                for ($j = 1; $j < 8; $j++) {
                    $parity ^= ($byte >> $j) & 1;
                }
                $byte |= $parity;
                $key[$i] = chr($byte);
            }
        }
        
        $this->key = $key;
        return $key;
    }

    public static function getRawThumbprint($cert) {

        $arCert = explode("\n", $cert);
        $data = '';
        $inData = false;

        foreach ($arCert AS $curData) {
            if (! $inData) {
                if (strncmp($curData, '-----BEGIN CERTIFICATE', 22) == 0) {
                    $inData = true;
                }
            } else {
                if (strncmp($curData, '-----END CERTIFICATE', 20) == 0) {
                    break;
                }
                $data .= trim($curData);
            }
        }

        if (! empty($data)) {
            return strtolower(sha1(base64_decode($data)));
        }

        return null;
    }

    public function loadKey($key, $isFile=false, $isCert = false) {
        if ($isFile) {
            $this->key = file_get_contents($key);
        } else {
            $this->key = $key;
        }
        if ($isCert) {
            $this->key = openssl_x509_read($this->key);
            openssl_x509_export($this->key, $str_cert);
            $this->x509Certificate = $str_cert;
            $this->key = $str_cert;
        } else {
            $this->x509Certificate = null;
        }
        if ($this->cryptParams['library'] == 'openssl') {
            if ($this->cryptParams['type'] == 'public') {
                if ($isCert) {
                    /* Load the thumbprint if this is an X509 certificate. */
                    $this->X509Thumbprint = self::getRawThumbprint($this->key);
                }
                $this->key = openssl_get_publickey($this->key);
            } else {
                $this->key = openssl_get_privatekey($this->key, $this->passphrase);
            }
        } else if (isset($this->cryptParams['cipher']) && $this->cryptParams['cipher'] == MCRYPT_RIJNDAEL_128) {
            /* Check key length */
            switch ($this->type) {
                case (XMLSecurityKey::AES256_CBC):
                    if (strlen($this->key) < 25) {
                        throw new Exception('Key must contain at least 25 characters for this cipher');
                    }
                    break;
                case (XMLSecurityKey::AES192_CBC):
                    if (strlen($this->key) < 17) {
                        throw new Exception('Key must contain at least 17 characters for this cipher');
                    }
                    break;
            }
        }
    }

    private function encryptMcrypt($data) {
        $td = mcrypt_module_open($this->cryptParams['cipher'], '', $this->cryptParams['mode'], '');
        $this->iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
        mcrypt_generic_init($td, $this->key, $this->iv);
        if ($this->cryptParams['mode'] == MCRYPT_MODE_CBC) {
            $bs = mcrypt_enc_get_block_size($td);
            for ($datalen0=$datalen=strlen($data); (($datalen%$bs)!=($bs-1)); $datalen++)
                $data.=chr(mt_rand(1, 127));
            $data.=chr($datalen-$datalen0+1);
        }
        $encrypted_data = $this->iv.mcrypt_generic($td, $data);
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        return $encrypted_data;
    }

    private function decryptMcrypt($data) {
        $td = mcrypt_module_open($this->cryptParams['cipher'], '', $this->cryptParams['mode'], '');
        $iv_length = mcrypt_enc_get_iv_size($td);

        $this->iv = substr($data, 0, $iv_length);
        $data = substr($data, $iv_length);

        mcrypt_generic_init($td, $this->key, $this->iv);
        $decrypted_data = mdecrypt_generic($td, $data);
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        if ($this->cryptParams['mode'] == MCRYPT_MODE_CBC) {
            $dataLen = strlen($decrypted_data);
            $paddingLength = substr($decrypted_data, $dataLen - 1, 1);
            $decrypted_data = substr($decrypted_data, 0, $dataLen - ord($paddingLength));
        }
        return $decrypted_data;
    }

    private function encryptOpenSSL($data) {
        if ($this->cryptParams['type'] == 'public') {
            if (! openssl_public_encrypt($data, $encrypted_data, $this->key, $this->cryptParams['padding'])) {
                throw new Exception('Failure encrypting Data');
            }
        } else {
            if (! openssl_private_encrypt($data, $encrypted_data, $this->key, $this->cryptParams['padding'])) {
                throw new Exception('Failure encrypting Data');
            }
        }
        return $encrypted_data;
    }

    private function decryptOpenSSL($data) {
        if ($this->cryptParams['type'] == 'public') {
            if (! openssl_public_decrypt($data, $decrypted, $this->key, $this->cryptParams['padding'])) {
                throw new Exception('Failure decrypting Data');
            }
        } else {
            if (! openssl_private_decrypt($data, $decrypted, $this->key, $this->cryptParams['padding'])) {
                throw new Exception('Failure decrypting Data');
            }
        }
        return $decrypted;
    }

    private function signOpenSSL($data) {
        $algo = OPENSSL_ALGO_SHA1;
        if (! empty($this->cryptParams['digest'])) {
            $algo = $this->cryptParams['digest'];
        }
        if (! openssl_sign ($data, $signature, $this->key, $algo)) {
            throw new Exception('Failure Signing Data: ' . openssl_error_string() . ' - ' . $algo);
        }
        return $signature;
    }

    private function verifyOpenSSL($data, $signature) {
        $algo = OPENSSL_ALGO_SHA1;
        if (! empty($this->cryptParams['digest'])) {
            $algo = $this->cryptParams['digest'];
        }
        return openssl_verify ($data, $signature, $this->key, $algo);
    }

    public function encryptData($data) {
        switch ($this->cryptParams['library']) {
            case 'mcrypt':
                return $this->encryptMcrypt($data);
            case 'openssl':
                return $this->encryptOpenSSL($data);
        }
    }

    public function decryptData($data) {
        switch ($this->cryptParams['library']) {
            case 'mcrypt':
                return $this->decryptMcrypt($data);
            case 'openssl':
                return $this->decryptOpenSSL($data);
        }
    }

    public function signData($data) {
        switch ($this->cryptParams['library']) {
            case 'openssl':
                return $this->signOpenSSL($data);
            case (XMLSecurityKey::HMAC_SHA1):
                return hash_hmac("sha1", $data, $this->key, true);
        }
    }

    public function verifySignature($data, $signature) {
        switch ($this->cryptParams['library']) {
            case 'openssl':
                return $this->verifyOpenSSL($data, $signature);
            case (XMLSecurityKey::HMAC_SHA1):
                $expectedSignature = hash_hmac("sha1", $data, $this->key, true);
                return strcmp($signature, $expectedSignature) == 0;
        }
    }

    public function getAlgorithm() {
        return $this->cryptParams['method'];
    }

    static function makeAsnSegment($type, $string) {
        switch ($type){
            case 0x02:
                if (ord($string) > 0x7f)
                    $string = chr(0).$string;
                break;
            case 0x03:
                $string = chr(0).$string;
                break;
        }

        $length = strlen($string);

        if ($length < 128){
           $output = sprintf("%c%c%s", $type, $length, $string);
        } else if ($length < 0x0100){
           $output = sprintf("%c%c%c%s", $type, 0x81, $length, $string);
        } else if ($length < 0x010000) {
           $output = sprintf("%c%c%c%c%s", $type, 0x82, $length/0x0100, $length%0x0100, $string);
        } else {
            $output = null;
        }
        return($output);
    }

    /* Modulus and Exponent must already be base64 decoded */
    static function convertRSA($modulus, $exponent) {
        /* make an ASN publicKeyInfo */
        $exponentEncoding = XMLSecurityKey::makeAsnSegment(0x02, $exponent);
        $modulusEncoding = XMLSecurityKey::makeAsnSegment(0x02, $modulus);
        $sequenceEncoding = XMLSecurityKey:: makeAsnSegment(0x30, $modulusEncoding.$exponentEncoding);
        $bitstringEncoding = XMLSecurityKey::makeAsnSegment(0x03, $sequenceEncoding);
        $rsaAlgorithmIdentifier = pack("H*", "300D06092A864886F70D0101010500");
        $publicKeyInfo = XMLSecurityKey::makeAsnSegment (0x30, $rsaAlgorithmIdentifier.$bitstringEncoding);

        /* encode the publicKeyInfo in base64 and add PEM brackets */
        $publicKeyInfoBase64 = base64_encode($publicKeyInfo);
        $encoding = "-----BEGIN PUBLIC KEY-----\n";
        $offset = 0;
        while ($segment=substr($publicKeyInfoBase64, $offset, 64)){
           $encoding = $encoding.$segment."\n";
           $offset += 64;
        }
        return $encoding."-----END PUBLIC KEY-----\n";
    }

    public function serializeKey($parent) {

    }
    


    /**
     * Retrieve the X509 certificate this key represents.
     *
     * Will return the X509 certificate in PEM-format if this key represents
     * an X509 certificate.
     *
     * @return  The X509 certificate or null if this key doesn't represent an X509-certificate.
     */
    public function getX509Certificate() {
        return $this->x509Certificate;
    }

    /* Get the thumbprint of this X509 certificate.
     *
     * Returns:
     *  The thumbprint as a lowercase 40-character hexadecimal number, or null
     *  if this isn't a X509 certificate.
     */
    public function getX509Thumbprint() {
        return $this->X509Thumbprint;
    }


    /**
     * Create key from an EncryptedKey-element.
     *
     * @param DOMElement $element  The EncryptedKey-element.
     * @return XMLSecurityKey  The new key.
     */
    public static function fromEncryptedKeyElement(DOMElement $element) {

        $objenc = new XMLSecEnc();
        $objenc->setNode($element);
        if (! $objKey = $objenc->locateKey()) {
            throw new Exception("Unable to locate algorithm for this Encrypted Key");
        }
        $objKey->isEncrypted = true;
        $objKey->encryptedCtx = $objenc;
        XMLSecEnc::staticLocateKeyInfo($objKey, $element);
        return $objKey;
    }

}


class XMLSecurityDSig {
    const XMLDSIGNS = 'http://www.w3.org/2000/09/xmldsig#';
    const SHA1 = 'http://www.w3.org/2000/09/xmldsig#sha1';
    const SHA256 = 'http://www.w3.org/2001/04/xmlenc#sha256';
    const SHA384 = 'http://www.w3.org/2001/04/xmldsig-more#sha384';
    const SHA512 = 'http://www.w3.org/2001/04/xmlenc#sha512';
    const RIPEMD160 = 'http://www.w3.org/2001/04/xmlenc#ripemd160';

    const C14N = 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315';
    const C14N_COMMENTS = 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments';
    const EXC_C14N = 'http://www.w3.org/2001/10/xml-exc-c14n#';
    const EXC_C14N_COMMENTS = 'http://www.w3.org/2001/10/xml-exc-c14n#WithComments';

    const template = '<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
  <ds:SignedInfo>
    <ds:SignatureMethod />
  </ds:SignedInfo>
</ds:Signature>';

    public $sigNode = null;
    public $idKeys = array();
    public $idNS = array();
    private $signedInfo = null;
    private $xPathCtx = null;
    private $canonicalMethod = null;
    private $prefix = 'ds';
    private $searchpfx = 'secdsig';

    /* This variable contains an associative array of validated nodes. */
    private $validatedNodes = null;

    public function __construct() {
        $sigdoc = new DOMDocument();
        $sigdoc->loadXML(XMLSecurityDSig::template);
        $this->sigNode = $sigdoc->documentElement;
    }

    private function resetXPathObj() {
        $this->xPathCtx = null;
    }
    
    private function getXPathObj() {
        if (empty($this->xPathCtx) && ! empty($this->sigNode)) {
            $xpath = new DOMXPath($this->sigNode->ownerDocument);
            $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
            $this->xPathCtx = $xpath;
        }
        return $this->xPathCtx;
    }

    static function generateGUID($prefix='pfx') {
        $uuid = md5(uniqid(mt_rand(), true));
        $guid =  $prefix.substr($uuid,0,8)."-".
                substr($uuid,8,4)."-".
                substr($uuid,12,4)."-".
                substr($uuid,16,4)."-".
                substr($uuid,20,12);
        return $guid;
    }

    public function locateSignature($objDoc, $pos=0) {
        if ($objDoc instanceof DOMDocument) {
            $doc = $objDoc;
        } else {
            $doc = $objDoc->ownerDocument;
        }
        if ($doc) {
            $xpath = new DOMXPath($doc);
            $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
            $query = ".//secdsig:Signature";
            $nodeset = $xpath->query($query, $objDoc);
            $this->sigNode = $nodeset->item($pos);
            return $this->sigNode;
        }
        return null;
    }

    public function createNewSignNode($name, $value=null) {
        $doc = $this->sigNode->ownerDocument;
        if (! is_null($value)) {
            $node = $doc->createElementNS(XMLSecurityDSig::XMLDSIGNS, $this->prefix.':'.$name, $value);
        } else {
            $node = $doc->createElementNS(XMLSecurityDSig::XMLDSIGNS, $this->prefix.':'.$name);
        }
        return $node;
    }

    public function setCanonicalMethod($method) {
        switch ($method) {
            case 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315':
            case 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments':
            case 'http://www.w3.org/2001/10/xml-exc-c14n#':
            case 'http://www.w3.org/2001/10/xml-exc-c14n#WithComments':
                $this->canonicalMethod = $method;
                break;
            default:
                throw new Exception('Invalid Canonical Method');
        }
        if ($xpath = $this->getXPathObj()) {
            $query = './'.$this->searchpfx.':SignedInfo';
            $nodeset = $xpath->query($query, $this->sigNode);
            if ($sinfo = $nodeset->item(0)) {
                $query = './'.$this->searchpfx.'CanonicalizationMethod';
                $nodeset = $xpath->query($query, $sinfo);
                if (! ($canonNode = $nodeset->item(0))) {
                    $canonNode = $this->createNewSignNode('CanonicalizationMethod');
                    $sinfo->insertBefore($canonNode, $sinfo->firstChild);
                }
                $canonNode->setAttribute('Algorithm', $this->canonicalMethod);
            }
        }
    }

    private function canonicalizeData($node, $canonicalmethod, $arXPath=null, $prefixList=null) {
        $exclusive = false;
        $withComments = false;
        switch ($canonicalmethod) {
            case 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315':
                $exclusive = false;
                $withComments = false;
                break;
            case 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments':
                $withComments = true;
                break;
            case 'http://www.w3.org/2001/10/xml-exc-c14n#':
                $exclusive = true;
                break;
            case 'http://www.w3.org/2001/10/xml-exc-c14n#WithComments':
                $exclusive = true;
                $withComments = true;
                break;
        }
        
        if (is_null($arXPath) && ($node instanceof DOMNode) && ($node->ownerDocument !== null) && $node->isSameNode($node->ownerDocument->documentElement)) {
            /* Check for any PI or comments as they would have been excluded */
            $element = $node;
            while ($refnode = $element->previousSibling) {
                if ($refnode->nodeType == XML_PI_NODE || (($refnode->nodeType == XML_COMMENT_NODE) && $withComments)) {
                    break;
                }
                $element = $refnode;
            }
            if ($refnode == null) {
                $node = $node->ownerDocument;
            }
        }
        
        return $node->C14N($exclusive, $withComments, $arXPath, $prefixList);
    }

    public function canonicalizeSignedInfo() {

        $doc = $this->sigNode->ownerDocument;
        $canonicalmethod = null;
        if ($doc) {
            $xpath = $this->getXPathObj();
            $query = "./secdsig:SignedInfo";
            $nodeset = $xpath->query($query, $this->sigNode);
            if ($signInfoNode = $nodeset->item(0)) {
                $query = "./secdsig:CanonicalizationMethod";
                $nodeset = $xpath->query($query, $signInfoNode);
                if ($canonNode = $nodeset->item(0)) {
                    $canonicalmethod = $canonNode->getAttribute('Algorithm');
                }
                $this->signedInfo = $this->canonicalizeData($signInfoNode, $canonicalmethod);
                return $this->signedInfo;
            }
        }
        return null;
    }

    public function calculateDigest ($digestAlgorithm, $data, $encode = true) {
        switch ($digestAlgorithm) {
            case XMLSecurityDSig::SHA1:
                $alg = 'sha1';
                break;
            case XMLSecurityDSig::SHA256:
                $alg = 'sha256';
                break;
            case XMLSecurityDSig::SHA384:
                $alg = 'sha384';
                break;
            case XMLSecurityDSig::SHA512:
                $alg = 'sha512';
                break;
            case XMLSecurityDSig::RIPEMD160:
                $alg = 'ripemd160';
                break;
            default:
                throw new Exception("Cannot validate digest: Unsupported Algorithm <$digestAlgorithm>");
        }

        $digest = hash($alg, $data, true);
        if ($encode) {
            $digest = base64_encode($digest);
        }
        return $digest;
    }

    public function validateDigest($refNode, $data) {
        $xpath = new DOMXPath($refNode->ownerDocument);
        $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
        $query = 'string(./secdsig:DigestMethod/@Algorithm)';
        $digestAlgorithm = $xpath->evaluate($query, $refNode);
        $digValue = $this->calculateDigest($digestAlgorithm, $data, false);
        $query = 'string(./secdsig:DigestValue)';
        $digestValue = $xpath->evaluate($query, $refNode);
        return ($digValue === base64_decode($digestValue));
    }

    public function processTransforms($refNode, $objData, $includeCommentNodes = true) {
        $data = $objData;
        $xpath = new DOMXPath($refNode->ownerDocument);
        $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
        $query = './secdsig:Transforms/secdsig:Transform';
        $nodelist = $xpath->query($query, $refNode);
        $canonicalMethod = 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315';
        $arXPath = null;
        $prefixList = null;
        foreach ($nodelist AS $transform) {
            $algorithm = $transform->getAttribute("Algorithm");
            switch ($algorithm) {
                case 'http://www.w3.org/2001/10/xml-exc-c14n#':
                case 'http://www.w3.org/2001/10/xml-exc-c14n#WithComments':

                    if(!$includeCommentNodes) {
                        /* We remove comment nodes by forcing it to use a canonicalization
                         * without comments.
                         */
                        $canonicalMethod = 'http://www.w3.org/2001/10/xml-exc-c14n#';
                    } else {
                        $canonicalMethod = $algorithm;
                    }

                    $node = $transform->firstChild;
                    while ($node) {
                        if ($node->localName == 'InclusiveNamespaces') {
                            if ($pfx = $node->getAttribute('PrefixList')) {
                                $arpfx = array();
                                $pfxlist = explode(" ", $pfx);
                                foreach ($pfxlist AS $pfx) {
                                    $val = trim($pfx);
                                    if (! empty($val)) {
                                        $arpfx[] = $val;
                                    }
                                }
                                if (count($arpfx) > 0) {
                                    $prefixList = $arpfx;
                                }
                            }
                            break;
                        }
                        $node = $node->nextSibling;
                    }
            break;
                case 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315':
                case 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments':
                    if(!$includeCommentNodes) {
                        /* We remove comment nodes by forcing it to use a canonicalization
                         * without comments.
                         */
                        $canonicalMethod = 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315';
                    } else {
                        $canonicalMethod = $algorithm;
                    }

                    break;
                case 'http://www.w3.org/TR/1999/REC-xpath-19991116':
                    $node = $transform->firstChild;
                    while ($node) {
                        if ($node->localName == 'XPath') {
                            $arXPath = array();
                            $arXPath['query'] = '(.//. | .//@* | .//namespace::*)['.$node->nodeValue.']';
                            $arXpath['namespaces'] = array();
                            $nslist = $xpath->query('./namespace::*', $node);
                            foreach ($nslist AS $nsnode) {
                                if ($nsnode->localName != "xml") {
                                    $arXPath['namespaces'][$nsnode->localName] = $nsnode->nodeValue;
                                }
                            }
                            break;
                        }
                        $node = $node->nextSibling;
                    }
                    break;
            }
        }
        if ($data instanceof DOMNode) {
            $data = $this->canonicalizeData($objData, $canonicalMethod, $arXPath, $prefixList);
        }
        return $data;
    }

    public function processRefNode($refNode) {
        $dataObject = null;

        /*
         * Depending on the URI, we may not want to include comments in the result
         * See: http://www.w3.org/TR/xmldsig-core/#sec-ReferenceProcessingModel
         */
        $includeCommentNodes = true;

        if ($uri = $refNode->getAttribute("URI")) {
            $arUrl = parse_url($uri);
            if (empty($arUrl['path'])) {
                if ($identifier = $arUrl['fragment']) {

                    /* This reference identifies a node with the given id by using
                     * a URI on the form "#identifier". This should not include comments.
                     */
                    $includeCommentNodes = false;

                    $xPath = new DOMXPath($refNode->ownerDocument);
                    if ($this->idNS && is_array($this->idNS)) {
                        foreach ($this->idNS AS $nspf=>$ns) {
                            $xPath->registerNamespace($nspf, $ns);
                        }
                    }
                    $iDlist = '@Id="'.$identifier.'"';
                    if (is_array($this->idKeys)) {
                        foreach ($this->idKeys AS $idKey) {
                            $iDlist .= " or @$idKey='$identifier'";
                        }
                    }
                    $query = '//*['.$iDlist.']';
                    $dataObject = $xPath->query($query)->item(0);
                } else {
                    $dataObject = $refNode->ownerDocument;
                }
            }
        } else {
            /* This reference identifies the root node with an empty URI. This should
             * not include comments.
             */
            $includeCommentNodes = false;

            $dataObject = $refNode->ownerDocument;
        }
        $data = $this->processTransforms($refNode, $dataObject, $includeCommentNodes);
        if (!$this->validateDigest($refNode, $data)) {
            return false;
        }

        if ($dataObject instanceof DOMNode) {
            /* Add this node to the list of validated nodes. */
            if(! empty($identifier)) {
                $this->validatedNodes[$identifier] = $dataObject;
            } else {
                $this->validatedNodes[] = $dataObject;
            }
        }

        return true;
    }

    public function getRefNodeID($refNode) {
        if ($uri = $refNode->getAttribute("URI")) {
            $arUrl = parse_url($uri);
            if (empty($arUrl['path'])) {
                if ($identifier = $arUrl['fragment']) {
                    return $identifier;
                }
            }
        }
        return null;
    }

    public function getRefIDs() {
        $refids = array();

        $xpath = $this->getXPathObj();
        $query = "./secdsig:SignedInfo/secdsig:Reference";
        $nodeset = $xpath->query($query, $this->sigNode);
        if ($nodeset->length == 0) {
            throw new Exception("Reference nodes not found");
        }
        foreach ($nodeset AS $refNode) {
            $refids[] = $this->getRefNodeID($refNode);
        }
        return $refids;
    }

    public function validateReference() {
        $docElem = $this->sigNode->ownerDocument->documentElement;
        if (! $docElem->isSameNode($this->sigNode)) {
            $this->sigNode->parentNode->removeChild($this->sigNode);
        }
        $xpath = $this->getXPathObj();
        $query = "./secdsig:SignedInfo/secdsig:Reference";
        $nodeset = $xpath->query($query, $this->sigNode);
        if ($nodeset->length == 0) {
            throw new Exception("Reference nodes not found");
        }
        
        /* Initialize/reset the list of validated nodes. */
        $this->validatedNodes = array();
        
        foreach ($nodeset AS $refNode) {
            if (! $this->processRefNode($refNode)) {
                /* Clear the list of validated nodes. */
                $this->validatedNodes = null;
                throw new Exception("Reference validation failed");
            }
        }
        return true;
    }

    private function addRefInternal($sinfoNode, $node, $algorithm, $arTransforms=null, $options=null) {
        $prefix = null;
        $prefix_ns = null;
        $id_name = 'Id';
        $overwrite_id  = true;
        $force_uri = false;

        if (is_array($options)) {
            $prefix = empty($options['prefix'])?null:$options['prefix'];
            $prefix_ns = empty($options['prefix_ns'])?null:$options['prefix_ns'];
            $id_name = empty($options['id_name'])?'Id':$options['id_name'];
            $overwrite_id = !isset($options['overwrite'])?true:(bool)$options['overwrite'];
            $force_uri = !isset($options['force_uri'])?false:(bool)$options['force_uri'];
        }

        $attname = $id_name;
        if (! empty($prefix)) {
            $attname = $prefix.':'.$attname;
        }

        $refNode = $this->createNewSignNode('Reference');
        $sinfoNode->appendChild($refNode);

        if (! $node instanceof DOMDocument) {
            $uri = null;
            if (! $overwrite_id) {
                $uri = $prefix_ns ? $node->getAttributeNS($prefix_ns, $id_name) : $node->getAttribute($id_name);
            }
            if (empty($uri)) {
                $uri = XMLSecurityDSig::generateGUID();
                $node->setAttributeNS($prefix_ns, $attname, $uri);
            }
            $refNode->setAttribute("URI", '#'.$uri);
        } elseif ($force_uri) {
            $refNode->setAttribute("URI", '');
        }

        $transNodes = $this->createNewSignNode('Transforms');
        $refNode->appendChild($transNodes);

        if (is_array($arTransforms)) {
            foreach ($arTransforms AS $transform) {
                $transNode = $this->createNewSignNode('Transform');
                $transNodes->appendChild($transNode);
                if (is_array($transform) && 
                    (! empty($transform['http://www.w3.org/TR/1999/REC-xpath-19991116'])) && 
                    (! empty($transform['http://www.w3.org/TR/1999/REC-xpath-19991116']['query']))) {
                    $transNode->setAttribute('Algorithm', 'http://www.w3.org/TR/1999/REC-xpath-19991116');
                    $XPathNode = $this->createNewSignNode('XPath', $transform['http://www.w3.org/TR/1999/REC-xpath-19991116']['query']);
                    $transNode->appendChild($XPathNode);
                    if (! empty($transform['http://www.w3.org/TR/1999/REC-xpath-19991116']['namespaces'])) {
                        foreach ($transform['http://www.w3.org/TR/1999/REC-xpath-19991116']['namespaces'] AS $prefix => $namespace) {
                            $XPathNode->setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:$prefix", $namespace);
                        }
                    }
                } else {
                    $transNode->setAttribute('Algorithm', $transform);
                }
            }
        } elseif (! empty($this->canonicalMethod)) {
            $transNode = $this->createNewSignNode('Transform');
            $transNodes->appendChild($transNode);
            $transNode->setAttribute('Algorithm', $this->canonicalMethod);
        }

        $canonicalData = $this->processTransforms($refNode, $node);
        $digValue = $this->calculateDigest($algorithm, $canonicalData);

        $digestMethod = $this->createNewSignNode('DigestMethod');
        $refNode->appendChild($digestMethod);
        $digestMethod->setAttribute('Algorithm', $algorithm);

        $digestValue = $this->createNewSignNode('DigestValue', $digValue);
        $refNode->appendChild($digestValue);
    }

    public function addReference($node, $algorithm, $arTransforms=null, $options=null) {
        if ($xpath = $this->getXPathObj()) {
            $query = "./secdsig:SignedInfo";
            $nodeset = $xpath->query($query, $this->sigNode);
            if ($sInfo = $nodeset->item(0)) {
                $this->addRefInternal($sInfo, $node, $algorithm, $arTransforms, $options);
            }
        }
    }

    public function addReferenceList($arNodes, $algorithm, $arTransforms=null, $options=null) {
        if ($xpath = $this->getXPathObj()) {
            $query = "./secdsig:SignedInfo";
            $nodeset = $xpath->query($query, $this->sigNode);
            if ($sInfo = $nodeset->item(0)) {
                foreach ($arNodes AS $node) {
                    $this->addRefInternal($sInfo, $node, $algorithm, $arTransforms, $options);
                }
            }
        }
    }

   public function addObject($data, $mimetype=null, $encoding=null) {
      $objNode = $this->createNewSignNode('Object');
      $this->sigNode->appendChild($objNode);
      if (! empty($mimetype)) {
         $objNode->setAttribute('MimeType', $mimetype);
      }
      if (! empty($encoding)) {
         $objNode->setAttribute('Encoding', $encoding);
      }

      if ($data instanceof DOMElement) {
         $newData = $this->sigNode->ownerDocument->importNode($data, true);
      } else {
         $newData = $this->sigNode->ownerDocument->createTextNode($data);
      }
      $objNode->appendChild($newData);

      return $objNode;
   }

    public function locateKey($node=null) {
        if (empty($node)) {
            $node = $this->sigNode;
        }
        if (! $node instanceof DOMNode) {
            return null;
        }
        if ($doc = $node->ownerDocument) {
            $xpath = new DOMXPath($doc);
            $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
            $query = "string(./secdsig:SignedInfo/secdsig:SignatureMethod/@Algorithm)";
            $algorithm = $xpath->evaluate($query, $node);
            if ($algorithm) {
                try {
                    $objKey = new XMLSecurityKey($algorithm, array('type'=>'public'));
                } catch (Exception $e) {
                    return null;
                }
                return $objKey;
            }
        }
        return null;
    }

    public function verify($objKey) {
        $doc = $this->sigNode->ownerDocument;
        $xpath = new DOMXPath($doc);
        $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
        $query = "string(./secdsig:SignatureValue)";
        $sigValue = $xpath->evaluate($query, $this->sigNode);
        if (empty($sigValue)) {
            throw new Exception("Unable to locate SignatureValue");
        }
        return $objKey->verifySignature($this->signedInfo, base64_decode($sigValue));
    }

    public function signData($objKey, $data) {
        return $objKey->signData($data);
    }

    public function sign($objKey, $appendToNode = null) {
        // If we have a parent node append it now so C14N properly works
        if ($appendToNode != null) {
            $this->resetXPathObj();
            $this->appendSignature($appendToNode);
            $this->sigNode = $appendToNode->lastChild;
        }
        if ($xpath = $this->getXPathObj()) {
            $query = "./secdsig:SignedInfo";
            $nodeset = $xpath->query($query, $this->sigNode);
            if ($sInfo = $nodeset->item(0)) {
                $query = "./secdsig:SignatureMethod";
                $nodeset = $xpath->query($query, $sInfo);
                $sMethod = $nodeset->item(0);
                $sMethod->setAttribute('Algorithm', $objKey->type);
                $data = $this->canonicalizeData($sInfo, $this->canonicalMethod);
                $sigValue = base64_encode($this->signData($objKey, $data));
                $sigValueNode = $this->createNewSignNode('SignatureValue', $sigValue);
                if ($infoSibling = $sInfo->nextSibling) {
                    $infoSibling->parentNode->insertBefore($sigValueNode, $infoSibling);
                } else {
                    $this->sigNode->appendChild($sigValueNode);
                }
            }
        }
    }

    public function appendCert() {

    }

    public function appendKey($objKey, $parent=null) {
        $objKey->serializeKey($parent);
    }


    /**
     * This function inserts the signature element.
     *
     * The signature element will be appended to the element, unless $beforeNode is specified. If $beforeNode
     * is specified, the signature element will be inserted as the last element before $beforeNode.
     *
     * @param $node  The node the signature element should be inserted into.
     * @param $beforeNode  The node the signature element should be located before.
     * 
     * @return DOMNode The signature element node
     */
    public function insertSignature($node, $beforeNode = null) {

        $document = $node->ownerDocument;
        $signatureElement = $document->importNode($this->sigNode, true);

        if($beforeNode == null) {
            return $node->insertBefore($signatureElement);
        } else {
            return $node->insertBefore($signatureElement, $beforeNode);
        }
    }

    public function appendSignature($parentNode, $insertBefore = false) {
        $beforeNode = $insertBefore ? $parentNode->firstChild : null;
        return $this->insertSignature($parentNode, $beforeNode);
    }

    static function get509XCert($cert, $isPEMFormat=true) {
        $certs = XMLSecurityDSig::staticGet509XCerts($cert, $isPEMFormat);
        if (! empty($certs)) {
            return $certs[0];
        }
        return '';
    }

    static function staticGet509XCerts($certs, $isPEMFormat=true) {
        if ($isPEMFormat) {
            $data = '';
            $certlist = array();
            $arCert = explode("\n", $certs);
            $inData = false;
            foreach ($arCert AS $curData) {
                if (! $inData) {
                    if (strncmp($curData, '-----BEGIN CERTIFICATE', 22) == 0) {
                        $inData = true;
                    }
                } else {
                    if (strncmp($curData, '-----END CERTIFICATE', 20) == 0) {
                        $inData = false;
                        $certlist[] = $data;
                        $data = '';
                        continue;
                    }
                    $data .= trim($curData);
                }
            }
            return $certlist;
        } else {
            return array($certs);
        }
    }

    static function staticAdd509Cert($parentRef, $cert, $isPEMFormat=true, $isURL=false, $xpath=null, $options=null) {
        if ($isURL) {
            $cert = file_get_contents($cert);
        }
        if (! $parentRef instanceof DOMElement) {
            throw new Exception('Invalid parent Node parameter');
        }
        
        list($parentRef, $keyInfo) = self::auxKeyInfo($parentRef, $xpath);
        
        // Add all certs if there are more than one
        $certs = XMLSecurityDSig::staticGet509XCerts($cert, $isPEMFormat);

        $baseDoc = $parentRef->ownerDocument;
        // Attach X509 data node
        $x509DataNode = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:X509Data');
        $keyInfo->appendChild($x509DataNode);

        $issuerSerial = false;
        $subjectName = false;
        if (is_array($options)) {
            if (! empty($options['issuerSerial'])) {
                $issuerSerial = true;
            }
            if (! empty($options['subjectName'])) {
                $subjectName = true;
            }
        }
        
        // Attach all certificate nodes and any additional data
        foreach ($certs as $X509Cert){
            if ($issuerSerial || $subjectName) {
                if ($certData = openssl_x509_parse("-----BEGIN CERTIFICATE-----\n".chunk_split($X509Cert, 64, "\n")."-----END CERTIFICATE-----\n")) {
                    if ($subjectName && ! empty($certData['subject'])) {
                        if (is_array($certData['subject'])) {
                            $parts = array();
                            foreach ($certData['subject'] AS $key => $value) {
                                if (is_array($value)) {
                                    foreach ($value as $valueElement) {
                                        array_unshift($parts, "$key=$valueElement");
                                    }
                                } else {
                                    array_unshift($parts, "$key=$value");
                                }
                            }
                            $subjectNameValue = implode(',', $parts);
                        } else {
                            $subjectNameValue = $certData['issuer'];
                        }
                        $x509SubjectNode = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:X509SubjectName', $subjectNameValue);
                        $x509DataNode->appendChild($x509SubjectNode);
                    }
                    if ($issuerSerial && ! empty($certData['issuer']) && ! empty($certData['serialNumber'])) {
                        if (is_array($certData['issuer'])) {
                            $parts = array();
                            foreach ($certData['issuer'] AS $key => $value) {
                                array_unshift($parts, "$key=$value");
                            }
                            $issuerName = implode(',', $parts);
                        } else {
                            $issuerName = $certData['issuer'];
                        }
                        
                        $x509IssuerNode = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:X509IssuerSerial');
                        $x509DataNode->appendChild($x509IssuerNode);
                        
                        $x509Node = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:X509IssuerName', $issuerName);
                        $x509IssuerNode->appendChild($x509Node);
                        $x509Node = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:X509SerialNumber', $certData['serialNumber']);
                        $x509IssuerNode->appendChild($x509Node);
                    }
                }
                
            }
            $x509CertNode = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:X509Certificate', $X509Cert);
            $x509DataNode->appendChild($x509CertNode);
        }
    }

    public function add509Cert($cert, $isPEMFormat=true, $isURL=false, $options=null) {
         if ($xpath = $this->getXPathObj()) {
            self::staticAdd509Cert($this->sigNode, $cert, $isPEMFormat, $isURL, $xpath, $options);
         }
    }
    
    /**
     * This function appends a node to the KeyInfo.
     *
     * The KeyInfo element will be created if one does not exist in the document.
     *
     * @param DOMNode $node The node to append to the KeyInfo.
     * 
     * @return DOMNode The KeyInfo element node
     */
    public function appendToKeyInfo($node) {
        $parentRef = $this->sigNode;

        $xpath = $this->getXPathObj();

        list($parentRef, $keyInfo) = self::auxKeyInfo($parentRef, $xpath);
                
        $keyInfo->appendChild($node);
        
        return $keyInfo;
    }
    
    static function auxKeyInfo($parentRef, $xpath=null)
    {
        $baseDoc = $parentRef->ownerDocument;
        if (empty($xpath)) {
            $xpath = new DOMXPath($parentRef->ownerDocument);
            $xpath->registerNamespace('secdsig', XMLSecurityDSig::XMLDSIGNS);
        }
        
        $query = "./secdsig:KeyInfo";
        $nodeset = $xpath->query($query, $parentRef);
        $keyInfo = $nodeset->item(0);
        if (! $keyInfo) {
            $inserted = false;
            $keyInfo = $baseDoc->createElementNS(XMLSecurityDSig::XMLDSIGNS, 'ds:KeyInfo');

            $query = "./secdsig:Object";
            $nodeset = $xpath->query($query, $parentRef);
            if ($sObject = $nodeset->item(0)) {
                $sObject->parentNode->insertBefore($keyInfo, $sObject);
                $inserted = true;
            }

            if (! $inserted) {
                $parentRef->appendChild($keyInfo);
            }
        }
        return array($parentRef, $keyInfo);
    }

    /* This function retrieves an associative array of the validated nodes.
     *
     * The array will contain the id of the referenced node as the key and the node itself
     * as the value.
     *
     * Returns:
     *  An associative array of validated nodes or null if no nodes have been validated.
     */
    public function getValidatedNodes() {
        return $this->validatedNodes;
    }
}


class XMLSecEnc {
    const template = "<xenc:EncryptedData xmlns:xenc='http://www.w3.org/2001/04/xmlenc#'>
   <xenc:CipherData>
      <xenc:CipherValue></xenc:CipherValue>
   </xenc:CipherData>
</xenc:EncryptedData>";

    const Element = 'http://www.w3.org/2001/04/xmlenc#Element';
    const Content = 'http://www.w3.org/2001/04/xmlenc#Content';
    const URI = 3;
    const XMLENCNS = 'http://www.w3.org/2001/04/xmlenc#';

    private $encdoc = null;
    private $rawNode = null;
    public $type = null;
    public $encKey = null;
    private $references = array();

    public function __construct() {
        $this->_resetTemplate();
    }

    private function _resetTemplate(){
        $this->encdoc = new DOMDocument();
        $this->encdoc->loadXML(XMLSecEnc::template);
    }

    public function addReference($name, $node, $type) {
        if (! $node instanceOf DOMNode) {
            throw new Exception('$node is not of type DOMNode');
        }
        $curencdoc = $this->encdoc;
        $this->_resetTemplate();
        $encdoc = $this->encdoc;
        $this->encdoc = $curencdoc;
        $refuri = XMLSecurityDSig::generateGUID();
        $element = $encdoc->documentElement;
        $element->setAttribute("Id", $refuri);
        $this->references[$name] = array("node" => $node, "type" => $type, "encnode" => $encdoc, "refuri" => $refuri);
    }

    public function setNode($node) {
        $this->rawNode = $node;
    }

    /**
     * Encrypt the selected node with the given key.
     *
     * @param XMLSecurityKey $objKey  The encryption key and algorithm.
     * @param bool $replace  Whether the encrypted node should be replaced in the original tree. Default is true.
     * @return DOMElement  The <xenc:EncryptedData>-element.
     */
    public function encryptNode($objKey, $replace=true) {
        $data = '';
        if (empty($this->rawNode)) {
            throw new Exception('Node to encrypt has not been set');
        }
        if (! $objKey instanceof XMLSecurityKey) {
            throw new Exception('Invalid Key');
        }
        $doc = $this->rawNode->ownerDocument;
        $xPath = new DOMXPath($this->encdoc);
        $objList = $xPath->query('/xenc:EncryptedData/xenc:CipherData/xenc:CipherValue');
        $cipherValue = $objList->item(0);
        if ($cipherValue == null) {
            throw new Exception('Error locating CipherValue element within template');
        }
        switch ($this->type) {
            case (XMLSecEnc::Element):
                $data = $doc->saveXML($this->rawNode);
                $this->encdoc->documentElement->setAttribute('Type', XMLSecEnc::Element);
                break;
            case (XMLSecEnc::Content):
                $children = $this->rawNode->childNodes;
                foreach ($children AS $child) {
                    $data .= $doc->saveXML($child);
                }
                $this->encdoc->documentElement->setAttribute('Type', XMLSecEnc::Content);
                break;
            default:
                throw new Exception('Type is currently not supported');
        }

        $encMethod = $this->encdoc->documentElement->appendChild($this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:EncryptionMethod'));
        $encMethod->setAttribute('Algorithm', $objKey->getAlgorithm());
        $cipherValue->parentNode->parentNode->insertBefore($encMethod, $cipherValue->parentNode->parentNode->firstChild);

        $strEncrypt = base64_encode($objKey->encryptData($data));
        $value = $this->encdoc->createTextNode($strEncrypt);
        $cipherValue->appendChild($value);

        if ($replace) {
            switch ($this->type) {
                case (XMLSecEnc::Element):
                    if ($this->rawNode->nodeType == XML_DOCUMENT_NODE) {
                        return $this->encdoc;
                    }
                    $importEnc = $this->rawNode->ownerDocument->importNode($this->encdoc->documentElement, true);
                    $this->rawNode->parentNode->replaceChild($importEnc, $this->rawNode);
                    return $importEnc;
                case (XMLSecEnc::Content):
                    $importEnc = $this->rawNode->ownerDocument->importNode($this->encdoc->documentElement, true);
                    while($this->rawNode->firstChild) {
                        $this->rawNode->removeChild($this->rawNode->firstChild);
                    }
                    $this->rawNode->appendChild($importEnc);
                    return $importEnc;
            }
        } else {
            return $this->encdoc->documentElement;
        }
    }

    public function encryptReferences($objKey) {
        $curRawNode = $this->rawNode;
        $curType = $this->type;
        foreach ($this->references AS $name=>$reference) {
            $this->encdoc = $reference["encnode"];
            $this->rawNode = $reference["node"];
            $this->type = $reference["type"];
            try {
                $encNode = $this->encryptNode($objKey);
                $this->references[$name]["encnode"] = $encNode;
            } catch (Exception $e) {
                $this->rawNode = $curRawNode;
                $this->type = $curType;
                throw $e;
            }
        }
        $this->rawNode = $curRawNode;
        $this->type = $curType;
    }

    /**
     * Retrieve the CipherValue text from this encrypted node.
     *
     * @return string|null  The Ciphervalue text, or null if no CipherValue is found.
     */
    public function getCipherValue() {
        if (empty($this->rawNode)) {
            throw new Exception('Node to decrypt has not been set');
        }

        $doc = $this->rawNode->ownerDocument;
        $xPath = new DOMXPath($doc);
        $xPath->registerNamespace('xmlencr', XMLSecEnc::XMLENCNS);
        /* Only handles embedded content right now and not a reference */
        $query = "./xmlencr:CipherData/xmlencr:CipherValue";
        $nodeset = $xPath->query($query, $this->rawNode);
        $node = $nodeset->item(0);

        if (!$node) {
                return null;
        }

        return base64_decode($node->nodeValue);
    }

    /**
     * Decrypt this encrypted node.
     *
     * The behaviour of this function depends on the value of $replace.
     * If $replace is false, we will return the decrypted data as a string.
     * If $replace is true, we will insert the decrypted element(s) into the
     * document, and return the decrypted element(s).
     *
     * @params XMLSecurityKey $objKey  The decryption key that should be used when decrypting the node.
     * @params boolean $replace  Whether we should replace the encrypted node in the XML document with the decrypted data. The default is true.
     * @return string|DOMElement  The decrypted data.
     */     
    public function decryptNode($objKey, $replace=true) {
        if (! $objKey instanceof XMLSecurityKey) {
            throw new Exception('Invalid Key');
        }

        $encryptedData = $this->getCipherValue();
        if ($encryptedData) {
            $decrypted = $objKey->decryptData($encryptedData);
            if ($replace) {
                switch ($this->type) {
                    case (XMLSecEnc::Element):
                        $newdoc = new DOMDocument();
                        $newdoc->loadXML($decrypted);
                        if ($this->rawNode->nodeType == XML_DOCUMENT_NODE) {
                            return $newdoc;
                        }
                        $importEnc = $this->rawNode->ownerDocument->importNode($newdoc->documentElement, true);
                        $this->rawNode->parentNode->replaceChild($importEnc, $this->rawNode);
                        return $importEnc;
                    case (XMLSecEnc::Content):
                        if ($this->rawNode->nodeType == XML_DOCUMENT_NODE) {
                            $doc = $this->rawNode;
                        } else {
                            $doc = $this->rawNode->ownerDocument;
                        }
                        $newFrag = $doc->createDocumentFragment();
                        $newFrag->appendXML($decrypted);
                        $parent = $this->rawNode->parentNode;
                        $parent->replaceChild($newFrag, $this->rawNode);
                        return $parent;
                    default:
                        return $decrypted;
                }
            } else {
                return $decrypted;
            }
        } else {
            throw new Exception("Cannot locate encrypted data");
        }
    }

    public function encryptKey($srcKey, $rawKey, $append=true) {
        if ((! $srcKey instanceof XMLSecurityKey) || (! $rawKey instanceof XMLSecurityKey)) {
            throw new Exception('Invalid Key');
        }
        $strEncKey = base64_encode($srcKey->encryptData($rawKey->key));
        $root = $this->encdoc->documentElement;
        $encKey = $this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:EncryptedKey');
        if ($append) {
            $keyInfo = $root->insertBefore($this->encdoc->createElementNS('http://www.w3.org/2000/09/xmldsig#', 'dsig:KeyInfo'), $root->firstChild);
            $keyInfo->appendChild($encKey);
        } else {
            $this->encKey = $encKey;
        }
        $encMethod = $encKey->appendChild($this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:EncryptionMethod'));
        $encMethod->setAttribute('Algorithm', $srcKey->getAlgorithm());
        if (! empty($srcKey->name)) {
            $keyInfo = $encKey->appendChild($this->encdoc->createElementNS('http://www.w3.org/2000/09/xmldsig#', 'dsig:KeyInfo'));
            $keyInfo->appendChild($this->encdoc->createElementNS('http://www.w3.org/2000/09/xmldsig#', 'dsig:KeyName', $srcKey->name));
        }
        $cipherData = $encKey->appendChild($this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:CipherData'));
        $cipherData->appendChild($this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:CipherValue', $strEncKey));
        if (is_array($this->references) && count($this->references) > 0) {
           $refList =  $encKey->appendChild($this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:ReferenceList'));
            foreach ($this->references AS $name=>$reference) {
                $refuri = $reference["refuri"];
                $dataRef = $refList->appendChild($this->encdoc->createElementNS(XMLSecEnc::XMLENCNS, 'xenc:DataReference'));
                $dataRef->setAttribute("URI", '#' . $refuri);
            }
        }
        return;
    }

    public function decryptKey($encKey) {
        if (! $encKey->isEncrypted) {
            throw new Exception("Key is not Encrypted");
        }
        if (empty($encKey->key)) {
            throw new Exception("Key is missing data to perform the decryption");
        }
        return $this->decryptNode($encKey, false);
    }

    public function locateEncryptedData($element) {
        if ($element instanceof DOMDocument) {
            $doc = $element;
        } else {
            $doc = $element->ownerDocument;
        }
        if ($doc) {
            $xpath = new DOMXPath($doc);
            $query = "//*[local-name()='EncryptedData' and namespace-uri()='".XMLSecEnc::XMLENCNS."']";
            $nodeset = $xpath->query($query);
            return $nodeset->item(0);
        }
        return null;
    }

    public function locateKey($node=null) {
        if (empty($node)) {
            $node = $this->rawNode;
        }
        if (! $node instanceof DOMNode) {
            return null;
        }
        if ($doc = $node->ownerDocument) {
            $xpath = new DOMXPath($doc);
            $xpath->registerNamespace('xmlsecenc', XMLSecEnc::XMLENCNS);
            $query = ".//xmlsecenc:EncryptionMethod";
            $nodeset = $xpath->query($query, $node);
            if ($encmeth = $nodeset->item(0)) {
                   $attrAlgorithm = $encmeth->getAttribute("Algorithm");
                try {
                    $objKey = new XMLSecurityKey($attrAlgorithm, array('type'=>'private'));
                } catch (Exception $e) {
                    return null;
                }
                return $objKey;
            }
        }
        return null;
    }

    static function staticLocateKeyInfo($objBaseKey=null, $node=null) {
        if (empty($node) || (! $node instanceof DOMNode)) {
            return null;
        }
        $doc = $node->ownerDocument;
        if (!$doc) {
            return null;
        }

        $xpath = new DOMXPath($doc);
        $xpath->registerNamespace('xmlsecenc', XMLSecEnc::XMLENCNS);
        $xpath->registerNamespace('xmlsecdsig', XMLSecurityDSig::XMLDSIGNS);
        $query = "./xmlsecdsig:KeyInfo";
        $nodeset = $xpath->query($query, $node);
        $encmeth = $nodeset->item(0);
        if (!$encmeth) {
            /* No KeyInfo in EncryptedData / EncryptedKey. */
            return $objBaseKey;
        }

        foreach ($encmeth->childNodes AS $child) {
            switch ($child->localName) {
                case 'KeyName':
                    if (! empty($objBaseKey)) {
                        $objBaseKey->name = $child->nodeValue;
                    }
                    break;
                case 'KeyValue':
                    foreach ($child->childNodes AS $keyval) {
                        switch ($keyval->localName) {
                            case 'DSAKeyValue':
                                throw new Exception("DSAKeyValue currently not supported");
                            case 'RSAKeyValue':
                                $modulus = null;
                                $exponent = null;
                                if ($modulusNode = $keyval->getElementsByTagName('Modulus')->item(0)) {
                                    $modulus = base64_decode($modulusNode->nodeValue);
                                }
                                if ($exponentNode = $keyval->getElementsByTagName('Exponent')->item(0)) {
                                    $exponent = base64_decode($exponentNode->nodeValue);
                                }
                                if (empty($modulus) || empty($exponent)) {
                                    throw new Exception("Missing Modulus or Exponent");
                                }
                                $publicKey = XMLSecurityKey::convertRSA($modulus, $exponent);
                                $objBaseKey->loadKey($publicKey);
                                break;
                        }
                    }
                    break;
                case 'RetrievalMethod':
                    $type = $child->getAttribute('Type');
                    if ($type !== 'http://www.w3.org/2001/04/xmlenc#EncryptedKey') {
                        /* Unsupported key type. */
                        break;
                    }
                    $uri = $child->getAttribute('URI');
                    if ($uri[0] !== '#') {
                        /* URI not a reference - unsupported. */
                        break;
                    }
                    $id = substr($uri, 1);

                    $query = "//xmlsecenc:EncryptedKey[@Id='$id']";
                    $keyElement = $xpath->query($query)->item(0);
                    if (!$keyElement) {
                        throw new Exception("Unable to locate EncryptedKey with @Id='$id'.");
                    }

                    return XMLSecurityKey::fromEncryptedKeyElement($keyElement);
                case 'EncryptedKey':
                    return XMLSecurityKey::fromEncryptedKeyElement($child);
                case 'X509Data':
                    if ($x509certNodes = $child->getElementsByTagName('X509Certificate')) {
                        if ($x509certNodes->length > 0) {
                            $x509cert = $x509certNodes->item(0)->textContent;
                            $x509cert = str_replace(array("\r", "\n", " "), "", $x509cert);
                            $x509cert = "-----BEGIN CERTIFICATE-----\n".chunk_split($x509cert, 64, "\n")."-----END CERTIFICATE-----\n";
                            $objBaseKey->loadKey($x509cert, false, true);
                        }
                    }
                    break;
            }
        }
        return $objBaseKey;
    }

    public function locateKeyInfo($objBaseKey=null, $node=null) {
        if (empty($node)) {
            $node = $this->rawNode;
        }
        return XMLSecEnc::staticLocateKeyInfo($objBaseKey, $node);
    }
}
