diff --git a/phpseclib/File/X509.php b/phpseclib/File/X509.php
index 29a0f89f..de13301d 100644
--- a/phpseclib/File/X509.php
+++ b/phpseclib/File/X509.php
@@ -117,12 +117,20 @@ class File_X509 {
     var $dn = array('rdnSequence' => array());
 
     /**
-     * Public or private key
+     * Public key
      *
      * @var String
      * @access private
      */
-    var $key;
+    var $publicKey;
+
+    /**
+     * Private key
+     *
+     * @var String
+     * @access private
+     */
+    var $privateKey;
 
     /**
      * Object identifiers for X.509 certificates
@@ -149,6 +157,41 @@ class File_X509 {
      */
     var $currentCert;
 
+    /**
+     * The signature subject
+     *
+     * There's no guarantee File_X509 is going to reencode an X.509 cert in the same way it was originally
+     * encoded so we take save the portion of the original cert that the signature would have made for. 
+     *
+     * @var String
+     * @access private
+     */
+    var $signatureSubject;
+
+    /**
+     * Certificate Start Date
+     *
+     * @var String
+     * @access private
+     */
+    var $startDate;
+
+    /**
+     * Certificate End Date
+     *
+     * @var String
+     * @access private
+     */
+    var $endDate;
+
+    /**
+     * Serial Number
+     *
+     * @var String
+     * @access private
+     */
+    var $serialNumber;
+
     /**
      * Default Constructor.
      *
@@ -984,6 +1027,8 @@ class File_X509 {
             '0.9.2342.19200300.100.1.25' => 'id-domainComponent',
             '1.2.840.113549.1.9' => 'pkcs-9',
             '1.2.840.113549.1.9.1' => 'id-emailAddress',
+            '2.5.4.17' => 'id-at-postalCode',
+            '2.5.4.9' => 'id-at-streetAddress',
             '2.5.29' => 'id-ce',
             '2.5.29.35' => 'id-ce-authorityKeyIdentifier',
             '2.5.29.14' => 'id-ce-subjectKeyIdentifier',
@@ -1112,12 +1157,20 @@ class File_X509 {
     /**
      * Load X.509 certificate
      *
+     * Returns an associative array describing the X.509 cert or a false if the cert failed to load
+     *
      * @param String $cert
      * @access public
-     * @return Array
+     * @return Mixed
      */
     function loadX509($cert)
     {
+        if (is_array($cert) && isset($cert['tbsCertificate'])) {
+            $this->currentCert = $cert;
+            unset($this->signatureSubject);
+            return false;
+        }
+
         $asn1 = new File_ASN1();
 
         /*
@@ -1198,6 +1251,10 @@ class File_X509 {
      */
     function saveX509($cert)
     {
+        if (!is_array($cert) || !isset($cert['tbsCertificate'])) {
+            return false;
+        }
+
         switch ($cert['tbsCertificate']['subjectPublicKeyInfo']['algorithm']['algorithm']) {
             case 'rsaEncryption':
                 $cert['tbsCertificate']['subjectPublicKeyInfo']['subjectPublicKey'] = 
@@ -1389,8 +1446,8 @@ class File_X509 {
         }
 
         switch (true) {
-            case time() < @strtotime($this->currentCert['tbsCertificate']['notBefore']):
-            case time() > @strtotime($this->currentCert['tbsCertificate']['notAfter']):
+            case time() < @strtotime($this->currentCert['tbsCertificate']['validity']['notBefore']):
+            case time() > @strtotime($this->currentCert['tbsCertificate']['validity']['notAfter']):
                 return false;
         }
 
@@ -1409,7 +1466,7 @@ class File_X509 {
      */
     function validateSignature($options = 0)
     {
-        if (!is_array($this->currentCert)) {
+        if (!is_array($this->currentCert) || !isset($this->signatureSubject)) {
             return false;
         }
 
@@ -1552,7 +1609,7 @@ class File_X509 {
             case 'id-at-organizationname':
             case 'organizationname':
             case 'o':
-                $type = 'id-at-organizationname';
+                $type = 'id-at-organizationName';
                 break;
             case 'id-at-dnqualifier':
             case 'dnqualifier':
@@ -1585,6 +1642,14 @@ class File_X509 {
             case 'serialnumber':
                 $type = 'id-at-serialNumber';
                 break;
+            case 'id-at-postalcode':
+            case 'postalcode':
+                $type = 'id-at-postalCode';
+                break;
+            case 'id-at-streetaddress':
+            case 'streetaddress':
+                $type = 'id-at-streetAddress';
+                break;
             default:
                 return false;
         }
@@ -1608,8 +1673,13 @@ class File_X509 {
      */
     function setDN($dn)
     {
-        // handles stuff generated by openssl_x509_parse()
         if (is_array($dn)) {
+            if (isset($dn['rdnSequence'])) {
+                $this->dn = $dn;
+                return true;
+            }
+
+            // handles stuff generated by openssl_x509_parse()
             foreach ($dn as $type => $value) {
                 if (!$this->setDNProp($type, $value)) {
                     return false;
@@ -1619,9 +1689,9 @@ class File_X509 {
         }
 
         // handles everything else
-        $results = preg_split('#((?:^|, )(?:C=|O=|OU=|CN=))#', $dn, -1, PREG_SPLIT_DELIM_CAPTURE);
+        $results = preg_split('#((?:^|, |/)(?:C=|O=|OU=|CN=|L=|ST=|postalCode=|streetAddress=|emailAddress=|serialNumber=))#', $dn, -1, PREG_SPLIT_DELIM_CAPTURE);
         for ($i = 1; $i < count($results); $i+=2) {
-            $type = trim($results[$i], ', =');
+            $type = trim($results[$i], ', =/');
             $value = $results[$i + 1];
             if (!$this->setDNProp($type, $value)) {
                 return false;
@@ -1632,7 +1702,88 @@ class File_X509 {
     }
 
     /**
-     * Set public or private key
+     * Get the Distinguished Name for a certificates subject
+     *
+     * @param Boolean $string optional
+     * @access public
+     * @return Boolean
+     */
+    function getDN($string = false)
+    {
+        if (!$string) {
+            return $this->currentCert['tbsCertificate']['subject'];
+        }
+
+        $start = true;
+        foreach ($this->currentCert['tbsCertificate']['subject']['rdnSequence'] as $field) {
+            $type = $field[0]['type'];
+            $value = $field[0]['value'];
+
+            $delim = ', ';
+            switch ($type) {
+                case 'id-at-countryName':
+                    $desc = 'C=';
+                    break;
+                case 'id-at-stateOrProvinceName':
+                    $desc = 'ST=';
+                    break;
+                case 'id-at-organizationName':
+                    $desc = 'O=';
+                    break;
+                case 'id-at-dnQualifier':
+                    $desc = 'OU=';
+                    break;
+                case 'id-at-commonName':
+                    $desc = 'CN=';
+                    break;
+                case 'id-at-localityName':
+                    $desc = 'L=';
+                    break;
+                default:
+                    $delim = '/';
+                    $desc = preg_replace('#.+-([^-]+)$#', '$1',  $type) . '=';
+            }
+
+            if (!$start) {
+                $output.= $delim;
+            }
+            $output.= $desc . $value;
+            $start = false;
+        }
+
+        return $output;
+    }
+
+    /**
+     * Set public key
+     *
+     * Key needs to be a Crypt_RSA object
+     *
+     * @param Object $key
+     * @access public
+     * @return Boolean
+     */
+    function setPublicKey($key)
+    {
+        $this->publicKey = $key;
+    }
+
+    /**
+     * Set private key
+     *
+     * Key needs to be a Crypt_RSA object
+     *
+     * @param Object $key
+     * @access public
+     * @return Boolean
+     */
+    function setPrivateKey($key)
+    {
+        $this->privateKey = $key;
+    }
+
+    /**
+     * Get the public key
      *
      * Keys need to be Crypt_RSA objects
      *
@@ -1640,9 +1791,9 @@ class File_X509 {
      * @access public
      * @return Boolean
      */
-    function setKey($key)
+    function getPublicKey($key)
     {
-        $this->key = $key;
+        $this->publicKey = $key;
     }
 
     /**
@@ -1685,14 +1836,224 @@ class File_X509 {
                 if (!class_exists('Crypt_RSA')) {
                     require_once('Crypt/RSA.php');
                 }
-                $this->key = new Crypt_RSA();
-                $this->key->loadKey($key);
+                $this->publicKey = new Crypt_RSA();
+                $this->publicKey->loadKey($key);
             default:
-                $this->key = NULL;
+                $this->publicKey = NULL;
         }
 
         $this->currentCert = $csr;
 
         return $csr;
     }
+
+    /**
+     * Sign an X.509 certificate
+     *
+     * $issuer's private key needs to be loaded.
+     * $subject can be either an existing X.509 cert (if you want to resign it),
+     * a CSR or something with the DN and public key explicitly set.
+     *
+     * @param Crypt_X509 $issuer
+     * @param Crypt_X509 $subject
+     * @param String $signatureAlgorithm optional
+     * @access public
+     * @return Mixed
+     */
+    function sign($issuer, $subject, $signatureAlgorithm = 'sha1WithRSAEncryption')
+    {
+        if (!is_object($issuer->privateKey) || !is_array($issuer->dn)) {
+            return false;
+        }
+
+        $currentCert = $this->currentCert;
+        $signatureSubject = $this->signatureSubject;
+
+        if (is_array($subject->currentCert) && isset($subject->currentCert['tbsCertificate'])) {
+            $this->currentCert = $subject->currentCert;
+            if (!empty($this->startDate)) {
+                $this->currentCert['tbsCertificate']['validity']['notBefore']['utcTime'] = $this->startDate;
+                unset($this->currentCert['tbsCertificate']['validity']['notBefore']['generalTime']);
+            }
+            if (!empty($this->endDate)) {
+                $this->currentCert['tbsCertificate']['validity']['notAfter']['utcTime'] = $this->endDate;
+                unset($this->currentCert['tbsCertificate']['validity']['notAfter']['generalTime']);
+            }
+            if (!empty($this->dn)) {
+                $this->currentCert['tbsCertificate']['subject'] = $this->dn;
+            }
+            $this->removeExtension('id-ce-authorityKeyIdentifier');
+            
+        } else {
+            $startDate = empty($this->startDate) ? $this->startDate : @date('M j H:i:s Y T');
+            $endDate = empty($this->endDate) ? $this->endDate : @date('M j H:i:s Y T', strtotime('+1 year'));
+            $serialNumber = empty($this->serialNumber) ? $this->serialNumber : "\0";
+
+            $this->currentCert = array(
+	        'tbsCertificate' =>
+                    array(
+                        'version' => 'v3',
+                        'serialNumber' => $this->serialNumber, // $this->setserialNumber()
+                        'signature' => $signatureAlgorithm,
+                        'issuer' => false, // this is going to be overwritten later
+                        'validity' => array(
+                            'notBefore' => array('utcTime' => $this->startDate), // $this->setStartDate()
+                            'notAfter' => array('utcTime' => $this->endDate)   // $this->setEndDate()
+                        ),
+                        'subject' => $subject->dn,
+                        'subjectPublicKeyInfo' => $subject->publicKey->getPublicKey()
+                    ),
+                 'signatureAlgorithm' => $signatureAlgorithm,
+                 'signature'          => false // this is going to be overwritten later
+            );
+        }
+
+        $this->currentCert['tbsCertificate']['issuer'] = $issuer->dn;
+
+        $this->loadX509($this->saveX509($this->currentCert));
+
+        $result = $this->_sign($issuer->privateKey, $signatureAlgorithm);
+
+        $this->currentCert = $currentCert;
+        $this->signatureSubject = $signatureSubject;
+
+        return $result;
+    }
+
+    /**
+     * X.509 certificate signing helper function.
+     *
+     * @param Object $key
+     * @param Crypt_X509 $subject
+     * @param String $signatureAlgorithm
+     * @access public
+     * @return Mixed
+     */
+    function _sign($key, $signatureAlgorithm)
+    {
+        switch (strtolower(get_class($key))) {
+            case 'crypt_rsa':
+                switch ($signatureAlgorithm) {
+                    case 'md2WithRSAEncryption':
+                    case 'md5WithRSAEncryption':
+                    case 'sha1WithRSAEncryption':
+                    case 'sha224WithRSAEncryption':
+                    case 'sha256WithRSAEncryption':
+                    case 'sha384WithRSAEncryption':
+                    case 'sha512WithRSAEncryption':
+                        $key->setHash(preg_replace('#WithRSAEncryption$#', '', $signatureAlgorithm));
+                        $key->setSignatureMode(CRYPT_RSA_SIGNATURE_PKCS1);
+
+                        $this->currentCert['signature'] = base64_encode("\0" . $key->sign($this->signatureSubject));
+
+                        return $this->currentCert;
+                }
+            default:
+                return false;
+        }
+    }
+
+    /**
+     * Set certificate start date
+     *
+     * @param String $date
+     * @access public
+     */
+    function setStartDate($date)
+    {
+        $this->startDate = @date('M j H:i:s Y T', @strtotime($date));
+    }
+
+    /**
+     * Set certificate end date
+     *
+     * @param String $date
+     * @access public
+     */
+    function setEndDate($date)
+    {
+        $this->endDate = @date('M j H:i:s Y T', @strtotime($date));
+    }
+
+    /**
+     * Set Serial Number
+     *
+     * @param String $serial
+     * @access public
+     */
+    function setSerialNumber($serial)
+    {
+        $this->serialNumber = $serial;
+    }
+
+    /**
+     * Remove an Extension
+     *
+     * @param String $id
+     * @access public
+     * @return Boolean
+     */
+    function removeExtension($id)
+    {
+        if (!is_array($this->currentCert) || !isset($this->currentCert['tbsCertificate'])) {
+            return false;
+        }
+
+        $result = false;
+        $extensions = &$this->currentCert['tbsCertificate']['extensions'];
+        foreach ($extensions as $key => $value) {
+            if ($value['extnId'] == $id) {
+                unset($extensions[$key]);
+                $result = true;
+            }
+        }
+
+        $extensions = array_values($extensions);
+
+        return $result;
+    }
+
+    /**
+     * Get an Extension
+     *
+     * Returns the extension if it exists and false if not
+     *
+     * @param String $id
+     * @access public
+     * @return Mixed
+     */
+    function getExtension($id)
+    {
+        if (!is_array($this->currentCert) || !isset($this->currentCert['tbsCertificate'])) {
+            return false;
+        }
+
+        foreach ($this->currentCert['tbsCertificate']['extensions'] as $key => $value) {
+            if ($value['extnId'] == $id) {
+                return $value['extnValue'];
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Returns a list of all extensions in use
+     *
+     * @access public
+     * @return Array
+     */
+    function getExtensions()
+    {
+        if (!is_array($this->currentCert) || !isset($this->currentCert['tbsCertificate'])) {
+            return false;
+        }
+
+        $extensions = array();
+        foreach ($this->currentCert['tbsCertificate']['extensions'] as $extension) {
+            $extensions[] = $extension['extnId'];
+        }
+
+        return $extensions;
+    }
 }
\ No newline at end of file