From a8863e2b3deceec209876bec5873a6b5d0594f90 Mon Sep 17 00:00:00 2001
From: Jim Wigginton <terrafrost@php.net>
Date: Sun, 29 Aug 2010 03:27:02 +0000
Subject: [PATCH] - included a work-around for a bug in Portable OpenSSH 4.4
 and earlier whereby faulty key sizes are used for aes256-ctr, aes192-ctr and
 arcfour256 (thanks, f.dammassa!)

git-svn-id: http://phpseclib.svn.sourceforge.net/svnroot/phpseclib/trunk@116 21d32557-59b3-4da0-833f-c5933fad653e
---
 phpseclib/Net/SSH2.php | 49 +++++++++++++++++++++++++++++++++---------
 1 file changed, 39 insertions(+), 10 deletions(-)

diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index cee090ae..a78f9480 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -60,7 +60,7 @@
  * @author     Jim Wigginton <terrafrost@php.net>
  * @copyright  MMVII Jim Wigginton
  * @license    http://www.gnu.org/licenses/lgpl.txt
- * @version    $Id: SSH2.php,v 1.49 2010-08-28 17:26:22 terrafrost Exp $
+ * @version    $Id: SSH2.php,v 1.50 2010-08-29 03:27:02 terrafrost Exp $
  * @link       http://phpseclib.sourceforge.net
  */
 
@@ -563,6 +563,23 @@ class Net_SSH2 {
      */
     var $signature_format = '';
 
+    /**
+     * Key size fix
+     *
+     * Portable OpenSSH 4.4 and earlier use faulty key sizes for aes256-ctr, aes192-ctr and arcfour256.
+     * These algorithms could be removed from $encryption_algorithms in Net_SSH2::_key_exchange() but we'll
+     * adjust the key sizes instead to confirm that the version detection technique we're using is correct.
+     * If it isn't correct than we'll get decryption / encryption errors.  We wouldn't get any errors, in
+     * contrast, if the algorithms were simply removed, and would never know if the version detection
+     * technique we were using was correct.
+     *
+     * @link http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/ssh2-aesctr-openssh
+     * @see Net_SSH2::Net_SSH2()
+     * @var Boolean
+     * @access private
+     */
+    var $adjust_key_fix = false;
+
     /**
      * Default Constructor.
      *
@@ -708,6 +725,8 @@ class Net_SSH2 {
             return;
         }
 
+        $this->adjust_key_fix = preg_match('#SSH-' . $matches[1] . '\-OpenSSH_([\d\.]+)#', $this->server_identifier, $matches) && $matches[1] < 4.6;
+
         fputs($this->fsock, $this->identifier . "\r\n");
 
         $response = $this->_get_binary_packet();
@@ -866,12 +885,16 @@ class Net_SSH2 {
                 $decryptKeyLength = 24; // eg. 192 / 8
                 break;
             case 'aes256-cbc':
-            case 'aes256-ctr':
                 $decryptKeyLength = 32; // eg. 256 / 8
                 break;
+            case 'aes256-ctr':
+                $decryptKeyLength = !$this->adjust_key_fix ? 32 : 16;
+                break;
             case 'aes192-cbc':
+                $decryptKeyLength = 24;
+                break;
             case 'aes192-ctr':
-                $decryptKeyLength = 24; // eg. 192 / 8
+                $decryptKeyLength = !$this->adjust_key_fix ? 24 : 16;
                 break;
             case 'aes128-cbc':
             case 'aes128-ctr':
@@ -879,10 +902,10 @@ class Net_SSH2 {
                 break;
             case 'arcfour':
             case 'arcfour128':
-                $decryptKeyLength = 16; // eg. 128 / 8
+                $decryptKeyLength = 16;
                 break;
             case 'arcfour256':
-                $decryptKeyLength = 32; // eg. 128 / 8
+                $decryptKeyLength = !$this->adjust_key_fix ? 32 : 16;
                 break;
             case 'none';
                 $decryptKeyLength = 0;
@@ -901,13 +924,17 @@ class Net_SSH2 {
                 $encryptKeyLength = 24;
                 break;
             case 'aes256-cbc':
-            case 'aes256-ctr':
                 $encryptKeyLength = 32;
                 break;
+            case 'aes256-ctr':
+                $encryptKeyLength = !$this->adjust_key_fix ? 32 : 16;
+                break;
             case 'aes192-cbc':
-            case 'aes192-ctr':
                 $encryptKeyLength = 24;
                 break;
+            case 'aes192-ctr':
+                $encryptKeyLength = !$this->adjust_key_fix ? 24 : 16;
+                break;
             case 'aes128-cbc':
             case 'aes128-ctr':
                 $encryptKeyLength = 16;
@@ -917,7 +944,7 @@ class Net_SSH2 {
                 $encryptKeyLength = 16;
                 break;
             case 'arcfour256':
-                $encryptKeyLength = 32;
+                $encryptKeyLength = !$this->adjust_key_fix ? 32 : 16;
                 break;
             case 'none';
                 $encryptKeyLength = 0;
@@ -1408,7 +1435,7 @@ class Net_SSH2 {
                 for ($i = 0; $i < $num_prompts; $i++) {
                     extract(unpack('Nlength', $this->_string_shift($response, 4)));
                     // prompt - ie. "Password: "; must not be empty
-                    $this->_string_shift($response, $length); // prompt; must not be empty
+                    $this->_string_shift($response, $length);
                     $echo = $this->_string_shift($response) != chr(0);
                 }
                 */
@@ -1418,9 +1445,10 @@ class Net_SSH2 {
                    MUST respond with an SSH_MSG_USERAUTH_INFO_RESPONSE message.
                 */
                 // see http://tools.ietf.org/html/rfc4256#section-3.4
-                $packet = pack('CN', NET_SSH2_MSG_USERAUTH_INFO_RESPONSE, count($responses));
+                $packet = $logged = pack('CN', NET_SSH2_MSG_USERAUTH_INFO_RESPONSE, count($responses));
                 for ($i = 0; $i < count($responses); $i++) {
                     $packet.= pack('Na*', strlen($responses[$i]), $responses[$i]);
+                    $logged.= pack('Na*', strlen('dummy-answer'), 'dummy-answer');
                 }
 
                 if (!$this->_send_binary_packet($packet)) {
@@ -1429,6 +1457,7 @@ class Net_SSH2 {
 
                 if (defined('NET_SSH2_LOGGING')) {
                     $this->message_number_log[count($this->message_number_log) - 1] = 'NET_SSH2_MSG_USERAUTH_INFO_RESPONSE';
+                    $this->message_log[count($this->message_log) - 1] = $logged;
                 }
 
                 /*