From 564741f77b5203d3d54ec14e32d25c87028ecd7f Mon Sep 17 00:00:00 2001
From: alecpl <alec@alec.pl>
Date: Tue, 31 Aug 2010 18:39:32 +0000
Subject: - performance: use custom function for IV vector generation instead
 of mcrypt_create_iv()

---
 program/include/rcmail.php | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index 980379075..808f0db06 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -1071,7 +1071,7 @@ class rcmail
     if (function_exists('mcrypt_module_open') &&
         ($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, "")))
     {
-      $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
+      $iv = $this->create_iv(mcrypt_enc_get_iv_size($td));
       mcrypt_generic_init($td, $this->config->get_crypto_key($key), $iv);
       $cipher = $iv . mcrypt_generic($td, $clear);
       mcrypt_generic_deinit($td);
@@ -1082,9 +1082,7 @@ class rcmail
 
       if (function_exists('des')) {
         $des_iv_size = 8;
-        $iv = '';
-        for ($i = 0; $i < $des_iv_size; $i++)
-          $iv .= sprintf("%c", mt_rand(0, 255));
+        $iv = $this->create_iv($des_iv_size);
         $cipher = $iv . des($this->config->get_crypto_key($key), $clear, 1, 1, $iv);
       }
       else {
@@ -1152,6 +1150,22 @@ class rcmail
     return $clear;
   }
 
+  /**
+   * Generates encryption initialization vector (IV)
+   *
+   * @param int Vector size
+   * @return string Vector string
+   */
+  private function create_iv($size)
+  {
+    // mcrypt_create_iv() can be slow when system lacks entrophy
+    // we'll generate IV vector manually
+    $iv = '';
+    for ($i = 0; $i < $size; $i++)
+        $iv .= chr(mt_rand(0, 255));
+    return $iv;
+  }
+
   /**
    * Build a valid URL to this instance of RoundCube
    *
-- 
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