Code to encrypt and store salted usernames and passwords in PHP using MCrypt from http://jeffreifman.com/filtered-open-source-imap-mail-filtering-software-for-php/

gistfile1.txt

   public function createCredentials($username,$password) {
     $salt = $this->random_string(4,4).'::'.$this->random_string(4,4);
     $salts = explode('::',$salt);
     $str = $salts[0].'::'.$username.'::'.$password.'::'.$salts[1];
     $td = mcrypt_module_open('tripledes', '', 'ecb', '');
     $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
     $account_salt = Yii::app()->params['account_salt'];     // stored in your ini file somewhere on your server
     mcrypt_generic_init($td, $account_salt, $iv);
     $encrypted_data = mcrypt_generic($td, $str);
     mcrypt_generic_deinit($td);
     mcrypt_module_close($td);
     $result = array($salt,$encrypted_data);
     return $result;
   }
      
   public function getCredentials($cred) {     
     $account_salt = Yii::app()->params['account_salt'];     
     $cred = base64_decode($cred);
     $td = mcrypt_module_open('tripledes', '', 'ecb', '');
     $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
     mcrypt_generic_init($td, $account_salt, $iv);
     $result = mdecrypt_generic($td,$cred);
     mcrypt_generic_deinit($td);
     mcrypt_module_close($td);
     $cred = explode('::',$result);
     array_shift($cred);
     array_pop($cred);   
     return $cred;
   }
   
   public function random_string($num_characters=5,$num_digits=3)
   {
     // via http://salman-w.blogspot.com/2009/06/generate-random-strings-using-php.html
       $character_set_array = array();
       $character_set_array[] = array('count' => $num_characters, 'characters' => 'abcdefghijklmnopqrstuvwxyz');
       $character_set_array[] = array('count' => $num_digits, 'characters' => '0123456789');
       $temp_array = array();
       foreach ($character_set_array as $character_set) {
           for ($i = 0; $i < $character_set['count']; $i++) {
               $temp_array[] = $character_set['characters'][rand(0, strlen($character_set['characters']) - 1)];
           }
       }
       shuffle($temp_array);
       return implode('', $temp_array);
   }