Encrypt and decrypt cookie

Hi, I am using libmcrypt-2.5.3 to do encryption in php. I use exactly the steps provided in mcrypt_module_open available on php website http://php.benscom.com/manual/en/function.mcrypt-module-open.php I can encrypt and decrypt a string correctly. However, if i encrypt a cookie to write to user's browser, the decryption is incorrect when i try to decrypt this cookie when user comes again. I found out the main cause is the function mcrypt_module_open. This function return a different resource everytime it is called. Eventually it cause the decryption on cookie to be incorrect. Can someone give me suggestion on how to encrypt and decrypt a cookie? Thanks very much. Kim __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com