It is my suspicion that seeds which depend on machine states(ie state of your computer at a specific instance of time) would always be subject to scrutiny and de-cryption. As long as the software used to encrypt is not self-modifying, the machine state can (through careful manipulation involving temperature, clocks, processes etc)always be replicated and fixed to an acceptable degree. This allows you to look into the heart of the encryption method and then create a plan to decode based on a brute-force attack. Time is the only friend then of the encryptor and unfortunately in the case of credit cards this typically is measured in years. Plenty of time for brute force attacks to yield fruit. I'll be gone for two days. will respond to any comments Saturday.