Quote Originally Posted by wildsprite View Post

as for vulnerability, they would need to figure out the algorithm of your token,
The algorithm is already known, it uses either DES 3DES or AES depending on the customer's (Square Enix in this case) preference, though idk why you would use anything other than AES. Good encryption doesn't rely on keeping the algorithm secret to ensure security, it relies on being mathematically difficult to break. Also unlike something like a Blu-ray disk (which has encrypted data that has to work with multiple devices and therefor has to use a single common key) they can use a unique key for each token so even if someone were to mount a brute force attack on one they would only get the key for that individual token, and this would take years to decades anyway.