These keyfobs number generators are actually pretty interesting devices. The basic principle is that they generate a pseudorandom sequence of numbers. The starting seed of each device is different, and each device's seed is known to the authenticating server. Given the initial seed and the current time, the server can predict what is the number that the token will show.
Due to the properties of the pseudorandom algo, it is impossible to guess the seed by observing a token's digits.
And these sealed tokens self-destruct if tampered with. No, you can't change the batteries. :)
Due to the properties of the pseudorandom algo, it is impossible to guess the seed by observing a token's digits.
And these sealed tokens self-destruct if tampered with. No, you can't change the batteries. :)