USB Security Token

[Seyrena]

Mathematical-algorithm-based one-time passwords
Another type of one-time password uses a complex mathematical algorithm, such as a hash chain, to generate a series of one-time passwords from a secret shared key. Each password is unguessable, even when previous passwords are known. The open source OATH algorithm is standardized; other algorithms are covered by U.S. patents. Each new password is unique, so an unauthorized user would be unable to guess what the new password may be, based on previously used passwords.


It cant be broken. This came straight from Wikipedia

The Blizzard Authenticator was cracked.

[Meyi]

I personally think this is a decent, interesting idea.