Patent Monkey: Tivo Locks, Takes Key to Your HD

, TiVo describes use of an encryption key technique that has so many possible combinations that the ability to crack it could take billions of years of number crunching.

TiVo has developed technology to create a link between a host and a local hard drive using an encryption key to lock down any access by you, the user, unless the code can be correctly identified. This concept builds upon the commonly used technique of a Universally Unique Identifiers (UUIDs) that are created with so many possible combinations “that 1 trillion UUIDs have to be created every nanosecond for 10 billion years to exhaust the number of UUIDs.”

While UUIDs are a general technique, TiVo describes using the SHA-1 algorithm described in the Secure Hash Standard, Federal Information Processing Standard 180-1, National Institute of Standards and Technology (Apr. 17, 1995), that is, if you’re interested in light reading. In short, guessing the key is no easy task.

Specifically, TiVo’s invention is a method of locking down a hard drive or peripheral from a user through use of an complex encryption key baring local access. In short, content on your drive is yours to use, the way TiVo intends it. From the patent:

The drive/host system’s basic requirement is that both the drive controller and the host computer, or some peripheral attached thereto, are capable of storing a small amount of key information (roughly 1024 bits in the presently preferred embodiment of the invention). On the disk drive, a disk drive controller is used for generating random challenges and comparing response values. On the host, a cryptography chip is used to challenge and lock information and to run the SHA-1 algorithm on this information to produce a response value. For adequate security, it is necessary that the key storage, and the calculation of the SHA-1 hash values, be performed in a way which prevents the key information from being viewed or copied by an external user.

While the new patent obviousness standard may make this patent harder to enforce, use of this technique may make ripping content from your TiVo quite a popular Digg story.

TiVo Awarded Patent For Password [Davis Freeberg’s Digital Connection]