Browse Prior Art Database

File expiration

IP.com Disclosure Number: IPCOM000180473D
Original Publication Date: 2009-Mar-10
Included in the Prior Art Database: 2009-Mar-10
Document File: 1 page(s) / 25K

Publishing Venue

Lenovo

Abstract

Disclosed is a means of expiring the ability for a file to be used after a given date, using encryption.

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File expiration

Disclosed is a means of expiring the ability for a file to be used after a given date, using encryption.

Disclosed is a means of setting a data after which a document will not be usable on a system, because it will no longer be decryptable.  The problem is control of data inside an enterprise. In particular, providing "expiration dates" to documents so that after a particular time, a file is no longer available for use. A solution to this has general applicability to things like expiration of movies downloaded over the web, etc. Additionally, a VM could be given to a contractor, and "expire" so that it can no longer be used after the contractors contract expires.

The solution to this uses the TPM, by having a date and random number R stored in a NVRAM location which is only readable during the early boot sequence (by being locked to PCRs that get extended later in the boot sequence).  The BIOS checks this date during boot, and if the current date is earlier than this expiration date, it extends a R into a

PCR

location.  This R allows the encryption key that will be used to decrypt a document to be read from the TPM, so the document can be read.