The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 09, 2011
Filed:
Nov. 30, 2004
William M. Shapiro, Palo Alto, CA (US);
William M. Shapiro, Palo Alto, CA (US);
Adobe Systems Incorporated, San Jose, CA (US);
Abstract
Systems and techniques relating to cryptographic keys include, in one implementation, a technique involving: generating a symmetric encryption key; and generating from the symmetric encryption key a family of symmetric encryption keys having a relationship such that a descendent key of the family is derivable from each key that is an ancestor of the descendent key in the family. Generating the family of symmetric encryption keys can involve cryptographically hashing the original symmetric encryption key and resulting hashed encryption keys. The technique can further include rolling over a key used in securing information by providing a next symmetric encryption key of the family in an order opposite that of an order of key generation; and a client can cryptographically hash a first symmetric encryption key to produce a second symmetric encryption key of the family and decrypt information associated with an electronic document with the key thus produced.