Patent ID: 7337322
Filing Date: 2008-02-26
Classification: H04L

Abstract:
1. A method of generating and verifying a digital signature of a message between a sender and a recipient, wherein the sender is m+1 levels below a root PKG in a hierarchical system including a plurality of PKGs, the plurality of PKGs including at least the root PKG and m lower-level PKGs in the hierarchy between the root PKG and the sender, wherein m≧1, the method comprising: selecting a root key generation secret that is known only to the root PKG; generating a root key generation parameter based on the root key generation secret; generating a lower-level key generation secret for each of the m lower-level PKGs, wherein each lower-level key generation secret is known only to its associated lower-level PKG; generating a lower-level key generation parameter for each of the m lower-level PKGs, wherein each lower-level key generation parameter is generated using at least the lower-level key generation secret for its associated lower-level PKG; generating a sender private key for the sender such that the sender private key is related to at least sender identity information, the root key generation secret, and one or more of the m lower-level key generation secrets associated with the m lower-level PKGs in the hierarchy between the root PKG and the sender; signing the message to generate the digital signature using at least the sender private key; and verifying the digital signature using at least the root key generation parameter and the sender identity information.