A method of generating digital signatures for signing an infinitely expandable series of messages M.sub.i. An infinitely expandable tree of signature nodes is used, where each node can be used to sign a message. Each node is also used to sign up to k subnodes, where k is an integer greater than one....http://www.google.com.au/patents/US4881264?utm_source=gb-gplus-sharePatent US4881264 - Digital signature system and method based on a conventional encryption function
