Dr. Ron Steinfeld
Macquarie University
Title: How to Strengthen any Weakly Unforgeable Signature into a
Strongly Unforgeable Signature
Standard signature schemes are usually designed only to achieve
weak unforgeability, preventing forgery of signatures on
new messages not previously signed. However, some applications
require strong unforgeability, preventing also forgery of
new signatures on previously signed messages. Motivated by such
applications, we present a general transform for strengthening a given
weakly unforgeable signature into a strongly unforgeable signature
using a trapdoor hash function. We also review other such
transforms proposed in the literature.