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Seminars given
May 27, 2003 - Transitive signatures based on factoring and RSA
by Gregory Neven
| Abstract: | Transitive signatures are a special flavor of digital signatures in
which the signer authenticates a dynamically growing graph by signing
edges between nodes, with the additional property that given two
signatures for adjacent edges {i,j} and {j,k}, anyone can compute a
third signature for the direct connection {i,k} without needing the
signer's help.
Micali and Rivest introduced the concept of transitive signatures and
proposed a first realization based on the hardness of discrete
logarithms. In this presentation, we'll introduce a new scheme based on
the hardness of factoring large composite integers, and we answer an
open question raised by Micali and Rivest regarding the security of an
RSA-based scheme by proving it transitively unforgeable under adaptive
chosen-message attack assuming the hardness of the hardness of the
one-more RSA problem. Finally, we present hash-based modifications of
these schemes that are provably secure in the random oracle model and
that result in performance improvements.
This is joint work with Mihir Bellare from University of California at
San Diego and has been published at ASIACRYPT 2002 (paper available at
http://www.cs.kuleuven.ac.be/~gregory/ts.ps). |
