[HGI-News] HGI Seminar 31.10.2005

[Newsletter des Horst Görtz Instituts]

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                               Carlos Coronado
                      Technical University of Darmstadt

                   The Merkle multi-time signature scheme:
                 Its security, efficiency and improvements.

                   Montag, 31.10.2005, 13:15 Uhr, IC 4/39


Abstract

Signature schemes based on RSA or ElGamal schemes are not secure, if
integer factorization or solving the discrete logarithm problem are
computationally feasible.  There exists a quantum algorithm which
solves these problems in polynomial time.  Even though there are no
quantum computers yet, it is important to provide secure and efficient
signature schemes whose security is based on other problems.

In the late 70's Merkle proposed a multi-time signature scheme.
Basically, his scheme transforms a one-time signature scheme into a
multi-time one.  Since one-time signature schemes can be built from
hash functions, their security and the security of Merkle's scheme can
be reduced to the cryptographic properties of the underlying hash
function.

In this talk we present our improvements to this scheme and sketch the
proofs of their security.  We end by showing some experimental
results.


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Next talks:

07.11.2005  Gregor Leander. Title TBA.
21.11.2005  Michael Tuexen. Title TBA.

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Prof. Dr. Roberto Avanzi
Faculty for Mathematics
Ruhr-University Bochum
44780 Bochum, Germany

URL:   http://www.cits.rub.de
         http://www.rub.de/hgi


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