[HGI-News-de] HGI Kolloquium Do. 16.07.: "Twin Signature Schemes, Revisited" von S. Schäge

[Newsletter des Horst Görtz Instituts]

Hallo,

im Rahmen des HGI Kolloquiums "Aktuelle Themen der IT-Sicherheit" wird
am kommenden *Donnerstag* der folgende Vortrag angeboten:

Sven Schäge (Lehrstuhl NDS):
*Twin Signature Schemes, Revisited*

Termin:
Donnerstag, der 16. Juli um  11.00 Uhr (*s.t.*)
Raum: IC 4/161

Interessierte sind herzlich eingeladen!


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Abstract:

In this paper, we revisit the twin signature scheme by Naccache,
Pointcheval and Stern from CCS 2001 that is secure under the Strong RSA
(SRSA) assumption and improve its efficiency in several ways. First, we
present a new twin signature scheme that is based on the Strong
Diffie-Hellman (SDH) assumption in bilinear groups. Since bilinear
groups can, at the same level of security, have a much compacter group
representation than RSA groups, the new scheme allows for very short
signatures and key material. Another advantage of the SDH based scheme
is that, in contrast to the original scheme, it does not require a
computationally expensive function which injectively maps messages to
primes. We prove this new scheme secure under adaptive chosen message
attacks. Second, we present a modification that allows to significantly
increase efficiency when signing long messages. This construction uses
collision-resistant hash functions as its basis. As a result, our
improvements make the signature length independent of the message size.
Our construction deviates from the standard hash-and-sign approach in
which the hash value of the message is signed in place of the message
itself. We show that in the case of twin signatures, one can exploit the
collision-resistance property of the hash function as an integral part
of the signature scheme. This improvement can be applied to both the
SRSA based and SDH based twin signature scheme.
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Informationen über die nächsten geplanten Vorträge im Rahmen des
HGI Kolloquiums sind auch im Web zu finden:
http://www.hgi.rub.de/hgi/hgi-seminar/aktuelles

Gruß,
Mathias Herrmann