http://dl.gi.de/handle/20.500.12116/23177 2026-07-23T22:33:35Z http://dl.gi.de/handle/20.500.12116/23196 Sanitizable signatures: how to partially delegate control for authenticated data Brzuska, Christina; Fischlin, Marc; Lehmann, Anja; Schröder, Dominique Brömme, Arslan; Busch, Christoph; Hühnlein, Detlef Sanitizable signatures have been introduced by Ateniese et al. (ESORICS 2005) and allow an authorized party, the sanitizer, to modify a predetermined part of a signed message without invalidating the signature. Brzuska et al. (PKC 2009) gave the first comprehensive formal treatment of the five security properties for such schemes. These are unforgeability, immutability, privacy, transparency and accountability. They also provide a modification of the sanitizable signature scheme proposed by Ateniese et al. such that it provably satisfies all security requirement. Unfortunately, their scheme comes with rather large signature sizes and produces computational overhead that increases with the number of admissible modifications. In this paper we show that by sacrificing the transparency property - thus allowing to distinguish whether a message has been sanitized or notwe can obtain a sanitizable signature scheme that is still provably secure concerning the other aforementioned properties but significantly more efficient. We propose a construction that is based solely on regular signature schemes, produces short signatures and only adds a small computational overhead. 2009-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/23193 Spectral selection for a biometric recognition system based on hand veins detection through image spectrometry Cortés, Franciso; Aranda, José M.; Sanchez-Reillo, Raul; Meléndez, Juan; López, Fernando Brömme, Arslan; Busch, Christoph; Hühnlein, Detlef This paper presents the result of a work orientated to the spectral optimization of the acquisition devices in vascular biometrics systems. Spectral windows are proposed which will allow to design a multispectral system with a few and well defined bands, obtaining a more robust and reliable device, compared with the standard single band systems. This is in accordance to general trend of electro-optical and infrared acquisition systems in the field of the detection and remote sensing, where the work focus is on obtaining optimized bands. To carry out this work a Hyperespectral Imaging System (HIS) has been used as the acquisition system. In order to analyze the large amount of information and to select the spectral bands, a Principal Component Analysis (PCA) has been done. 2009-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/23195 SAMLizing the European citizen card Eichholz, Jan; Hühnlein, Detlef; Schwenk, Jörg Brömme, Arslan; Busch, Christoph; Hühnlein, Detlef While the use of Federated Identity Management and Single Sign-On based on the Security Assertion Markup Language (SAML) standards becomes more and more important, there are quite a few European countries which are about to introduce national ID cards, which are compliant to the European Citizen Card (ECC) specification prTS 15480. The present contribution shows how these two seemingly opposite approaches may be integrated in a seamless and secure fashion such that it is possible to use the security features of the ECC in a federated scenario, which allows easy integration of Service Providers. 2009-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/23194 The extended access control for machine readable travel documents Chaabouni, Rafik; Vaudenay, Serge Brömme, Arslan; Busch, Christoph; Hühnlein, Detlef Machine Readable travel documents have been rapidly put in place since 2004. The initial standard was made by the ICAO and it has been quickly followed by the Extended Access Control (EAC). In this paper we discuss about the evolution of these standards and more precisely on the evolution of EAC. We intend to give a realistic survey on these standards. We discuss about their problems, such as the inexistence of a clock in the biometric passports and the absence of a switch preventing the lecture of a closed passport. We also look at the issue with retrocompatibility that could be easily solved and the issue with terminal revocation that is harder. 2009-01-01T00:00:00Z