Detlef Hühnlein

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We i n troduce a new cryptosystem with trapdoor decryption based on the diiculty of computing discrete logarithms in the class group of the non-maximal imaginary quadratic order O q , where q = q 2 , square-free and q prime. The trapdoor information is the conductor q. Knowledge of this trapdoor information enables one to switch t o a n d from the class(More)
We present a new non-interactive public-key distribution system based on the class group of a non-maximal imaginary quadratic order ClðD p Þ. The main advantage of our system over earlier proposals based on ðZ=nZÞ Ã [25,27] is that embedding id information into group elements in a cyclic subgroup of the class group is easy (straightforward embedding into(More)
Federated Single-Sign-On using web browsers as User Agents becomes increasingly important. However, current proposals require substantial changes in the implementation of the Relying-Party, and concentrate on functionality rather than security against real-world attacks like Cross Site Scripting (XSS) and Pharming. We therefore propose a different approach(More)
—It is well known that the suitability of many cryptographic algorithms decreases with time. Hence, it is a challenging task to maintain the integrity, authenticity, confidentiality and availability of sensitive data over very long periods of time. A scalable approach to preserve the integrity and authenticity of archived data has been standardized in [12].(More)
The paper at hand discusses the design and implementation of the " Open eCard App " , which is a lightweight and open eID client, which integrates major international standards. It supports strong authentication and electronic signatures with numerous common electronic identity cards in desktop as well as mobile environments. The Open eCard App is designed(More)
Many future electronic identity cards will be equipped with a contact-less interface. Analysts expect that a significant proportion of future mobile phones support Near Field Communication (NFC) technology. Thus, it is a reasonable approach to use the cell phone as mobile smart card terminal, which in particular supports the Password Authenticated(More)
Since nobody can guarantee that the computation of discrete logarithms in elliptic curves or IF p remains intractible for the future it is important to study cryptosystems based on alternative groups. A promising candidate, which was proposed by Buch-mann and Williams 8], is the class group C l(() of an imaginary quadratic order O. This ring is isomorphic(More)