Detlef Hühnlein

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We introduce a new cryptosystem with trapdoor decryption based on the di culty of computing discrete logarithms in the class group of the non maximal imaginary quadratic order O q where q q square free and q prime The trapdoor information is the conductor q Knowledge of this trapdoor information enables one to switch to and from the class group of the(More)
We present a new non-interactive public-key distribution system based on the class group of a non-maximal imaginary quadratic order ClðDpÞ. The main advantage of our system over earlier proposals based on ðZ=nZÞ [25,27] is that embedding id information into group elements in a cyclic subgroup of the class group is easy (straight-forward embedding into prime(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)
Several European countries currently introduce highly sophisticated eID functionality in their national identity cards. This functionality typically has no direct relation to web security standards, but will be integrated with web technologies to enable browser-based access to critical resources. The research challenge to combine eID protocols and web(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)
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)
In and there are proposed ElGamal type cryptosys tems based on non maximal imaginary quadratic orders with fast trap door decryption The trapdoor information is the factorization of the non fundamental discriminant q q We will extend the ideas given there to set up Rabin and RSA analogues based on non maximal imagi nary quadratic orders To implement the(More)
In this work, we discuss the diffusion of federated identity management. We base our research on Roger’s diffusion of innovation theory, and derive generic factors influencing the diffusion of federated identity management solutions. To validate our model and investigate specific contributions of parameters in specific usage scenarios, we investigate market(More)