Niklas Büscher

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CAPTCHAs are small puzzles which should be easily solv-able by human beings but hard to solve for computers. They build a security cornerstone of the modern Internet service landscape, deployed in essentially any kind of login service, allowing to distinguish authorized human beings from automated attacks. One of the most popular and successful systems(More)
Practical hardness results are necessary to select parameters for cryptographic schemes. Cryptographic challenges proved to be useful for determining the practical hardness of computational problems that are used to build public-key cryptography. However, several of these problems have the drawback that it is not known how to create a challenge for them(More)
Interconnected embedded devices are increasingly used in various scenarios, including industrial control, building automation , or emergency communication. As these systems commonly process sensitive information or perform safety critical tasks, they become appealing targets for cyber attacks. A promising technique to remotely verify the safe and secure(More)
AIM To characterize major determinants of 20-year survival after liver transplantation (LT). METHODS This longitudinal single-institution study includes 313 consecutive patients who received a LT between 1988 and 1992. Pretransplant clinical characteristics and laboratory values were assessed and compared between 20-year survivors and non-survivors.(More)
Secure two-party computation (TPC) based on Yao's garbled circuits has seen a lot of progress over the past decade. Yet, compared with generic computation, TPC is still multiple orders of magnitude slower. To improve the efficiency of secure computation based on Yao's protocol, we propose a practical parallelization scheme. Its advances over existing(More)
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