Krzysztof Majcher

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HB and HB+ are a shared secret-key authentication protocols designed for low-cost devices such as RFID tags. HB+ was proposed by Juels and Weis at Crypto 2005. The security of the protocols relies on the learning parity with noise (LPN) problem, which was proven to be NP-hard. The best known attack on LPN by Levieil and Fouque [13] requires subexponential(More)
In this paper we present methods of protecting RFID tags users' privacy. Based on well-known technique by Juels et al. called Blocker tag we introduce a set of methods for increasing security using a device called Hedgehog blocker. Hedgehog blocker copes with the problem of the additional information gained by the adversary through measuring signal power(More)
In this paper we introduce a new approach for RFID users' privacy protection that is in some sense complementary to well-known blocker tag due to Juels et al. The main idea behind our scheme is to add a special device called allower to a batch of tags in order to make reading RFID-tags possible. When the allower is switched-off reading is not possible. From(More)
We present an authentication scheme designed for tiny and strictly constrained devices like RFID-tags. Authentication is based on the symmetric key shared between a tag and a reader. While a tag needs to perform only simple operations in order to authenticate: to pick n/2+b random values and then to compute XORs of some values, a reader needs to try 2(More)
Recently, the need for efficient representations of data conveyed by graphical structures has emerged in many different contexts. While compressing such data one must consider two types of information. The first type is the information carried by the labels embedded in the structure. The second type is the information conveyed by the structure itself. In(More)
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