Abstract. The design of lightweight block ciphers has been a very active research topic over the last years. However, the lack of comparative source codes generally makes it hard to evaluate the extent to which implementations of different ciphers actually reach their low-cost goals on various platforms. This paper reports on an initiative aiming to relax this issue. First, we provide implementations of 12 block ciphers on an ATMEL AVR ATtiny45 8-bit microcontroller, and make the corresponding source code available on a web page. All implementations are made public under an open-source license. Common interfaces and design goals are followed by all designers to achieve comparable implementation results. Second, we evaluate performance figures of our implementations with respect to different metrics, including energy-consumption measurements and show our improvements compared to existing implementations.

Most advanced security systems rely on public-key schemes based either on the factorization or the discrete logarithm problem. Since both problems are known to be closely related, a major breakthrough in cryptanalysis tackling one of those problems could render a large set of cryptosystems completely useless. The McEliece public-key scheme is based on the alternative security assumption that decoding unknown linear binary codes is NP-complete. In this work, we investigate the efficient implementation of the McEliece scheme on embedded systems what was-up to date-considered a challenge due to the required storage of its large keys. To the best of our knowledge, this is the first time that the McEliece encryption scheme is implemented on a low-cost 8-bit AVR microprocessor and a Xilinx Spartan-3AN FPGA.

Abstract. We propose a new authentication protocol that is provably secure based on a ring variant of the learning parity with noise (LPN) problem. The protocol follows the design principle of the LPN-based protocol from Eurocrypt'11 (Kiltz et al.), and like it, is a two round protocol secure against active attacks. Moreover, our protocol has small communication complexity and a very small footprint which makes it applicable in scenarios that involve low-cost, resourceconstrained devices.Performance-wise, our protocol is more efficient than previous LPN-based schemes, such as the many variants of the Hopper-Blum (HB) protocol and the aforementioned protocol from Eurocrypt'11. Our implementation results show that it is even comparable to the standard challenge-and-response protocols based on the AES block-cipher. Our basic protocol is roughly 20 times slower than AES, but with the advantage of having 10 times smaller code size. Furthermore, if a few hundred bytes of non-volatile memory are available to allow the storage of some off-line pre-computations, then the online phase of our protocols is only twice as slow as AES.

Abstract. In the last years code-based cryptosystems were established as promising alternatives for asymmetric cryptography since they base their security on well-known NP-hard problems and still show decent performance on a wide range of computing platforms. The main drawback of code-based schemes, including the popular proposals by McEliece and Niederreiter, are the large keys whose size is inherently determined by the underlying code. In a very recent approach, Misoczki et al. proposed to use quasi-cyclic MDPC (QC-MDPC) codes that allow for a very compact key representation. In this work, we investigate novel implementations of the McEliece scheme using such QC-MDPC codes tailored for embedded devices, namely a Xilinx Virtex-6 FPGA and an 8-bit AVR microcontroller. In particular, we evaluate and improve different approaches to decode QC-MDPC codes. Besides competitive performance for encryption and decryption on the FPGA, we achieved a very compact implementation on the microcontroller using only 4,800 and 9,600 bits for the public and secret key at 80 bits of equivalent symmetric security.

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