Fischlin, Marc; Lehmann, Anja; Pietrzak, Krzysztof ZIST Austria
A robust multi-property combiner for a set of security properties merges two hash functions such that the resulting function satisfies each of the properties which at least one of the two starting functions has. Fischlin and Lehmann (TCC 2008) recently constructed a combiner which simultaneously preserves collision-resistance, target collision-resistance, message authentication, pseudorandomness and indifferentiability from a random oracle (IRO). Their combiner produces outputs of 5n bits, where n denotes the output length of the underlying hash functions. In this paper we propose improved combiners with shorter outputs. By sacrificing the indifferentiability from random oracles we obtain a combiner which preserves all of the other aforementioned properties but with output length 2n only. This matches a lower bound for black-box combiners for collision-resistance as the only property, showing that the other properties can be achieved without penalizing the length of the hash values. We then propose a combiner which also preserves the IRO property, slightly increasing the output length to 2n + ω(logn). Finally, we show that a twist on our combiners also makes them robust for one-wayness (but at the price of a fixed input length).
655 - 666
ICALP: Automata, Languages and Programming
Fischlin M, Lehmann A, Pietrzak KZ. Robust multi property combiners for hash functions revisited. In: Vol 5126. Springer; 2008:655-666. doi:10.1007/978-3-540-70583-3_53
Fischlin, M., Lehmann, A., & Pietrzak, K. Z. (2008). Robust multi property combiners for hash functions revisited (Vol. 5126, pp. 655–666). Presented at the ICALP: Automata, Languages and Programming, Springer. https://doi.org/10.1007/978-3-540-70583-3_53
Fischlin, Marc, Anja Lehmann, and Krzysztof Z Pietrzak. “Robust Multi Property Combiners for Hash Functions Revisited,” 5126:655–66. Springer, 2008. https://doi.org/10.1007/978-3-540-70583-3_53.
M. Fischlin, A. Lehmann, and K. Z. Pietrzak, “Robust multi property combiners for hash functions revisited,” presented at the ICALP: Automata, Languages and Programming, 2008, vol. 5126, no. PART 2, pp. 655–666.
Fischlin M, Lehmann A, Pietrzak KZ. 2008. Robust multi property combiners for hash functions revisited. ICALP: Automata, Languages and Programming, LNCS, vol. 5126, 655–666.
Fischlin, Marc, et al. Robust Multi Property Combiners for Hash Functions Revisited. Vol. 5126, no. PART 2, Springer, 2008, pp. 655–66, doi:10.1007/978-3-540-70583-3_53.
Material in IST: