We study security amplification for commitment schemes and improve the efficiency of black-box security amplification in the computational setting, where the security holds against PPT active adversaries. We show that ω(log s) black-box calls to a weak bit-commitment scheme with constant security is sufficient to construct a commitment scheme with standard negligible security, where s denotes the security parameter and ω(log s) denotes any super-logarithmic function of s. Furthermore, the resulting scheme is a string commitment scheme that can commit to O(log s)-bit strings. This improves on previous work of Damgård et al. [DKS99] and Halevi and Rabin [HR08], whose transformations require ω(log2 s) black-box calls to commit a single bit. As a byproduct of our analysis, we also improve the efficiency of security amplification for message authentication codes, digital signatures, and pseudorandom functions studied in [DIJK09]. This is from an improvement of the "Chernoff-type Theorems" of dynamic weakly-verifiable puzzles of [DIJK09]. © 2010 International Association for Cryptologic Research.
CITATION STYLE
Chung, K. M., Liu, F. H., Lu, C. J., & Yang, B. Y. (2010). Efficient string-commitment from weak bit-commitment. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 6477 LNCS, pp. 268–282). Springer Verlag. https://doi.org/10.1007/978-3-642-17373-8_16
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