On the Limits of Computational Fuzzy Extractors

Fuller et al. (Asiacrypt 2013) studied on computational fuzzy extractors, and showed, as a negative result, that the existence of a computational “secure sketch” implies the existence of an information-theoretically secure sketch with slightly weaker parameters. In this work, we show a similar negative result such that, under some computational assumption, the existence of a computational fuzzy extractor also implies the existence of an information-theoretic fuzzy extractor with slightly weaker parameters. The assumption is that the generation procedure of the fuzzy extractor can be efficiently invertible. This result implies that to circumvent the limitations of information-theoretic fuzzy extractors, we need to employ computational fuzzy extractors in which the generation procedure cannot be efficiently invertible.