A Note on a Fatal Error of Optimized LFC Private Information Retrieval Scheme and Its Corrected Results

A number of lightweight PIR (Private Information Retrieval) schemes have been proposed in recent years. In JWIS2006, Kwon et al. proposed a new scheme (optimized LFCPIR, or OLFCPIR), which aimed at reducing the communication cost of Lipmaa's O(log2 n) PIR(LFCPIR) to O(log n). However in this paper, we point out a fatal error of overflow contained in OLFCPIR and show how the error can be corrected. Finally, we compare with LFCPIR to show that the communication cost of our corrected OLFCPIR is asymptotically the same as the previous LFCPIR.

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