A Weighted Bit Flipping Decoder for QC-MDPC-based Cryptosystems

A new “Weighted Bit-flipping” (WBF) iterative decoder is presented and analyzed with respect to its Decoding Failure Rate (DFR). We show that the DFR is indeed lower than that of the BGF decoder as suggested by the BIKE third round submission to the NIST PQC standardization process. The WBF decoder requires more iterations to complete than BGF, but by creating a hybrid decoder we show that a lower DFR compared to that of the BGF decoder can still be achieved while keeping the computational tradeoff to a minimum.