Soft input decryption using selective bit flipping combinations strategy

Soft Input decryption (SID) provides an attractive alternative method to decode forward error correction systems using cryptographic algorithms. This paper considers the benefit of using a new strategy called Selective Bit Flipping Combinations Strategy (SBFCS) for soft input decryption. After selecting a group of decoded bits, rather than using all bit flipping combinations in a manner of binary counter, only limited bit flipping combinations are used in a certain order. Taking motivation from the fact that the frequency of occurrence of some bit flipping combinations is higher than that of the other combinations, this strategy flip the bit combinations depending upon the frequency of occurrence i.e., the bit flipping combination having the highest frequency of occurrence is tried first. This achieves a two-fold objective, the bit error rate as well as the error correction speed is improved. To evaluate the efficacy of our heuristics, we conduct computer simulations showing that the SID using SBFCS strategy achieves a performance improvement of about 0.85dB in contrast to conventional communication system with the same coding rate.