Reversible data hiding for VQ indices using XOR operator and SOC codes

Reversible data hiding method can protect secret data by embedding secret data into cover media, e.g., images, videos, audio files and compression codes. In 2014, Qin et al. proposed an index parity matching method to embed secret data into compression codes, i.e., vector quantization (VQ) indices. In the index parity matching method, the difference between the current embedding VQ index and its neighboring index is calculated. The original VQ index is replaced by the difference, its ID number and one secret bit. However, recoding the signal value of the difference causes more compression codes. In order to solve this problem, we skillfully use the exclusive-or (XOR) operator to calculate the difference between the two neighboring indices. The XOR operator does not generate any negative number, thus the proposed method does not record the signal value. Experimental results showed that the proposed method can embed more secret data than the previous methods. In addition, under the same hiding capacity, the bitrate of the proposed method is lower than that of the previous methods.