A SVM based text steganalysis algorithm for spacing coding

Group distance coding is suitable for secret communication covered by printed documents. However there is no effective method against it. The study found that the hiding method will make group distances of text lines coverage on specified values, and make variances of group distances among N-Window text lines become small. Inspired by the discovery, the research brings out a Support Vector Machine (SVM) based steganalysis algorithm. To avoid the disturbance of large difference among words length from same line, the research only reserves samples whose occurrence-frequencies are ±10dB of the maximum frequency. The results show that the correct rate of the SVM classifier is higher than 90%.