Haniyeh Rafiee - electrical and computer, Malek-Ashtar University of Technology, Tehran, Iran.
Mohammad Fakhredanesh - Faculty of electrical and computer, Malek ashtar university of technology, Tehran, Iran

In this article, one of the most important methods of steganography on VoIP called echo hiding is improved. This method has advantages in maintaining the statistical and perceptual characteristics of audio signals as well as security against the sensitivity of human audio system (HAS). How-ever, it has lots of errors in detecting coded and hidden mes-sages, which is detectable using existing steganalysis meth-ods. The percentage of extracting messages in these im-proved methods of echo hiding is high, but they lower the security of the method. In this article, a method is presented to improve the method of extracting echo hiding, and en-hance its security through a combined method based on spread spectrum. To improve the extraction, a wrong hypoth-esis is corrected and substituted. To improve security using a pseudo-random key generation algorithm, spread spectrum and echo hiding methods are used randomly. To evaluate the proposed extraction, numerous extraction tests are carried out in the normal state and in the event of attacks. A ste-ganalyser has also been used to assess security improve-ments. The results gained through different experiments on the security of steganography indicate a 3-percent increase in steganalysis errors. The proposed extraction method was modified based on the main method and resulted in more than 10% improvement.

Steganography, echo hiding, spread spectrum, security, Cepstral coefficients, self-symmetric