S. Ma, X. F. Zhao, Q. X. Guan, Z. J. Xu, Y. Ma
Many contemporary steganographic schemes aim to embed fixed-length secret message in the cover while minimizing the stego distortion. However, in some cases, the secret message sender requires to embed a variable-length secret payload within his expected stego security. This kind of problem is named as secure payload estimation (SPE). In this paper, we propose a practical SPE approach for individual cover. The stego security metric we adopt here is the detection error rate of steganalyzer (P_E). Our method is based on a priori knowledge functions, which are two kinds of functions to be determined before the estimation. The rst function is the relation function of detection error rate and stego distortion (P_E-D function). The second function reflects the relationship between stego distortion and payload rate (D-a) of the chosen cover. The P_E -D is the general knowledge, which is calculated from image library. On the other hand, D-a is for specic cover, which is needed to be determined on site. The estimating procedure is as follows: firstly, the sender solves the distortion D under his expected P_E via P_E-D, and then calculates the corresponding secure payload via D-a of the cover. For on-site operations, the most time-consuming part is calculating D-a function for cover image, which costs 1 time of STC coding. Besides this, the rest on-site operations are solving single-variable formulas, which can be easily tackled.Our approach is an ecient and practical solution for SPE problem.
Cite the paper as:
 S. Ma, X. F. Zhao, Q. X. Guan, Z. J. Xu, Y. Ma. A priori knowledge based secure payload estimation. Multimedia Tools and Applications, First online: July 4, 2017, DOI: s11042-017-4955-8, Springer