Abstract: The core of steganographic research is capacity and security of hiding information. According to Cachin'definition of security and properties of binary image block of host image, batch steganographic model of binary images was presented. Batch steganographic capacity of binary images was summarized, when satisfying static markov chain and mutually independent of embedding in covers. Security of the model was proved under certainly condition. The experimental results and analysis show that the model satisfies steganographic requirement for security. The research results are helpful for theory and application.

Key words: Information hiding,Batch steganography, Binary image, Security