数字隐写中的素数基广义游动编码

摘要

隐写编码可以提高数据嵌入效率和隐写安全性.该文将原有的二进制游动隐写编码法推广为广义素数基游动编码.秘密信息首先表示为某一素数进制下的位序列,每一秘密数据位又用连续多个载体数据来承载.在此机制下,隐写时每修改一个载体数据值就可以隐藏多个秘密数据位,因此大大减少了对载体数据的修改量,即提高了嵌入效率.原有的二进制游动编码实际上是广义游动编码方法在素数基等于2时的特例.理论分析表明,在素数基取为3时可以获得最好的编码性能.%Steganographic coding such as the running coding described in a previous work can be used to improve embedding efficiency,thus enhance steganographic security.In this paper,we modify the original running coding method and propose a generalized scheme with a prime base.With the generalized approach,each secret digit in a notational system using a prime base is represented by a series of cover values.Alteration to one cover value is usedto embed several secret digits so that distortion is significantly reduced.The previous running coding is in effect a special case of the generalized scheme with a prime base P=2,i.e.,the binary system.Theoretical analysis indicates that the generalized running coding with P=3 provides the best performance.