Generalized least significant bit matching (G-LSB-M) steganography scheme is a 1 embedding method which minimizes the number of modifications per pixel to improve the embedding efficiency.The sum and difference covering set (SDCS) used for embedding can only be obtained through exhaustive search

which is hard to implement when the number of message bits increases.To solve this problem

we provide a novel steganography method based on the extended SDCS (ESDCS).The ESDCS is constructed by removing redundant elements from the so-called basic SDCS without exhaustive search

which implies that longer message segments could be used in the embedding process.The proposed method reduces the expect number of modifications and thus improves the embedding efficiency as well as the security of steganography.