Improving the Embedding Efficiency of Wet Paper Codes by Paper Folding

Wet paper codes are used to design steganographic schemes, in which the sender can embed messages into a cover with arbitrarily selected changeable bits that are not shared by the recipient. In this letter, we propose a novel approach to wet paper codes by folding the cover into several layers and applying basic wet paper coding methods with low computational complexity to each layer. This method uses the changes introduced in the first layer to embed messages into every layer and therefore achieves high embedding efficiency (average number of bits embedded by per change).