Information capacity of quantization steganography in the presence of active attack

An active warden can significantly reduce the steganographic information capacity by slightly modifying some contents of suspected media. When using QIM-based embedding methods, the steganographic capacity in the presence of active attack can be obtained with a secure transform, an identical suitable quantization step and a corresponding length of embedded bits. It is shown that the maximum attainable payload is determined by the size of cover media and the ratio between distortion levels caused by the data-hider and the active warden respectively