Steganography is the art and science of hiding information so that nobody but the sender and receiver knows it is there. It differs from cryptography, which makes no attempt to hide a transmission but makes it impossible to read by an eavesdropper.
One seemingly ideal way to hide messages is to mix them into the digital file that makes up an electronic image. These provide good hiding places because images tend to be noisy and complex, providing the perfect background against which a message can blend in.
But Yun Shi at the New Jersey Institute of Technology in Newark, US, has worked out a way of spotting such messages. He does it by analysing the special features that noise may have in an image, and then looking for elements that do not match those features.
For example, regions of texture within an image are often noisy. But they are not entirely random, and have specific characteristics that differ from any image or text hidden in the data describing that region.
Shi has developed software that uses this idea to look for hidden messages in images. He says it significantly improves on current abilities to spot steganographic messages.
Read the full secret message finderpatent application
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