This technique has been publicly known for well over a decade. See: http://www.amazon.com/Information-Techniques-Steganography-Digital-Watermarking/dp/158053035

This technique has been publicly known for well over a decade. See: http://www.amazon.com/Information-Techniques-Steganography-Digital-Watermarking/dp/1580530354 http://www.amazon.com/Information-Techniques-Steganography-D... It's been a long time since I read it, but if I recall correctly, the UK government has been encoding the identity of the receiver of highly sensible information in this fashion for a long time. Probably it is SOP by now in most environments where truly important secrets are exchanged.