On Mon, 28 Feb 1994, Norman Hardy wrote:
Has anyone done statistical studies of low bits of pixels or sound samples? I suspect that they are often far from random. A flat 50% distribution in the low bits might standout like a sore thumb. I can imagine the the low bit can be distributed dependently on such things as the next to low bits or 60 cycle power at the recorder. Some AD converters are known to produce 60% ones or some such. Like mechanical typewriters, AD systems probably have there own idiosyncrasies. Given a flat stream of cipher data, there are techniques to reversably introduce such variations to mimic the biases of real AD converters without much data expansion.
It is my wild guess and conjecture that with such statistical variation built in there would be no effective statistical test for a given file containing hidden messages.
Yes, pure white noise would be anamalous. I have suggested that one use a Mimic function with a "garbage grammar". Implemented correctly, it should withstand statistical analysis. What is an AD converter? And what are the techniques you speak of that mimic those AD converters? Sergey