At 12:19 AM 4/12/96 -0400, JonWienke@aol.com wrote:

I just added a feature to my entropy graphing program that estimates the number of bits of entropy in the file,

Hey, that's just what I need. I have these two 8-million byte files. One is a recording made by a geiger counter, every bit is uncorrelated with anything else in the universe and each bit is equally likely to be a one or a zero. The second file is an IDEA encryption of all the four-byte numbers from one to two-million. Here's my problem. I can't remember which file is which, and I've forgotten sixty-four bits of the key I used to produce the encrypted file. That's where your technique come in. The first file has sixty-four million bits of entropy. The second file has only sixty-four bits of entropy, total (the missing key bits). Surely, your technique can tell me which file is which. Estimating entropy can be difficult, and I don't expect perfection. But any measuring technique that is not a complete HOAX must be able to clearly find a difference of six orders of magnitude. If you tried to give me a ruler that couldn't detect the difference between a millimeter and a kilometer, I might think you misunderstood something about the concept of distance. If encouraged me to use a clock that could not measure the difference between a minute and a year, many would conclude that you were not an expert in chronology. So, if your technique is worth anything at all, it should be able to accomplish this easy task. PS. I think it is your patriotic duty to report this technique to the Federal government. They frequently need to distinguish between ciphertext and just plain random digits. A breakthrough like this would have a major impact on national security. They might be willing to remove ITAR restrictions from cryptography, out of gratitude to the cypherpunks.