Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 (Tek) 9/26/83; site azure.UUCP Path: utzoo!watmath!clyde!floyd!vax135!cornell!uw-beaver!tektronix!azure!billp From: billp@azure.UUCP (Bill Pfeifer) Newsgroups: net.crypt Subject: Re: One-time pads Message-ID: <2550@azure.UUCP> Date: Wed, 22-Feb-84 13:05:40 EST Article-I.D.: azure.2550 Posted: Wed Feb 22 13:05:40 1984 Date-Received: Fri, 24-Feb-84 00:09:15 EST Organization: Tektronix, Beaverton OR Lines: 46 Gene Spafford writes: > However, suppose you are the person reading the encrypted message. If > you see text which happened to be readable and described a recipe for > Aunt Pat's oatmeal cookies, you probably would ascribe to the > randomness of the encryption. (You might also decide to see if it was a > code of some sort (as opposed to cypher)). On the other hand, if you > saw something like the formula for a new nerve gas, you'd definitely > try to have your chemists put it together and give it a try. Your > chances might not be good that it was actually a formula for nerve gas, > but if it was, you'd have it. Horsepuckey! I suppose Gene does not appreciate the magnitude of the numbers involved! To get a feel for the numbers, consider the famous "Problem of a Printed Line", as described by George Gamow in his book "One Two Three ... Infinity" (Bantam Books, New York). He describes the attempt of continuously printing one line after the other, each line having a different combination of letters, numbers and punctuations, until all possible combinations have been printed. There are 26 letters, 10 numbers and 14 common punctuations, 50 symbols altogether. George Gamow limits the length of the line to 65 characters, that of an average printed line. That is 50^65 or 10^110 combinations! Not impressed yet? Assume that every atom in the entire universe (3*10^74 of them) represents a separate printer, working simultaneously. Assume further that these printers are printing at the rate of atomic vibrations, 10^15 lines per second (that's a quadrillion lines, 16 2/3 trillion pages, or about 5 billion boxes of paper per second EACH), and that they have been printing uninterrupted since the beginning of the universe (3*10^9 years, or 10^17 seconds). By now they would have printed 3*10^106 lines, which is one thirtieth of 1 percent of the total required. The probability of text left unencrypted by a string of zeroes in a truly random bitstream is similar to that of finding the real nerve gas formula in this output. Besides, how much of a formula could you pack into a 65 characters? Remember, each added character multiplies the output volume by 50. Along with the real formula, there will also be 10^xxx phony formulas, some of which will actually yield Aunt Pat's oatmeal cookies. There aren't enough molecules on this planet to put together all formulas that might look like nerve gas, even if you tried. Bill Pfeifer {cbosgd,decvax,harpo,ihnss,ogcvax,pur-ee,ucbvax,zehntel} !tektronix!tekmdp!billp