Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!columbia!caip!meccts!mecc!sewilco From: sewilco@mecc.UUCP (Scot E. Wilcoxon) Newsgroups: net.crypt Subject: Re: randomly adding bits/bytes (compressing text before encryption) Message-ID: <557@mecc.UUCP> Date: Thu, 21-Aug-86 16:04:39 EDT Article-I.D.: mecc.557 Posted: Thu Aug 21 16:04:39 1986 Date-Received: Fri, 22-Aug-86 09:25:23 EDT References: <8608042018.AA04376@ucbjade.Berkeley.Edu> <7024@utzoo.UUCP> <806@petsd.UUCP> <553@mecc.UUCP> <1144@ttrdc.UUCP> Reply-To: sewilco@mecc.UUCP (Scot E. Wilcoxon) Organization: MN Ed Comp Corp, St Paul, MN Lines: 90 Summary: Confirmation by example that compress output starts with plaintext. In article <1144@ttrdc.UUCP>, levy@ttrdc.UUCP (Daniel R. Levy) writes: >In article <553@mecc.UUCP>, sewilco@mecc.UUCP (Scot E. Wilcoxon) writes: >>... >>The compress program's output is more compressed as it goes along, so that >>the beginning is practically in plaintext. > >It IS?? Here is an od -c of the first part of the replied-to article, put >through compress: [example deleted/moved to end of article] It is. The characters have been expanded from 8 to 9 bits. The ninth bit is on the 'left' of the other eight, and is shifted on the right of the following byte. The ninth bit is used as compression begins. > >Now if someone can show how this is "plaintext" I'd be mildly interested... Here's an expansion of the first two lines of the example, where "^" points at the bits above, "." and the character point at bits below, and "---" are just spacing. (Or just read the translation along left margin) >0000000 037 235 220 F 344 274 i 003 202 \r 235 : x 302 204 030 (blocked, 16 bits) 0000000 037 235 220 01000110 F ^^^^^^^^---F 11100100 r ^^^^^^^---r. 10111100 o ^^^^^^---o.. 01101001 m ^^^^^---m... 00000011 ^^^^--- .... 10000010 l ^^^---l..... 00001101 t ^^---t...... 10011101 u ^---u....... 00111010 01111010 x ^^^^^^^^---x 11000010 a ^^^^^^^---a. 10000100 ! ^^^^^^---!.. 00011000 c ^^^^^---c... >0000020 S ' L 031 031 ! 322 240 q 003 207 F 210 6 e 306 0000020 01010011 u ^^^^---u.... 00100111 a ^^^---a..... 01001100 ------- e ^^---e...... 00011001 2 ^---2....... 00011001 00100001 ! ^^^^^^^^---! 11010010 i ^^^^^^^---i. 10100000 h ^^^^^^---h.. 01110001 n ^^^^^---n... 00000011 p ^^^^---p.... 10000111 4 ^^^---4..... 01000110 ! ^^---!...... 10001000 m ^---m....... 00110110 01100101 e ^^^^^^^^---e 11000110 c ^^^^^^^---c Since I did that by hand, that's quite enough. Apparently the article got to levy@ttrdc through the path mecc!ihnp4!cuae2!ltuxa!ttrdc. Ttrdc is apparently not running a version of news which puts the local site name in saved messages. -- Scot E. Wilcoxon Minn Ed Comp Corp {quest,dicome,meccts}!mecc!sewilco 45 03 N 93 08 W (612)481-3507 {{caip!meccts},ihnp4,philabs}!mecc!sewilco Laws are society's common sense, recorded for the stupid. The alert question everything anyway.