Current believed-optimum CyberSitter-decoder (43 chars): perl -lne 's/./$&^"\x94"/ge;map print,/[ ,-9A-}]{5,}/g' cywin0.opt From: Jamie McCarthySubject: XOR ( 0x94 ) Date: Apr 26, 1997 To: fight-censorship@vorlon.mit.edu peacefire-talk@vorlon.mit.edu Cc: postmaster@solidoak.com Regarding the CyberSitter "encrypted" filter file, Bennett Haselton wrote: >The filter file codebreaker just XOR's every character with 0x94 and >extracts all strings that are more than 4 printable characters long. You've got to be kidding me. Just amazing. And here I thought we were living in the 1990s. XORing with a fixed value is the kind of "encryption" I used in high school, and even then I knew it wouldn't keep out a determined 9th grader. Here's a program which, according to Brian Milburn, "illegally modifies and decodes data and source code protected by U.S. and International intellectual property laws." Invoke from a unix command line: perl -0777ne '$_^="\224"x length;@a=grep/.{5}/,split/[^\w,.[\]{}]+/; $"="\n";print"@a"' cywin0.opt > cywin0.txt Note that: (a) none of Solid Oak's source code is involved (obviously) and (b) the data in question is available with no notices about intellectual property at ftp://acorn.solidoak.com//Anonymous/cywin0.opt . The README file in that directory appears to have nothing to do with this file, and there is no notice in the "230" header returned by the FTP server. The program itself is 70 bytes long (85 if you count the unix trimmings) and took me ten minutes to write. Will Solid Oak now send me a demand letter asking me to stop distributing those 70 bytes? Stay tuned. The program is based _solely_ on Mr. Haselton's description, quoted above, which is 22 words long. Will Solid Oak now threaten to sue him (again) for uttering those 22 words? Stay tuned. Posted to fight-censorship and peacefire-talk. Cc'd to postmaster@solidoak.com. Bcc'd to a friend of mine at PGP, Inc., for his amusement. -- Jamie McCarthy http://www.absence.prismatix.com/jamie/ jamie@nizkor.org Director of Operations, The Nizkor Project http://www.nizkor.org/ Date: Sat, 26 Apr 1997 22:38:11 -0400 Message-Id: <9704270238.AA08935@frumious-bandersnatch.MIT.EDU> From: Seth Finkelstein To: jamie@voyager.net Subject: cybersitter decoder contest > I still prefer .{5} because you lose some info otherwise. Even .{5} > loses some info -- check out what it does with "don't,buy,cybersitter" -- > I think the apostrophe-t gets lost. Which reminds me, apostrophe should > be in the character class there (or rather its negation). I know it > hurts to use one _more_ character but it seems more correct :-) The apostrophe is even more of a headache, because it'll mess up the csh quoting. We can cut through this with rewriting the range of the regexp. > Is there a reason there's a terminal semicolon before the last '? It's > unnecessary, isn't it? You're right. How's this (re-arranging the $_ position): perl -lne '$,=$/,print grep/.{6}/,split/[^ ,-9A-}]+/,$_^="\224" x length' ================ Seth Finkelstein sethf@mit.edu Received: from kaukau.mcs.vuw.ac.nz (kaukau.mcs.vuw.ac.nz [130.195.5.20]) by vixa.voyager.net (8.8.5/CICNet) with ESMTP id BAA06927 for ; Wed, 30 Apr 1997 01:19:29 -0400 (EDT) Received: from bats.mcs.vuw.ac.nz (bats.mcs.vuw.ac.nz [130.195.5.13]) by kaukau.mcs.vuw.ac.nz (8.8.5/8.8.5) with ESMTP id RAA28867; Wed, 30 Apr 1997 17:22:37 +1200 (NZST) Received: (from phil@localhost) by bats.mcs.vuw.ac.nz (8.8.5/8.7.3) id RAA02029; Wed, 30 Apr 1997 17:22:37 +1200 (NZST) Sender: phil@bats.mcs.vuw.ac.nz To: jamie@voyager.net (Jamie McCarthy) Subject: Re: Decoding CyberSitter in 1 line - but how long a line? References: Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII From: Phil Abercrombie Date: 30 Apr 1997 17:22:36 +1200 In-Reply-To: jamie@voyager.net's message of Tue, 29 Apr 1997 23:50:04 -0400 Message-ID: <6wyba1qe3n.fsf@bats.mcs.vuw.ac.nz> Lines: 11 X-Mailer: Gnus v5.4.25/Emacs 19.34 Depends a little what YOU mean by "printable". > perl -lne '$,=$/;print grep/.{5}/,split/[^ ,-9A-}]+/,$_^="\224"x length' cywin0.opt Here's my 1 liner $ perl -lne 's/./$&^"\x94"/ge;map print,/[ -~]{5,}/g' cywin0.opt I don't understand the politics behind all this, I just write code. -phil
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