Xref: utzoo comp.compression:78 sci.crypt:4377
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!uunet!ns-mx!pyrite.cs.uiowa.edu
From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: comp.compression,sci.crypt
Subject: Re: Security of PKZIP's encryption
Message-ID: <5062@ns-mx.uiowa.edu>
Date: 26 Mar 91 20:26:42 GMT
Article-I.D.: ns-mx.5062
Sender: news@ns-mx.uiowa.edu
Followup-To: comp.compression
Lines: 21

From article <1991Mar26.150049.20882@athena.cs.uga.edu>,
by is@athena.cs.uga.edu (Bob Stearns):

> While I commonly recommend PKZIP (tm) for saving space on a hard disk,
> I have been asked how strong its encryption (-spassword) option is.

As I pointed out in my CACM article on splay-tree based compression, the
initial state of just about any adaptive compression algorithm can be
used as a key for encryption/decryption of the compressed stream.  This
applies to my splay-tree based algorithm as well as applying to LZW,
adaptive arithmetic codes and various adaptive Huffman codes.  I have
enquired periodically about the security of the -p password option on my
splay-tree based compressor, but other than one E-mail response from
Moscow (of all places), I've heard nothing.  The response from Moscow
was that they were investigating this issue but had no results yet.

So, Bob Stearns, pleasy summarize what you learn to the net, and
netlanders, please send E-mail to Bob if you know anything about this.

					Doug Jones
					jones@cs.uiowa.edu