From: dr261@cleveland.Freenet.Edu (Tobin T Fricke)
Date: Tue, 5 Sep 95 11:22:45 PDT
To: cypherpunks@toad.com
Subject: [trei@process.com:       Re: VCRPLUS Huffman code]
Message-ID: <199509051806.OAA03038@kanga.INS.CWRU.Edu>
MIME-Version: 1.0
Content-Type: text/plain


    ================= Begin forwarded message =================

    From: trei@process.com (Peter Trei)
    To: miniters@citadel.edu, cypherpunks@toad.com
    Subject:       Re: VCRPLUS Huffman code
    Date: Tue, 05 Sep

    
    
    > Has anyone worked out the VCRPLUS code?
    
    It was partially broken a few years ago, and the results published in
    Cryptologia. I have a xerox in a carton somewhere. 
    
    The break was for codes up to 4or 5 digits long, if I recall - this covers
    most of the major timeslots on the main stations. Longer codes
    cover odd timeslots on less popular stations.
    
    Code which implemented this partial crack was published on the net,
    and the VCR+ people got very upset about it - apparently they make
    money selling the codes to TV Guide and newspapers. It's protected
    as a trade secret, not a patent.
    
    It used a combination of lookup tables and Huffman codes, and
    included a certain amount of obfuscation to resist cracking.
    
    Peter
    
    
    Peter Trei
    Senior Software Engineer
    Purveyor Development Team                                
    Process Software Corporation
    http://www.process.com
    trei@process.com
    
    

--
Tobin Fricke (aka LightRay)       The Digital Forest BBS (714)586-6142
dr261@kanga.ins.cwru.edu          KE6WHF Amateur Radio, 1:103/925 fido