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- Newsgroups: sci.crypt
- Path: sparky!uunet!wupost!cs.utexas.edu!sun-barr!ames!pacbell.com!att-out!cbnewsh!cbnewsh.cb.att.com!wcs
- From: wcs@anchor.ho.att.com (Bill Stewart +1-908-949-0705)
- Subject: Re: Cryptographic copy protection
- Organization: AT&T Bell Labs Random Organization Name Generator
- Date: Fri, 11 Dec 1992 22:05:23 GMT
- Message-ID: <WCS.92Dec11170523@rainier.ATT.COM>
- In-Reply-To: gordon@sneaky.lonestar.org's message of Wed, 9 Dec 1992 05:38:45 GMT
- References: <ByxHyv.5s9.1@cs.cmu.edu> <Byz911.2Lo@sneaky.lonestar.org>
- Sender: news@cbnewsh.cb.att.com (NetNews Administrator)
- Nntp-Posting-Host: rainier.ho.att.com
- Lines: 36
-
- >The point of entry I'm using is the fact that software is interactive.
- >A single use of a piece of software doesn't reveal all of its intricacies
- >(unlike a musical number or a novel). We can therefore hope to force
- >a contact with a host machine H during each unique run of the program,
- >enabling us to insist upon payment.
- [....]
- >The key to success is "cryptographically strong code shuffling" which
- >gives a cryptographic guarantee against disassembly, or more precisely,
-
- In article <Byz911.2Lo@sneaky.lonestar.org> gordon@sneaky.lonestar.org (Gordon Burditt) writes:
-
- [ much discussion on whether anyone would *want* pay-per-view
- software, ways to break implementations, ways that protection
- makes use of the software annoying at best, etc.]
- This description sounds suspiciously like many MS-DOS viruses. I suspect
- that it will be equally popular.
- If the CPU can execute it, it can be disassembled.
-
- ....
- So who says the OS lets the application do self-modifying code? Or
- read its own code? And the debug monitor can disable the checking code
- when the program enters the "contact host & verify" routine, and put it
-
- You can *always* build self-modifying code -- use an interpreter,
- and include the real program as data -- as long as performance
- isn't too critical. If you only need a couple of MIPS of CPU,
- and you've got a RISC or 486/50 or DSP processor, you can write
- the program as p-code or LISP or (shudder) BASIC or Forth,
- or roll your own interpretive system which is more amenable to
- running scrambled. Still don't know if you can solve the problem,
- but at least you've got another tool.
- --
- # Pray for peace; Bill
- # Bill Stewart 908-949-0705 wcs@anchor.att.com AT&T Bell Labs 4M312 Holmdel NJ
- # Nov 12 - Anniversary of Indonesian massacre in East Timor, 1991
- # Indonesia first invaded in 1975, and about 1/3 of the people have been killed.
-