🚀 go-pugleaf

In article <164@teak.athertn.Atherton.COM>, ericb@athertn.Atherton.COM (Eric Black) writes:
> In article <556@cresswell.quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) writes:
> >It *is* in the interest of the hardware vendor to prevent piracy
> >of *their* software.  So you are likely to see hardware serial numbers
> >on machines whose manufacturers have a range of unbundled software.

> Now, given that assumption (which is just that), why would the hardware
> manufacturer care if you tried to run the same software on another of
> his machines?

He wouldn't.  But consider the PC market.  IBM would *love* it if
software bought to run on one of their machines wouldn't run on a
clone!

> Unfortunately, short of providing decryption built-in to the CPU chip in
> the instruction fetch path, the fact is that at some point in the program's
> runtime existence, there MUST be a "cleartext" version of the code.

This is just plain wrong.  Or rather, it depends on what you mean by
"the code".  There need never be a cleartext version of the hardware
serial number.

> protection schemes, at some point in the program's execution it makes a
> GO/NO-GO decision as to whether the execution is authorized.  Both can be
> defeated by a sufficiently-motivated pirate.

There need not be a single point.  For example, the program could contain
several copies of the test, and every n*10 seconds for n some small
random integer, execute a random copy of the test, and stop if it fails.
The test need not be explicit.  For example, a critical data structure
could be decrypted using the serial number as encryption key, and the
program could encrypt it at run time.  (Yes, de- and en- are the right
way around.)  {The symbol table and error message table are the obvious
choice, because one might want to supply language-specific versions
anyway.}

A sufficiently motivated pirate could break into our offices,
or monitor the electrical signals from our keyboards, or do lots of
other things.  Is that a reason not to stop the pirates we CAN stop?