The guy that wrote A86 http://eji.com says he used two alternate forms of coding some commonly used instructions to encode a signature that allows him to quickly check any published executable to see if it was made with his product. Here is an excerpt from his manual:
A86 takes advantage of situations in which more than one set of opcodes can be generated for the same instruction. (For example, MOV AX,BX can be generated using either an 89 or 8B opcode, by reversing fields in the following effective address byte. Both forms are absolutely identical in functionality and execution speed.) A86 adopts an unusual mix of choices in such situations. This creates a code-generation "footprint" that occupies no space in your program file, but will enable me to tell, and to demonstrate in a court of law, if a non-trivial object file has been produced by A86. The specification for this "footprint" is sufficiently obscure and complicated that it would be impossible to duplicate by accident. I claim exclusive rights to the particular "footprint" I have chosen, and prohibit anyone from duplicating it. This has at least two specific implications. a. Any assembler that duplicates the "footprint" is mine. If it is not identified as mine and issued under these terms, then those who sell or distribute the assembler will be subject to prosecution. b. Any program marked with the "footprint" has been produced by my assembler. It is subject to condition 5 above.
I'm not sure if the same is applicable to PIC code but it would be interesting if it was. The UPS quick cost calculator submission form contains a field: and the cgi that processes the requests won't if that field isn't present and with that value. If you want a good laugh, read that license some time. Well, actually, if you want a good laugh, sign up with UPS. Did you know FEDEX does ground now? --- James Newton (PICList Admin #3) mailto:jamesnewton@piclist.com 1-619-652-0593 PIC/PICList FAQ: http://www.piclist.com or .org -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Harold M Hallikainen Sent: Monday, May 15, 2000 09:01 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [OT] When is a protocol proprietary? On Mon, 15 May 2000 07:38:54 -0400 Chris Eddy writes: > Oh, that is VERY good. Gives me chills. I think I will use that > some time in the > future. > > That is similar to a protection scheme that I heard sometime ago, > probably on the > list.. > > Hide a special key sequence in your menu system. If the competitor > steals your > code, then you can call in your trump card right there in front of > the jury. > Something like this has been used to demonstrate theft of source code. There may indeed be only one way to code a particular algorithm, but it can be shown that it was stolen, not independently derived, by analysis of the white space in the source code (the particular combination of tabs and spaces). Harold FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj.