> Has this been done before? (Try not to throw plates at me if it has)

Yes, manu USB dongle do that.

> I've heard about the "code protect" feature of PIC chips. Does this
> feature prevent the program code from being read from the chip? Is it
> 100% secure?

Nope, even Microchip said there is no 100% protection. If you do a little
search on piclist archives you will find links to pages reverse engineering
chips, like PIC. They have to use advanced technology, so people in garage
unlikely to break your code but it can be done. Depends on how valuable your
stuff is...

Tamas



On Wed, Jun 25, 2008 at 6:04 PM, Tom=E1s =D3 h=C9ilidhe <toe@lavabit.com> w=
rote:

>
> Let's say I came up with a very special algorithm, one that would be
> very valuable to sell.
>
> If I distribute it as a binary executable file for something like
> Windows or Mac, then of course people can just look at the machine code
> to figure out what it's doing.
>
> I've been looking into using a microcontroller to keep an algorithm
> private. Let's say I have an algorithm as follows:
>    It takes a 128-Bit number as input and gives a 128-Bit number as outpu=
t.
>
> Now here's what I have in mind:
>    I get my hands on a microcontroller that has either built-in USB or
> built-in Ethernet. I compile my algorithm for the microcontroller in
> question. I produce a device about the size of a matchbox and sell it,
> and the consumer plugs this device into their PC, perhaps into a USB
> port. The microcontroller will take input from the PC, run the algorithm
> and then give output to the PC.
>
> Has this been done before? (Try not to throw plates at me if it has)
>
> I've heard about the "code protect" feature of PIC chips. Does this
> feature prevent the program code from being read from the chip? Is it
> 100% secure?
>
> Lastly, how would you suggest I go about this: USB or Ethernet. Ethernet
> would be handy in that I could set it up as a webserver that takes input
> and then gives the output on a webpage. Another good thing about this is
> that it would be platform independent and would work on anything that
> has a web browser.
>
> USB would be attractive because it's what people are "used to" and it
> seems USB ports are more ubiquitous than Ethernet ports. Also I do away
> with a batter because I can take power from the USB port. How good is
> USB though when it comes to cross-platform development?
>
> --
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