Yes, as long as the calculation speed is ok, the arithmetic is precise
enough and there is no need to update the 'calculation engine' it is
possibly the best solution, I agree.

Tamas


On 3/26/07, Alan B. Pearce <A.B.Pearce@rl.ac.uk> wrote:
>
> >Most of these solutions are based on public key encryptions. You
> >send a data to the dongle, and the dongle encrypts it or sign it
> >with the private key and sends back the results so the software
> >of yours can check it using the public key.
>
> But you missed my point that I was making in the bit you quoted.
>
> My understanding of Dwaynes situation is this.
>
> He has data that he wishes to manipulate to send to a milling machine to
> make a 1 off PCB.
>
> He manipulates this data using a program on a PC, to generate the
> necessary
> data stream to drive the mill.
>
> By sending the manipulated data from the PC to the mill, the 1 off PCB is
> made, with milled outlines to the tracks.
>
> Now having developed the program, Dwayne wants to distribute it.
>
> My suggestion is to put the calculation engine that converts from the
> original data to the milling machine code into the dongle. There is no
> encryption/decryption involved. The dongle is part of the data path
> between
> the original clear data, and the clear data fed to the mill machine. The
> dongle does all the data manipulation, not the PC program.
>
> By having the dongle do the data manipulation the PC program becomes
> little
> more than a file server/transfer mechanism. The dongle HAS to be present
> for
> the data manipulation to take place, and cannot be bypassed. The PC
> program
> can be copied as many times as anyone likes, but when they disassemble it,
> all they will find is a data path that goes from the input file to the
> dongle. Then from the dongle to the output file. The output file could be
> a
> disk file or it could be straight to the mill.
>
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