watermarking on FPGA

I'm going to do a very simple watermarking. I want to embed a signature on unused LUTs. could you please tell me how I can do it?
Thank you very much.

 OR how to embed digital signature in verilog code?

Hamid Kavianathar wrote:

> I'm going to do a very simple watermarking. I want to embed a signature on
> unused LUTs. could you please tell me how I can do it? Thank you very
> much.
The simplest way is just to have a register that can be read out in some 
manner that has a permanent value.  This is a lot more like a serial number 
than a "watermark".  If you mean a thing that affects the logic operations 
in some subtle way, I really can't imagine how to do that.  Some FPGAs do 
have laser-programmed unique serial numbers built into the chip.

Jon

On 2/3/2016 5:36 AM, Hamid Kavianathar wrote:
> I'm going to do a very simple watermarking. I want to embed a signature on unused LUTs. could you please tell me how I can do it?
> Thank you very much.

Disregarding any way to actually read out the signature, it seems like a 
no-brainer to simply write your signature to a multi bit register loaded 
at startup.  Just make sure the register is not synthesized away due to 
no output use.

There are at least a few requirements that are unknown:
1. Shall the watermark be readable from the FPGA bit file?  In other 
words, an FPGA is not even needed for the IP to hold the watermark.
2. Shall the watermark be readable via some mechanism?  If not, I can't 
see any reason for it.
3. I believe FPGA vendors are starting to provide security features. 
Will one of those vendor products meet your needs for a lot less effort?

JJS

On 03/02/16 13:36, Hamid Kavianathar wrote:
> I'm going to do a very simple watermarking. I want to embed a signature on unused LUTs. could you please tell me how I can do it?
> Thank you very much.

What *problem* are you trying to solve with "watermarking"?
Only after defining that can you begin to think whether
watermarking is a sufficient solution.

"If you think cryptography will solve your problem,
you don't understand cryptography and
you don't understand your problem".