crypt-dev - Re: alternative approach

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Date: Mon, 13 Jun 2011 19:55:27 -0300
From: Yuri Gonzaga <yuriggc@...il.com>
To: crypt-dev@...ts.openwall.com
Subject: Re: alternative approach

>
> 2. All four LUT counts are a lot higher than those you had reported for
> bflike.  Are they for something else?


Wasting some time to answer this question, I figured out that the first
result (lower LUT count) was to the wrong version of verilog code.
So, the correct result is that with higher LUT count.

1. The smallest LUT count is for the original pcadd(), contrary to what
> you had said.


Yes. I ran again and the results are still the same. So, please, forget
previous ones.

Can you perhaps share the corresponding four pieces of code as well?


`define NROUNDS_DIVIDED_BY_2 1
`define PCADD(a, b, mask) (((a) ^ (b)) + (((a) & (b) & (mask)) << 1))
//`define PCADD(a, b, mask) a^b^mask
//`define PCADD(a, b, mask) a^b
//`define PCADD(a, b, mask) a+b

(...)

for(i = 0; i < `NROUNDS_DIVIDED_BY_2; i=i+1) begin
r = r ^ `PCADD(s[l[3:0]],s[16+(l>>4)], 8'h55);
l = l ^ `PCADD(s[r[3:0]],s[16+(r>>4)], 8'haa);
end


Regards,

Yuri

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