Regression or incorrect usage?

[richs27]

Hi Marcus,

I've spent some time recently working with a number of 5 input, 2 output Sboxes and have noted what are in this use case, significant differences in gate counts between two versions of sboxgates.

Using a version I git checked out on 4th July 2019, with the following sbox.txt:
3 1 0 2 2 3 3 0 1 3 2 1 0 0 1 2 3 1 0 3 3 2 0 2 0 0 1 2 2 1 3 1
and using the command:
../sboxgates -l -i 1000 -b sbox.txt
I get 193 2-008-0000-01* results.

If I run the same command with the latest version, the lowest gate count I can acheive is 2-010.

Other sbox descriptions, 5in 2out, show one gate lower results, again with the older version.

Is this just a reflection of heuristic differences between the versions or am I not using the tool optimally? In the first example, nothing I tried with the latest version would generate any two output result below gates.

Also, is there any "rule of thumb" around the number of iterations one should use?

Thanks.

[dansarie]

Thanks for reporting this! It could very well be a bug, I'll investigate and see what I find. Unfortunately, I'm a bit busy with other work at the moment, so it may take some time.

Also, is there any "rule of thumb" around the number of iterations one should use?

A higher number of iterations makes it likelier to find smaller representations. However, the computation time can increase significantly - especially for large S-boxes. In short, pick a number of iterations that give you a running time you are ok with.

[richs27]

Thanks. Also, the command I'm using above is missing an "mpirun" at the beginning.

[richs27]

I 've just checked through your commit history and found that the "-n" option was added later than the July 4 2019 date most of the files in the early checkout, are dated and it's available in this version.

Is there a way of finding out the version I have?

[dansarie]

Other than looking at the git history of your local repo or comparing files manually to previous commits, I don't think there's a way to tell which version you have.