PutBarrelRightShifterGate Problem about aby

[Oleksandr-Tkachenko]

Thanks for pointing this out. The way you are using ABY is correct. The problem was a bug in this function. It should work fine now. Please try out the new version and if you will face any problems, just let me know.

[Oleksandr-Tkachenko]

Hi,

the Barrel Shifter gate works indeed as expected. Since ABY internally uses big-endian representation (C/C++ uses little-endian), PutRightBarrelShifter(<110>, <1>) = 110 << 1 = 0x6E << 1 = 220 = 0xDC. Furthermore, shifting the value 110 you would get neither 11 nor 1100 because these are decimal numbers and values are shifted bit-wise. For this purpose, I would suggest using the more intuitive hexadecimal representation, i.e., 0x6E for the decimal 110 and 0x06 for the binary 110. Another possibility is also to use the binary representation in C++17 as 0b0000'0110 which, however, has to
be first enabled in the compiler.

P.S.: to prevent confusion because of the changing endianness, I will switch left and right shift functions, so the shifting logic will be the same as in C.

Best,
Alex

[akappy7]

Thank you for the response. Closing the issue.

[akappy7]

I believe line 3144 of src/abycore/circuit/booleancircuits.cpp should be:

vector<uint32_t> res = PutBarrelLeftShifterGate(wires, n);

instead of:

vector<uint32_t> res = PutBarrelRightShifterGate(wires, n);

Also, would it be possible to give an example of a PutBarrelRightShifterGate with the new implementation? (Maybe using the same values of 110 and 1). I expect 55 to be the result but that is not the result I am seeing. I am getting "3959422976".