Question about Comparison Implementation & Malicious Security

[BlackFH]

Hi @ladnir, I'm encountering difficulties while implementing a comparison and would appreciate your guidance.
My proposed approach for comparing two secret-shared si64Matrix a and b:
1.Compute c = a - b
2.Apply toBinaryMatrix conversion to c
3.Extract MSB
4.Perform bitInjection
Could you confirm if this workflow is fundamentally correct for implementing a secure comparison? When executing toBinaryMatrix, I encounter the error:

party 1 next 1213 mode=server?:1 name 12
party 1 prev 1212 mode=server?:0 name 01
party 1 start
network receive error01._autoName_0 ): End of file
 at  /home/ubuntu-14900k/Desktop/aby3/thirdparty/libOTe/cryptoTools/cryptoTools/Network/Channel.cpp:818
~~~~~~~~~~~~~~~~ Runtime not empty!!! ~~~~~~~~~~~~~~~~
End of file

My code is:

   IOService ios;
   
   Sh3Encryptor enc;
   Sh3Evaluator eval;
   Sh3Runtime runtime;
   Sh3Converter convt;

   setup(partyIdx, ios, enc, eval, runtime);
   u64 row = 1;
   u64 col = 1;
   eMatrix<i64> plainMatrix(row, col);
   for (u64 i = 0; i < row; ++i)
   	for (u64 j = 0; j < col; ++j)
   		plainMatrix(i, j) = 5;
   si64Matrix sharedMatrixA(row, col);


   if (partyIdx == 0)
   	enc.localIntMatrix(runtime, plainMatrix, sharedMatrixA).get();
   else
   	enc.remoteIntMatrix(runtime, sharedMatrixA).get();

   sbMatrix sharedMatrixB(sharedMatrixA.rows(), sharedMatrixA.cols() * 64);
   Sh3Task mulTask = convt.toBinaryMatrix(runtime, sharedMatrixA, sharedMatrixB);
   mulTask.get();
   return 0;

What could be causing this runtime error? Are there specific preconditions for using toBinaryMatrix that I might have missed?

BTW, does ABY3 natively support malicious security settings? If not, should I implement additional checks?

Thank you for your time and expertise!

[ladnir]

looks correct, this must be a bug in the runtime. Im a bit busy at the moment and can't debug this issue. If you can check in a month I can help.

Another option is to use MP-SPDZ. They have many protocols and is better supported.

Malicious is non-trivial to add. I would suggest MP-SPDZ.