how to check proof size in VOLE-based ZKP (EMP-ZK)

[xiaozeplus]

thank you all for answering my questions first !

I run your hash and matrix_mul code in Emp-ZK natively in terminal (but not in docker). Every party calculate 4 time: "setup", "sha256", "check", "finalize"

1. who is the prover and who is the verifier?
2. Does the "sha256" time mean prover time?
3. Both parties output the "checlk" time, and which one means the running time for the verifier? (Actually both parties' check time are only 4-5 ns, much smaller than "38.112" provided in your paper, and my CPU is AMD Ryzen 9 7940HX. I run the code in WSL2)
4. how to check the proof size?

[nojansheybani]

Thanks for checking out our work! Let me explain the way VOLE works a bit and then I'll answer your questions in order. VOLE is an interactive scheme, meaning the prover and verifier must be online together for a similar amount of time to achieve proof generation and verification. So the prover time and verifier time are close to the runtime of the whole program that we have in the Dockerfiles. We simply split up the time calculations to provide a more fine-tuned look into how VOLE runs for certain operations to identify any bottlenecks.

1. Party 1 (Alice) is the prover and Party 2 (Bob) is the verifier. We run both on one machine for simplicity
2. "Sha256" is the time it takes for the prover and verifier to interactively compute the sha256 computation within the ZK circuit. Think of this as a back and forth exchange where Alice is trying to prove to Bob that she is computing things correctly
3. Yes, the "check" time is just another small chunk of code that proves that the prover correctly computed sha256 by doing a simple equality check
4. I've made a custom version of the emp-tool repo that should specify the amount of bits sent and received by the prover and verifier. This should be already integrated into the dockerfile, but please let me know if its not. As this is an interactive protocol, we don't have a "proof size", but rather we have "communication", which is the amount of data being transferred between the prover and verifier for the verifier to be convinced of the prover's statement validity