Quantum Circuit Obfuscator

This repository contains an implementation of an obfuscator for quantum circuits. It is the accompanying software artifact for the paper Scalable Verification of Quantum Supremacy based on Circuit Obfuscation Shouvanik Chakrabarti, Chi-Ning Chou, Kai-Min Chung, and Xiaodi Wu.

Overview

The obfuscator takes as input a quantum circuit and increases the number of qubits (by 100) and the number of quantum gates, while producing an 'obfuscated' version of the circuit that is functionally equivalent.

The obfuscator is based on primitives from SQIR, a Small Quantum Intermediate Representation for quantum programs, and the Verified Optimizer for Quantum Circuits (VOQC). The repository is built upon a clone of the SQIR repository. The implementation of the obfuscator is found under the Obfuscator subdirectory.

Compilation

To compile the obfuscator follow these instructions:

Dependencies We recommend using the Ocaml Package Manager opam to install these dependencies. Install opam using the appropriate instructions for your system found here.

OCaml version 4.08.1 (opam switch create 4.08.1)
Coq version 8.10.1 (opam pin add coq 8.10.1)
dune (opam install dune)
menhir (opam install menhir)
OCaml OpenQASM parser (opam install openQASM)

Once the dependencies are installed the obfuscator can be compiled by running make obfuscator in the parent directory. This will produce an executable in Obfuscator/_build/default.

Execution

All commands for running the obfuscator and the benchmarks are to be run in the Obfuscator subdirectory.

Running the obfuscator

In order to use the obfuscator executable run the command

dune exec ./obfuscator.exe <input_file> <output_file> <output_optimized_with_voqc> --root extraction

This returns an obfuscated version of <input_file> in <output_file>, and a version of <output_file> that has been further optimized by VOQC in <output_optimized_with_voqc>. For instance, to run the obfuscator on the benchmark tof_5 and obtain the obfuscated output out.qasm and subsequently optimized circuit optimized_voqc.qasm run the command

dune exec ./obfuscator.exe benchmarks/Arithmetic_and_Toffoli/tof_5.qasm out.qasm optimized_voqc.qasm --root extraction

Running the benchmarks

The benchmark script has the following depencencies.

Python: The benchmarking script requires a working Python 3 distribution that can be obtained here.
Qiskit: The Qiskit package can be installed using any python package manager. If pip is used, simply run pip install numpy.
staq : A clone of the staq repository is included under Obfuscator/benchmarks/staq. To build the executable for a UNIX based system with cmake and a C++ distribution , run the following commands in this directory

cd build
cmake ..
make staq

For other systems follow the installation instructions for staq in the directory Obfuscator/benchmarks/staq.

Given all the dependencies the script Obfuscator/run_benchmark.py will execute all the benchmarks and return CSV formatted results in a file given as input. Running the command

python run_benchmarks.py results.csv

in the Obfuscator directory will return the results in results.csv.

Main components

The main source components of the obfuscator can be found in

Obfuscator/src/obfuscator/ReverseOptimizations.v : contains the main primitives that are combined to form the obfuscator.
Obfuscator/extraction/obfuscator.ml : contains the implementation of the obfuscator executable.
Obfuscator/run_benchmarks.py : contains the code that reproduces the numerical benchmarks found in the paper.