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Cheesecloth witness checker

This tool constructs a witness/trace checking circuit, which checks that a (secret) trace represents a valid execution of a (public) program. The output can be saved in zkInterface format and evaluated using other tools.

To generate the witness checking circuit:

cargo run --release -- examples/memory-3.yaml

The input is a program and trace in the CBOR format produced by MicroRAM. (YAML and JSON representations are also accepted, allowing for human-readable input.) The tool will build and evaluate the circuit and print some output about the status of its various validity assertions and bug checks.

By default, the trace is expected to exhibit a memory safety error. If you only want to check that the trace is valid, use the --validate-only flag:

cargo run --release -- examples/memory-1.yaml --validate-only

To save the circuit in ZKIF format:

cargo run --release --features bellman -- examples/memory-3.yaml --zkif-out zkif

This will produce zkInterface files in the zkif/ directory, which you can later evaluate using mac-n-cheese or a similar tool.

You may need to add CARGO_NET_GIT_FETCH_WITH_CLI=true to cargo commands to clone dependencies.

Output formats

witness-checker can produce circuits in several formats, selected by command-line arguments:

  • --zkif-out DIR: Generate R1CS in zkinterface format in directory DIR/. The constraint system uses the field F128p (integers modulo 2^128 - 159).
  • --sieve-ir-out DIR: Generate an arithmetic circuit in the SIEVE phase 1 IR format ("IR1") in directory DIR/. The circuit uses the field F128p.
  • --sieve-ir-v2-out DIR: Generate an arithmetic circuit in the SIEVE phase 2 IR format ("IR0+") in directory DIR/. The circuit uses the field F128p.
  • --boolean-sieve-ir-out DIR: Generate a boolean circuit in the SIEVE phase 1 IR format ("IR1") in directory DIR/. The circuit uses the field F2 (integers modulo 2).
  • --boolean-sieve-ir-v2-out DIR: Generate a boolean circuit in the SIEVE phase 2 IR format ("IR0+") in directory DIR/. The circuit uses the field F2 (integers modulo 2).

For some output formats, it's possible to select a non-default prime field using the --field-modulus P option.