#air #stark #zero-knowledge #zkp #winterfell

air-codegen-winter

Winterfell code generator for the AirScript language

1 unstable release

Uses new Rust 2021

0.1.0 Nov 10, 2022

#701 in Cryptography

34 downloads per month
Used in air-script

MIT license

77KB
1.5K SLoC

Winterfell Code Generator

This crate contains a code generator targeting the Winterfell prover Rust library.

The purpose of this code generator is to convert a provided AirIR representation of an AIR into a custom Rust struct that implements Winterfell's Air trait. The generated code can be used instead of writing a custom Winterfell Air implementation directly in Rust.

Generating the Winterfell Rust Code

Generate Rust code from an AirIR (AirScript's intermediate representation) by instantiating a new CodeGenerator with an AirScript AST (the output of the AirScript parser) and then calling generate. The generate method will return the Rust code implementation as a String.

Instantiating the CodeGenerator will add the required Winterfell imports, create a custom struct using the name defined for the AIR, then implement the Winterfell Air trait for the custom struct.

Example usage:

// parse the source string to a Result containing the AST or an Error
let ast = parse(source.as_str()).expect("Parsing failed");

// process the AST to get a Result containing the AirIR or an Error
let ir = AirIR::from_source(&ast).expect("AIR is invalid");

// generate Rust code targeting the Winterfell prover
let rust_code = CodeGenerator::new(&ir);

Generated Winterfell Rust Code

The following code is generated for the Winterfell Air trait implementation:

  • declaration and implementation of a PublicInputs struct.
  • custom struct declaration and implementation, using the defined name of the AIR from the original AirScript file
  • implementation of Winterfell Air trait:
    • constraint-related declarations as part of the AirContext creation in the new method:
      • the number of boundary constraints for the main trace
      • the number of boundary constraints for the auxiliary trace
      • the order and degrees of the transition constraints for the main trace
      • the order and degrees of the transition constraints for the auxiliary trace
    • getters for:
      • periodic column values (get_periodic_column_values)
      • main trace boundary constraints (get_assertions)
      • auxiliary trace boundary constraints (get_aux_assertions)
    • transition constraint evaluation code for:
      • main trace transition constraints (evaluate_transition)
      • auxiliary trace transition constraints (evaluate_aux_transition)

Dependencies

~1.5–3MB
~69K SLoC