Lurk is currently in Alpha. Code that runs in the Lurk Alpha release is expected to also run in Lurk Beta, and eventually Lurk 1.0. However, some low-level data representations are anticipated to change, and we will be refactoring the circuit implementation to increase auditability and further our confidence in Lurk's cryptographic security. Also note that since Lurk inherits some security properties from the underlying proving system, those who would rely on Lurk should investigate the security and status of Nova itself. We encourage early adopters to begin writing real applications taking advantage of Lurk so you can begin to familiarize themselves with the programming model. Likewise, we welcome your feedback -- which will help ensure ongoing development meets user need.
Note that Groth16 support is only partial, since no trusted setup has been run. If you wish to use Lurk with Groth16, a trusted setup will be required; and we would not recommend undertaking this until the 1.0 circuit has been released.
Lurk is a statically scoped dialect of Lisp, influenced by Scheme and Common Lisp. A reference implementation focused on describing and developing the core language can be found in the lurk repo.
Lurk's distinguishing feature relative to most programming languages is that correct execution of Lurk programs can be directly proved using zk-SNARKs. The resulting proofs are succinct: they are relatively small, can be verified quickly, and they reveal only the information explicitly contained in the statement to be proved.
Lurk's distinguishing feature relative to most zk-SNARK authoring languages is that Lurk is Turing complete, so arbitrary computational claims can be made and proved (subject to resource limitations, obviously). Because Lurk is a Lisp, its code is simply Lurk data, and any Lurk data can be directly evaluated as a Lurk program. Lurk constructs compound data using SNARK-friendly Poseidon hashes (provided by Neptune), so its data is naturally content-addressable.
Integration with backend proving systems and tooling for proof generation are both still very early. Performance and user experience still have room for significant optimization and improvement, but simple examples can be found in the fcomm example directory.
It is an explicit design goal that statements about the evaluation of Lurk programs have identical semantic meaning across backends, with the qualification that Lurk language instances are themselves parameterized on scalar field and hash function. When backends use the same scalar field and hash function, they can be used to generate equivalent proofs. This is because the concrete representation of content-addressed data is fixed.
Lurk backend integration is still immature, so current performance is not representative. As a rough approximation, we estimate that for entirely general computation using Lurk's universal circuit, Nova proving throughput will be on the order of 1,000 iterations per second per GPU. We expect that most compute-heavy applications will use optimized 'coprocessor' circuits, which will dramatically improve performance. Planned improvements to Nova will allow for smaller inner circuits, further improving throughput -- and for full parallelization of reduction proofs.
Lurk's Alpha release has undergone a security audit as of 03/29/2023, performed by Inference.
Please note that the Lurk language and spec will be versioned independently from the crates that implement the spec. This is necessary semantic versioning implies different requirements for the language and its implementation. For example, Lurk Alpha is released as crate lurk 0.2.0. It is our intention for these two versioning systems to coincide at 1.0. The next major Lurk release will be Lurk Beta, but there may be multiple minor-version crate releases before then.
Lurk source files used in tests are in the lurk-lib submodule. You must initialize and update submodules before test will pass:
git submodule update --init --recursive
Lurk can be compiled to Wasm with cargo build --target wasm32-unknown-unknown
cargo run --release
Or use the wrapper script:
bin/lurkrs
Set the environment variable LURK_FIELD to specify the scalar field of the Lurk language instance:
- LURK_FIELD=PALLAS (default): scalar field of Pallas
- LURK_FIELD=VESTA: scalar field of Vesta
- LURK_FIELD=BLS12-381: scalar field of BLS12-381
``
➜ lurk-rs ✗ bin/lurkrs
Finished release [optimized] target(s) in 0.06s
Runningtarget/release/examples/repl`
Lurk REPL welcomes you.
(let ((square (lambda (x) (* x x)))) (square 8)) [9 iterations] => 64
```
Or enable info log-level for a trace of reduction frames:
``
➜ lurk-rs ✗ RUST_LOG=info bin/lurkrs
Finished release [optimized] target(s) in 0.05s
Runningtarget/release/examples/repl`
Lurk REPL welcomes you.
(let ((square (lambda (x) (* x x)))) (square 8)) INFO lurk::eval > Frame: 0 Expr: (LET ((SQUARE (LAMBDA (X) (* X X)))) (SQUARE 8)) Env: NIL Cont: Outermost INFO lurk::eval > Frame: 1 Expr: (LAMBDA (X) (* X X)) Env: NIL Cont: Let{ var: SQUARE, body: (SQUARE 8), savedenv: NIL, continuation: Outermost } INFO lurk::eval > Frame: 2 Expr: (SQUARE 8) Env: ((SQUARE .
env: NIL, continuation: Outermost } INFO lurk::eval > Frame: 3 Expr: SQUARE Env: ((SQUARE . env: ((SQUARE .arg: 8, saved env: NIL, continuation: Outermost } } INFO lurk::eval > Frame: 4 Expr: 8 Env: ((SQUARE . env: ((SQUARE . env: NIL, continuation: Outermost } } INFO lurk::eval > Frame: 5 Expr: (* X X) Env: ((X . 8)) Cont: Tail{ savedenv: NIL, continuation: Outermost } INFO lurk::eval > Frame: 6 Expr: X Env: ((X . 8)) Cont: Binop{ operator: Product, unevaledargs: (X), savedenv: ((X . 8)), continuation: Tail{ savedenv: NIL, continuation: Outermost } } INFO lurk::eval > Frame: 7 Expr: X Env: ((X . 8)) Cont: Binop2{ operator: Product, evaledarg: 8, continuation: Tail{ saved_env: NIL, continuation: Outermost } } INFO lurk::eval > Frame: 8 Expr: Thunk{ value: 64 => cont: Outermost} Env: NIL Cont: Dummy INFO lurk::eval > Frame: 9 Expr: 64 Env: NIL Cont: Terminal [9 iterations] => 64 ```
You can install the lurkrs Repl on your machine with
$ cargo install --path .
Install Nix and enable Nix flakes. Then, you can enter into a Nix devshell with the appropriate dependencies for Lurk with
$ nix develop
or
$ direnv allow
And then build with Cargo as usual:
$ cargo build
MIT or Apache 2.0