bellperson

This is a fork of the great bellman library.

bellman is a crate for building zk-SNARK circuits. It provides circuit traits and primitive structures, as well as basic gadget implementations such as booleans and number abstractions.

Backend

There are currently two backends available for the implementation of Bls12 381:

• paired - pure Rust implementation
• blstrs - optimized with hand tuned assembly, using blst

They can be selected at compile time with the mutually exclusive features pairing and blst. Specifying one of them is enough for a working library, no additional features need to be set. The default for now is pairing, as the secure and audited choice.

GPU

This fork contains GPU parallel acceleration to the FFT and Multiexponentation algorithms in the groth16 prover codebase under the compilation feature gpu, it can be used in combination with pairing or blst.

Requirements

• NVIDIA or AMD GPU Graphics Driver
• OpenCL

( For AMD devices we recommend ROCm )

Environment variables

The gpu extension contains some env vars that may be set externally to this library.

• BELLMAN_NO_GPU

  Will disable the GPU feature from the library and force usage of the CPU.

  // Example
  env::set_var("BELLMAN_NO_GPU", "1");

• BELLMAN_VERIFIER

  Chooses the device in which the batched verifier is going to run. Can be cpu, gpu or auto.

  Example
  env::set_var("BELLMAN_VERIFIER", "gpu");

• BELLMAN_CUSTOM_GPU

  Will allow for adding a GPU not in the tested list. This requires researching the name of the GPU device and the number of cores in the format ["name:cores"].

  // Example
  env::set_var("BELLMAN_CUSTOM_GPU", "GeForce RTX 2080 Ti:4352, GeForce GTX 1060:1280");

• BELLMAN_CPU_UTILIZATION

  Can be set in the interval [0,1] to designate a proportion of the multiexponenation calculation to be moved to cpu in parallel to the GPU to keep all hardware occupied.

  // Example
  env::set_var("BELLMAN_CPU_UTILIZATION", "0.5");

Supported / Tested Cards

Depending on the size of the proof being passed to the gpu for work, certain cards will not be able to allocate enough memory to either the FFT or Multiexp kernel. Below are a list of devices that work for small sets. In the future we will add the cuttoff point at which a given card will not be able to allocate enough memory to utilize the GPU.

Device Name	Cores	Comments
Quadro RTX 6000	4608
TITAN RTX	4608
Tesla V100	5120
Tesla P100	3584
Tesla T4	2560
Quadro M5000	2048
GeForce RTX 2080 Ti	4352
GeForce RTX 2080 SUPER	3072
GeForce RTX 2080	2944
GeForce RTX 2070 SUPER	2560
GeForce GTX 1080 Ti	3584
GeForce GTX 1080	2560
GeForce GTX 2060	1920
GeForce GTX 1660 Ti	1536
GeForce GTX 1060	1280
GeForce GTX 1650 SUPER	1280
GeForce GTX 1650	896
gfx1010	2560	AMD RX 5700 XT

Running Tests

To run the multiexp_consistency test you can use:

RUST_LOG=info cargo test --features gpu -- --exact multiexp::gpu_multiexp_consistency --nocapture

Considerations

Bellperson uses rust-gpu-tools as its OpenCL backend, therefore you may see a directory named ~/.rust-gpu-tools in your home folder, which contains the compiled binaries of OpenCL kernels used in this repository.

License

Licensed under either of

• Apache License, Version 2.0, |LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.