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0.12.3 Nov 30, 2020
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0.2.0 May 20, 2019

#199 in Magic Beans

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Used in 20 crates (12 directly)


13K SLoC

bellperson Crates.io

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.


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.


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.


  • 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.


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

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

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

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

    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
Tesla V100 5120
Tesla P100 3584
Tesla T4 2560
Quadro M5000 2048
GeForce RTX 3090 10496
GeForce RTX 3080 8704
GeForce RTX 3070 5888
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
gfx906 7400 AMD RADEON VII
------------------------ ------- ----------------

Running Tests

To run using the pairing backend, you can use:

RUSTFLAGS="-C target-cpu=native" cargo test --release --all --no-default-features --features pairing

To run using both the gpu and blst backend, you can use:

RUSTFLAGS="-C target-cpu=native" cargo test --release --all --no-default-features --features gpu,blst

To run the multiexp_consistency test you can use:

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


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.


Licensed under either of

at your option.


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.


~121K SLoC