HEIR: Homomorphic Encryption Intermediate Representation

An MLIR-based toolchain for homomorphic encryption compilers. Read the docs at the HEIR website.

For more information on MLIR, see the MLIR homepage.

Quickstart

There are currently three ways to use HEIR:

• Use bazel and rules_heir with either the OpenFHE or Lattigo backends.
• Install OpenFHE and use the heir_py Python package.
• Install HEIR from source and invoke the heir-opt and heir-translate binaries directly, extracting the generated backend code and integrating it into your project manually.

See Getting Started for more details.

Building from source

This project uses bazel for its build system. Install bazelisk to manage the bazel version automatically. Then, with bazel on your path (pointing to bazelisk), run the following to build the main pass-running tool.

bazel build //tools:heir-opt

Or run an end-to-end test like

bazel test //tests/Examples/openfhe/ckks/halevi_shoup_matvec:all

HEIR depends on LLVM (from source) so a clean build may take 30 minutes depending on your machine. For faster builds, use BuildBuddy. Sign up for an account, create an API key, and add the following to .bazelrc.user in the root of the HEIR workspace:

common --remote_header=x-buildbuddy-api-key=<YOUR_API_KEY>
common --config=remote

This should reduce a clean build time to about 5 minutes.

See the bazel tips page for more example commands and tips on using bazel.

Supported backends and schemes

Note some backends do not support all schemes.

Contributing

There are many ways to contribute to HEIR:

• Come to our monthly meetings to discuss active work on HEIR and future project directions. The meetings are recorded and posted to our blog and YouTube channel.
• Come to our weekly office hours for informal discussions and debugging help.
• Ask questions or discuss feature ideas in the #heir channel on the FHE.org discord.
• Work on an issue marked "good first issue" or browse issues labeled by topic.
• Help us understand new FHE research: either
  • Read a paper tagged under research synthesis and summarize the novel techniques that could be ported to HEIR.
  • File new issues under research synthesis to alert us of papers that should be investigated and incorporated into HEIR.

Citations

The HEIR project can be cited in academic work through the following entry:

@misc{ali2025heir,
      title={HEIR: A Universal Compiler for Homomorphic Encryption},
      author={Asra Ali and Jaeho Choi and Bryant Gipson and Shruthi Gorantala
              and Jeremy Kun and Wouter Legiest and Lawrence Lim and Alexander
              Viand and Meron Zerihun Demissie and Hongren Zheng},
      year={2025},
      eprint={2508.11095},
      archivePrefix={arXiv},
      primaryClass={cs.CR},
      url={https://arxiv.org/abs/2508.11095},
}

Support disclaimer

This is not an officially supported Google product.