# HEIR: Homomorphic Encryption Intermediate Representation
[](https://securityscorecards.dev/viewer/?uri=github.com/google/heir)
An MLIR-based toolchain for
[homomorphic encryption](https://en.wikipedia.org/wiki/Homomorphic_encryption)
compilers. Read the docs at [the HEIR website](https://heir.dev).
For more information on MLIR, see the [MLIR homepage](https://mlir.llvm.org/).
## Quickstart
There are currently three ways to use HEIR:
- Use [`bazel`](https://bazel.build/) and
[`rules_heir`](https://registry.bazel.build/modules/rules_heir/) with either
the [OpenFHE](https://openfhe.org/) or
[Lattigo](https://github.com/tuneinsight/lattigo) backends.
- Install [OpenFHE](https://openfhe.org/) and use the
[`heir_py`](https://pypi.org/project/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](https://heir.dev/docs/getting_started/) for more details.
## Building from source
This project uses `bazel` for its build system. Install
[bazelisk](https://github.com/bazelbuild/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.
```bash
bazel build //tools:heir-opt
```
Or run an end-to-end test like
```bash
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](https://www.buildbuddy.io/). 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](https://heir.dev/docs/development/bazel/) page for more
example commands and tips on using bazel.
## Supported backends and schemes
| Backend Library | BGV | BFV | CKKS | CGGI |
| --------------- | --- | --- | ---- | ---- |
| OpenFHE | ✅ | ✅ | ✅ | ❌ |
| Lattigo | ✅ | ✅ | ✅ | ❌ |
| tfhe-rs | ❌ | ❌ | ❌ | ✅ |
| Jaxite | ❌ | ❌ | ❌ | ✅ |
Note some backends do not support all schemes.
## Contributing
There are many ways to contribute to HEIR:
- Come to our [monthly meetings](https://heir.dev/community/) to discuss active
work on HEIR and future project directions. The meetings are recorded and
posted to our [blog](https://heir.dev/blog/) and
[YouTube channel](https://www.youtube.com/@HEIRCompiler).
- Come to our [weekly office hours](https://heir.dev/community/) for informal
discussions and debugging help.
- Ask questions or discuss feature ideas in the `#heir` channel on
[the FHE.org discord](https://discord.fhe.org/).
- Work on an issue marked
["good first issue"](https://github.com/google/heir/contribute) or browse
issues [labeled by topic](https://github.com/google/heir/labels).
- Help us understand new FHE research: either
- Read a paper tagged under
[research synthesis](https://github.com/google/heir/labels/research%20synthesis)
and summarize the novel techniques that could be ported to HEIR.
- File new issues under
[research synthesis](https://github.com/google/heir/labels/research%20synthesis)
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:
```text
@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.
<!-- mdformat global-off -->