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 (Python)

Pip install the heir_py package

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pip install heir_py

Then run an example:

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from heir import compile
from heir.mlir import I64, Secret

@compile()  # defaults to scheme="bgv", OpenFHE backend, and debug=False
def func(x: Secret[I64], y: Secret[I64]):
    sum = x + y
    diff = x - y
    mul = x * y
    expression = sum * diff + mul
    deadcode = expression * mul
    return expression

func.setup()
enc_x = func.encrypt_x(7)
enc_y = func.encrypt_y(8)
result_enc = func.eval(enc_x, enc_y)
result = func.decrypt_result(result_enc)

print(
  f"Expected result for `func`: {func.original(7,8)}, FHE result:"
  f" {result}"
)

This will compile the function above using the BGV scheme to machine code via
the OpenFHE backend.
Then calling the function will encrypt the inputs, run the function, and return
the decrypted result. The function call foo(7, 8) runs the entire
encrypt-run-decrypt flow for ease of testing.

Building from source

HEIR requires a recent C compiler (see
clang_matrix
for version-specific support, recent GCCs also tend to work), and some backends
like OpenFHE require libomp-dev.

HEIR depends on LLVM (from source) so a clean build may take 15-30 minutes
depending on your machine.

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.

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bazel build //tools:heir-opt

Or run an end-to-end test like

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

See the bazel tips 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 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 in academic work through following entry:

textCopy
@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.

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