HEIR: Homomorphic Encryption Intermediate Representation

What is HEIR?

HEIR is a compiler toolchain for fully homomorphic encryption (FHE). We aim to standardize a set of intermediate representations related to FHE, which compiler engineers, hardware designers, and cryptography researchers can build upon to accelerate the research and development of production-strength privacy-first software systems.

HEIR is built in the MLIR framework.

For an overview of the project’s goals, see our talk at FHE.org.

Project Goals

  • Provide MLIR dialects for all modern FHE schemes.
  • Design MLIR dialects that appropriately abstract across the many flavors of related schemes.
  • Design lower-level dialects for optimizing underlying abstract-algebraic operations (e.g., modular polynomial arithmetic).
  • Provide hardware accelerator designers an easy path to integrate, so that a wide variety of FHE programs, optimizations, and parameter choices can be compared across accelerators.
  • Provide a platform for research into novel FHE optimizations.
  • Provide a platform for benchmarking.
  • Provide integrations with multiple front-end languages, such as ClangIR and TensorFlow.


TODO(b/287634511): add list of partner companies and universities

The HEIR codebase and documentation are maintained by Google.

Last modified February 23, 2024: Add link to HEIR talk to website (b85bd76a)