Lattigo: lattice-based multiparty homomorphic encryption library in Go

Lattigo is a Go module that implements Ring-Learning-With-Errors-based homomorphic-encryption primitives and Multiparty-Homomorphic-Encryption-based secure protocols. The library features:

• An implementation of the full-RNS BFV, BGV and CKKS schemes and their respective multiparty versions.
• Comparable performance to state-of-the-art C++ libraries.
• Dense-key and sparse-key efficient and high-precision bootstrapping procedures for full-RNS CKKS.
• A pure Go implementation that enables cross-platform builds, including WASM compilation for browser clients.

Lattigo is meant to support HE in distributed systems and microservices architectures, for which Go is a common choice thanks to its natural concurrency model and portability.

Library overview

The library exposes the following packages:

• lattigo/ring: Modular arithmetic operations for polynomials in the RNS basis, including: RNS basis extension; RNS rescaling; number theoretic transform (NTT); uniform, Gaussian and ternary sampling.

• lattigo/bfv: The Full-RNS variant of the Brakerski-Fan-Vercauteren scale-invariant homomorphic encryption scheme. It provides modular arithmetic over the integers.

• lattigo/bgv: The Full-RNS variant of the Brakerski-Gentry-Vaikuntanathan homomorphic encryption scheme. It provides modular arithmetic over the integers.

• lattigo/ckks: The Full-RNS Homomorphic Encryption for Arithmetic for Approximate Numbers (HEAAN, a.k.a. CKKS) scheme. It provides approximate arithmetic over the complex numbers (in its classic variant) and over the real numbers (in its conjugate-invariant variant).

• lattigo/dbfv, lattigo/dbgv and lattigo/dckks: Multiparty (a.k.a. distributed or threshold) versions of the BFV, BGV and CKKS schemes that enable secure multiparty computation solutions with secret-shared secret keys.

• lattigo/rlwe and lattigo/drlwe: common base for generic RLWE-based multiparty homomorphic encryption. It is imported by the lattigo/bfv, lattigo/bgv and lattigo/ckks packages.

• lattigo/examples: Executable Go programs that demonstrate the use of the Lattigo library. Each subpackage includes test files that further demonstrate the use of Lattigo primitives.

• lattigo/utils: Supporting structures and functions.

Versions and Roadmap

The Lattigo library was originally exclusively developed by the EPFL Laboratory for Data Security until its version 2.4.0.

Starting with the release of version 3.0.0, Lattigo is maintained and supported by Tune Insight SA.

Also starting with from version 3.0.0, the module name has changed to github.com/tuneinsight/lattigo/v[X], and the official repository has been moved to https://github.com/tuneinsight/lattigo. This has the following implications for modules that depend on Lattigo:

• Modules that require github.com/ldsec/lattigo/v2 will still build correctly.
• To upgrade to a version X.y.z >= 3.0.0, depending modules must require github.com/tuneinsight/lattigo/v[X]/, for example by changing the imports to github.com/tuneinsight/lattigo/v[X]/[package] and by running go mod tidy.

The current version of Lattigo, (v4.x.x) is fast-evolving and in constant development. Consequently, there will still be backward-incompatible changes within this major version, in addition to many bug fixes and new features. Hence, we encourage all Lattigo users to update to the latest Lattigo version.

See CHANGELOG.md for the current and past versions.

Stability

To keep a comprehensive history, we prioritize rebases over merges for branches other than main. Branches with the prefix dev_ are branches in active development and will be frequently rebased. Hence, we don't recommend depending on them.

Pull Requests

External pull requests should only be used to propose new functionalities that are substantial and would require a fair amount of work if done on our side. If you plan to open such a pull request, please contact us before doing so to make sure that the proposed changes are aligned with our development roadmap.

External pull requests only proposing small or trivial changes will be converted to an issue and closed.

Support and Issues

The GitHub issues should only be used for bug reports and questions directly related to the use or the implementation of the library. Any other issue will be closed, and for this we recommend the use of GitHub discussions or other topic-specific forums instead. Any new issue regarding an unexpected behavior of the library or one of its packages must be accompanied by a self-contained main.go reproducing the unwanted behavior.

License

Lattigo is licensed under the Apache 2.0 License. See LICENSE.

Contact

If you want to contribute to Lattigo, to contact us directly or to report a security issue, please do so using the following email: [email protected].

Citing

Please use the following BibTex entry for citing Lattigo:

@misc{lattigo,
    title = {Lattigo v4},
    howpublished = {Online: \url{https://github.com/tuneinsight/lattigo}},
    month = Aug,
    year = 2022,
    note = {EPFL-LDS, Tune Insight SA}
}

References

1. Efficient Bootstrapping for Approximate Homomorphic Encryption with Non-Sparse Keys (https://eprint.iacr.org/2020/1203)
2. Bootstrapping for Approximate Homomorphic Encryption with Negligible Failure-Probability by Using Sparse-Secret Encapsulation (https://eprint.iacr.org/2022/024)
3. Somewhat Practical Fully Homomorphic Encryption (https://eprint.iacr.org/2012/144)
4. Multiparty Homomorphic Encryption from Ring-Learning-With-Errors (https://eprint.iacr.org/2020/304)
5. An Efficient Threshold Access-Structure for RLWE-Based Multiparty Homomorphic Encryption (https://eprint.iacr.org/2022/780)
6. A Full RNS Variant of FV Like Somewhat Homomorphic Encryption Schemes (https://eprint.iacr.org/2016/510)
7. An Improved RNS Variant of the BFV Homomorphic Encryption Scheme (https://eprint.iacr.org/2018/117)
8. Homomorphic Encryption for Arithmetic of Approximate Numbers (https://eprint.iacr.org/2016/421)
9. A Full RNS Variant of Approximate Homomorphic Encryption (https://eprint.iacr.org/2018/931)
10. Improved Bootstrapping for Approximate Homomorphic Encryption
11. Fully Homomorphic Encryption without Bootstrapping (https://eprint.iacr.org/2011/277)
12. Homomorphic Encryption for Arithmetic of Approximate Numbers (https://eprint.iacr.org/2016/421)
13. A Full RNS Variant of Approximate Homomorphic Encryption (https://eprint.iacr.org/2018/931)
14. Improved Bootstrapping for Approximate Homomorphic Encryption (https://eprint.iacr.org/2018/1043)
15. Better Bootstrapping for Approximate Homomorphic Encryption (https://eprint.iacr.org/2019/688)
16. Post-quantum key exchange - a new hope (https://eprint.iacr.org/2015/1092)
17. Faster arithmetic for number-theoretic transforms (https://arxiv.org/abs/1205.2926)
18. Speeding up the Number Theoretic Transform for Faster Ideal Lattice-Based Cryptography (https://eprint.iacr.org/2016/504)
19. Gaussian sampling in lattice-based cryptography (https://tel.archives-ouvertes.fr/tel-01245066v2)

The Lattigo logo is a lattice-based version of the original Golang mascot by Renee French.