Microsoft SEAL is a fast and user-friendly homomorphic encryption library created by Microsoft Research. It is written in C++ and works on Windows, Linux, and macOS. The most recent version of Microsoft SEAL is publicly available at https://github.com/Microsoft/SEAL.
Introduction
Microsoft SEAL is an easy-to-use homomorphic encryption library, developed by researchers in the Cryptography Research Group at Microsoft Research. Microsoft SEAL is written in standard C++ and has no external dependencies, making it is easy to compile in many different environments. The current version includes .NET Standard wrappers for the public API.
The first version of Microsoft SEAL was released at the end of 2015 and the library has since then been in constant development with several major releases per year. Microsoft SEAL is licensed under the MIT license and can be downloaded at https://github.com/Microsoft/SEAL.
Homomorphic Encryption
Homomorphic encryption refers to a new type of encryption scheme that allows computations to be directly on encrypted data without requiring decryption first. The result of such encrypted computations remains encrypted and can thus only be interpreted the owner of a secret key (in most cases the data owner). Such functionality can for example enable a cryptographically private cloud storage and computation service. In particular, Microsoft SEAL implements the BFV scheme for encrypted modular arithmetic, and the CKKS scheme for encrypted approximate fixed-precision arithmetic.
Both the BFV and the CKKS scheme are highly performant post-quantum secure RLWE-based homomorphic encryption schemes. Such encryption schemes are currently not standardized by any major standards organization, but a recently launched effort by the HomomorphicEncryption.org group attempts to instead create a consortium standard describing secure parameters, a standard API, and a programming model for several schemes, including the BFV and the CKKS schemes. Microsoft SEAL implements the secure parameters recommended by the standard.
Documentation and Questions
The GitHub repository front page provides a detailed installation guide for multiple platforms. For a hands-on learning experience, Microsoft SEAL contains extensively commented example projects demonstrating core concepts of the library. In addition, the header files contain detailed comments for the public API.
When asking questions it is important to know the specific version of Microsoft SEAL that is being used, as well as seeing the complete code producing the issue. In particular, the values set in the encryption parameters (EncryptionParameters class) are critical to know, as the behavior of the encryption scheme depends totally on these parameters. Before asking your question please look at the highest voted questions under this tag, as these tend to address many of the common issues, misunderstandings, and fundamental challenges in using Microsoft SEAL.
