Microsoft SEAL

Microsoft SEAL is an open-source (MIT licensed) homomorphic encryption library developed by Microsoft. It allows performing additions and multiplications on encrypted integers or real numbers.

Key features include:

• BFV and BGV schemes: Used for modular arithmetic on encrypted integers where exact values are required.
• CKKS scheme: Used for additions and multiplications on encrypted real or complex numbers, providing approximate results. This is ideal for machine learning models or summing real numbers.

Note: Microsoft SEAL 4.4.0 is a critical security update addressing untrusted-input handling, native memory safety, and managed/native interoperability. All users should upgrade to this version immediately.

Microsoft SEAL is built using CMake. You can perform an out-of-source build on all supported platforms.

Requirements:

• Windows: Visual Studio 2022 with C++ CMake Tools.
• Linux: Clang++ (>= 5.0) or GNU G++ (>= 6.0), CMake (>= 3.22).
• macOS/iOS: Xcode toolchain (>= 9.3), CMake (>= 3.22).
• Android: Android Studio.
• FreeBSD: CMake (>= 3.22).

Note: Compiling with Clang++ provides better runtime performance than GNU G++ on Linux.

Basic Build Steps: Assuming you are in the SEAL directory:

cmake -S . -B build
cmake --build build

Output binaries are located in build/lib/ and build/bin/.

You can use the vcpkg dependency manager to install Microsoft SEAL on most platforms. Note that the C++ library requires C++17.

To install, clone the vcpkg repository, bootstrap it, and then install the seal port. You can also select optional features using the seal[<feature>,...] syntax.

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh  # ./bootstrap-vcpkg.bat for Windows
./vcpkg integrate install
./vcpkg install seal

To create a NuGet package for use in .NET projects, you must first compile both the SEAL and SEAL_C projects using CMake, and then build the dotnet\src\SEALNet.csproj project. Once the binaries are compiled, use the NuGet command line tool to pack the package.

Prerequisites:

1. Compiled SEAL and SEAL_C projects via CMake.
2. Built dotnet\src\SEALNet.csproj.
3. Installed NuGet command line tool.

cd dotnet\nuget
nuget pack SEALNet.nuspec -properties Configuration=Release -Verbosity detailed -OutputDir Release
cd ..\..

The easiest way to build XCFrameworks for iOS is using the provided CMake script. This builds for both device (iphoneos) and simulator (iphonesimulator) targeting arm64.

Release build (outputs to project root):

cmake -P cmake/ios_xcframework.cmake

Debug build (custom output directory):

cmake -DBUILD_TYPE=Debug -DOUTPUT_DIR=./out -P cmake/ios_xcframework.cmake

Once generated, include libseal-4.4.xcframework and libsealc-4.4.xcframework in your Xcode project as framework dependencies.

For .NET developers, a multiplatform NuGet package is available.

Important Notice: No further releases of Microsoft SEAL will be published to NuGet.org. The existing package Microsoft.Research.SEALNet remains available but will not be updated to match newer versions of Microsoft SEAL. To use a newer version in a .NET project, you must build your own NuGet package from source.

Mobile Support (MAUI):

• The .NET wrapper works only on 64-bit platforms.
• Supported Android ABIs: arm64-v8a, x86_64.
• Supported iOS: arm64 for devices and arm64 for the iOS simulator (Apple Silicon Mac hosts only).

If Microsoft SEAL is compiled with ZLIB or Zstandard support, compression is used automatically for serialization (defaulting to Zstandard if both are available).

To explicitly disable compression, pass compr_mode_type::none to serialization methods.

Security Note: The compression rate of a SecretKey can theoretically reveal information about the key. If this is a security concern, save the SecretKey in an uncompressed form.

After creating the NuGet package, copy it from dotnet\nuget\Release to a local directory. To use this package in Visual Studio, you must add that directory as a package source:

1. Open Visual Studio and select Tools / Options....
2. Navigate to NuGet Package Manager / Package Sources in the left pane.
3. In the right pane, add a new package source pointing to the directory where you copied the NuGet package.
4. Once configured, you can add the package to your project by right-clicking your project in Solution Explorer, selecting Manage NuGet packages..., and choosing the Microsoft.Research.SEAL package.

After building the library, you can install it to your system.

Global Installation (requires root/administrator privileges):

cmake -S . -B build
cmake --build build
sudo cmake --install build

Local Installation (e.g., to a specific directory): To install to a custom path like ~/mylibs/:

cmake -S . -B build -DCMAKE_INSTALL_PREFIX=~/mylibs
cmake --build build
sudo cmake --install build

Microsoft SEAL can be installed using platform-specific package managers:

• macOS: Use Homebrew.
• FreeBSD: Use pkg install seal to install security/seal.