The companion C library for client side encryption in drivers.

See The Integration Guide to integrate with your driver.

See mongocrypt.h.in for the public API reference. The documentation can be rendered into HTML with doxygen. Run doxygen ./doc/Doxygen, then open ./doc/html/index.html.

First build the following dependencies:

1. The BSON library (part of the C driver), consisting of libbson. Build it from source.

   git clone git@github.com:mongodb/mongo-c-driver.git
   cd mongo-c-driver
   mkdir cmake-build && cd cmake-build
   cmake -DENABLE_MONGOC=OFF -DCMAKE_INSTALL_PATH="/path/to/bson-install" -DCMAKE_C_FLAGS="-fPIC" ../
   make -j8 install
   

   This installs the library and includes into /path/to/bson-install. The prefix can be omitted if you prefer installing in /usr/local.

2. OpenSSL (if on Linux).

Then build libmongocrypt:

git clone git@github.com:10gen/libmongocrypt.git
cd libmongocrypt
mkdir cmake-build && cd cmake-build
cmake -DCMAKE_C_FLAGS="-fPIC" -DCMAKE_PREFIX_PATH="/path/to/bson-install" ../
make

This builds libmongocrypt.dylib and test-libmongocrypt, in the cmake-build directory. Note, the CMAKE_PREFIX_PATH must include the path to the BSON library installation directory if it was not the defaults. Also note that if your project will also dynamically link to the BSON library, you will need to add -DENABLE_SHARED_BSON=ON to the cmake command line.

First install Homebrew according to its own instructions. Using Homebrew, install the following dependencies.

brew install mongo-c-driver cmake

Install the XCode Command Line Tools:

xcode-select --install

Then clone and build libmongocrypt:

git clone https://github.com/mongodb/libmongocrypt.git
cd libmongocrypt
cmake -DENABLE_SHARED_BSON=ON .
cmake --build . --target install

Then, libmongocrypt can be used with pkg-config:

pkg-config libmongocrypt --libs --cflags

Or use cmake's find_package:

find_package (mongocrypt)
# Then link against mongo::mongocrypt

For Windows, there is a fixed URL to download the DLL and includes directory: https://s3.amazonaws.com/mciuploads/libmongocrypt/windows/latest_release/libmongocrypt.tar.gz

test-mongocrypt mocks all I/O with files stored in the test/data and test/example directories. Run test-mongocrypt from the source directory:

cd libmongocrypt
./cmake-build/test-mongocrypt

libmongocrypt is continuously built and published on evergreen. Submit patch builds to this evergreen project when making changes to test on supported platforms. The latest tarball containing libmongocrypt built on all supported variants is published here.

If OpenSSL is installed in a non-default directory, pass -DOPENSSL_ROOT_DIR=/path/to/openssl to the cmake command for libmongocrypt.

If there are errors with cmake configuration, send the set of steps you performed to the maintainers of this project.

If there are compilation or linker errors, run make again, setting VERBOSE=1 in the environment or on the command line (which shows exact compile and link commands), and send the output to the maintainers of this project.

The design of libmongocrypt adheres to these principles.

The main reason behind creating a C library is to make it easier for drivers to support FLE. Some consequences of this principle: the API is minimal, structs are opaque, and global initialization is lazy.

We decided against the "have libmongocrypt do everything" approach because it complicated integration, especially with async drivers. Because of this we decided no I/O occurs in libmongocrypt.

The first version of FLE is to get signal. If FLE becomes popular, further improvements will be made (removing mongocryptd process, support for more queries, better performance). libmongocrypt takes the same approach. Making it blazing fast and completely future-proof is not a high priority.

Version numbers of libmongocrypt must follow the format 1.[0-9].[0-9] for releases and 1.[0-9].[0-9]-rc[0-9] for release candidates. This ensures that Linux distribution packages built from each commit are published to the correct location.

Do the following when releasing:

• In the Java binding build.gradle.kts, replace version = "1.0.0-SNAPSHOT" with version = "1.0.0-rc123".
• Commit, create a new git tag, like 1.0.0-rc123, and push.
• In the Java binding build.gradle.kts, replace version = "1.0.0-rc123" with version = "1.0.0-SNAPSHOT" (i.e. undo the change). For an example of this, see this commit and its parent commit.
• Commit and push.