libmongocrypt

The companion C library for client side encryption in drivers.

Documentation

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.

Building libmongocrypt

First build the following dependencies:

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

   git clone https://github.com/mongodb/mongo-c-driver
   cd mongo-c-driver
   mkdir cmake-build && cd cmake-build
   cmake -DENABLE_MONGOC=OFF -DCMAKE_INSTALL_PREFIX="/path/to/bson-install" ../
   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 https://github.com/mongodb/libmongocrypt
cd libmongocrypt
mkdir cmake-build && cd cmake-build
cmake -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.

Installing libmongocrypt on macOS

Install the latest release of libmongocrypt with the following.

brew install mongodb/brew/libmongocrypt

To install the latest unstable development version of libmongocrypt, use brew install mongodb/brew/libmongocrypt --HEAD. Do not use the unstable version of libmongocrypt in a production environment.

Building libmongocrypt from source on macOS

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

Installing libmongocrypt on Windows

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

To download the latest unstable release, download from this URL: https://s3.amazonaws.com/mciuploads/libmongocrypt/windows/latest_release/libmongocrypt_unstable.tar.gz Do not use the unstable version of libmongocrypt in a production environment.

Testing

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.

Troubleshooting

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.

Design Principles

The design of libmongocrypt adheres to these principles.

Easy to integrate

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.

Lightweight

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.

Narrowly scoped

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.

Releasing

Version number scheme

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.

Steps to release

Do the following when releasing:

• Update CHANGELOG.md with any new changes and update the [Unreleased] text to the version being released.
• 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.
• Create the release from the GitHub releases page from the new tag.
• Submit a PR to update the Homebrew package https://github.com/mongodb/homebrew-brew/blob/master/Formula/libmongocrypt.rb

Installing libmongocrypt From Distribution Packages

Distribution packages (i.e., .deb/.rpm) are built and published for several Linux distributions. The installation of these packages for supported platforms is documented here.

Unstable Development Distribution Packages

To install the latest unstable development package, change 1.0 to development in the package URLs listed in the subsequent instructions. For example, https://libmongocrypt.s3.amazonaws.com/apt/ubuntu <release>/libmongocrypt/1.0 in the instructions would become https://libmongocrypt.s3.amazonaws.com/apt/ubuntu <release>/libmongocrypt/development. Do not use the unstable version of libmongocrypt in a production environment.

.deb Packages (Debian and Ubuntu)

First, import the public key used to sign the package repositories:

sudo sh -c 'curl -s https://www.mongodb.org/static/pgp/libmongocrypt.asc | gpg --dearmor >/etc/apt/trusted.gpg.d/libmongocrypt.gpg'

Second, create a list entry for the repository. For Ubuntu systems (be sure to change <release> to xenial or bionic, as appropriate to your system):

echo "deb https://libmongocrypt.s3.amazonaws.com/apt/ubuntu <release>/libmongocrypt/1.0 universe" | sudo tee /etc/apt/sources.list.d/libmongocrypt.list

For Debian systems (be sure to change <release> to stretch or buster, as appropriate to your system):

echo "deb https://libmongocrypt.s3.amazonaws.com/apt/debian <release>/libmongocrypt/1.0 main" | sudo tee /etc/apt/sources.list.d/libmongocrypt.list

Third, update the package cache:

sudo apt-get update

Finally, install the libmongocrypt packages:

sudo apt-get install -y libmongocrypt-dev

.rpm Packages (RedHat, Suse, and Amazon)

RedHat Enterprise Linux

Create the file /etc/yum.repos.d/libmongocrypt.repo with contents:

[libmongocrypt]
name=libmongocrypt repository
baseurl=https://libmongocrypt.s3.amazonaws.com/yum/redhat/$releasever/libmongocrypt/1.0/x86_64
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/libmongocrypt.asc

Then install the libmongocrypt packages:

sudo yum install -y libmongocrypt

Amazon Linux 2

Create the file /etc/yum.repos.d/libmongocrypt.repo with contents:

[libmongocrypt]
name=libmongocrypt repository
baseurl=https://libmongocrypt.s3.amazonaws.com/yum/amazon/2/libmongocrypt/1.0/x86_64
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/libmongocrypt.asc

Then install the libmongocrypt packages:

sudo yum install -y libmongocrypt

Amazon Linux

Create the file /etc/yum.repos.d/libmongocrypt.repo with contents:

[libmongocrypt]
name=libmongocrypt repository
baseurl=https://libmongocrypt.s3.amazonaws.com/yum/amazon/2013.03/libmongocrypt/1.0/x86_64
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/libmongocrypt.asc

Then install the libmongocrypt packages:

sudo yum install -y libmongocrypt

Suse

First, import the public key used to sign the package repositories:

sudo rpm --import https://www.mongodb.org/static/pgp/libmongocrypt.asc

Second, add the repository (be sure to change <release> to 12 or 15, as appropriate to your system):

sudo zypper addrepo --gpgcheck "https://libmongocrypt.s3.amazonaws.com/zypper/suse/<release>/libmongocrypt/1.0/x86_64" libmongocrypt

Finally, install the libmongocrypt packages:

sudo zypper -n install libmongocrypt