Lime

Lime is a C++ library implementing Open Whisper System Signal protocol : Sesame, double ratchet and X3DH. https://signal.org/docs/

Lime can run the Signal Protocol using elliptic curve 25519 or curve 448-goldilocks.

It is designed to work jointly with Linphone[1] in a multiple devices per user and multiple users per device environment.

License

Copyright (c) 2019 Belledonne Communications SARL under GNU GPLv3 (see LICENSE.txt)

The above license excludes the content of src/jni directory Copyright (c) 2016 Mapbox covered by its respective license, see src/jni/LICENSE.txt

Dependencies

• bctoolbox[2] : portability layer, built with Elliptic Curve Cryptography
• soci-sqlite3 : Db access

Build instrucitons

 cmake -DCMAKE_INSTALL_PREFIX=<install_prefix> -DCMAKE_PREFIX_PATH=<search_prefix> <path_to_source>

 make
 make install

Documentation

To generate the Doxygen documentation files(having ran the cmake command):

 make doc

Comprehensive documentation on implementation choices and built-in protocols in lime.pdf

Testing

To test on local machine, you must run a local X3DH server.

• A nodejs/sqlite version of UNSECURE X3DH server is provided in tester/server/nodejs See README from this directory for instructions.

If a local X3DH server is running with default parameter just run

 make test

To launch a particular test suite, use ctest, running:

 ctest -R <Test suite name> [--verbose]

Test suite names are

• crypto: Test the crypto primitives
• double_ratchet: Specific to the Double Ratchet protocol
• hello_world: Basic Lime test, mostly a demo code. Requires a live X3DH server on localhost
• lime: Complete testing of all features provided by the library. Requires a live X3DH server on localhost
• C_ffi: Available only if C interface is enabled, test the C89 foreign function interface
• JNI: Available only if JNI is enabled, test the Java foreign function interface

Library settings

Some mostly harmless settings are available in src/lime_settings.hpp

Library APIs

The C++11 API is available in include/lime/lime.hpp

if enabled (see Options), a C89 FFI is provided by include/lime/lime_ffi.h

if enabled (see Options), a java FFI is provided by Lime.jar located in the build directory in src/java subdirectory

Options

• CMAKE_INSTALL_PREFIX=<string> : installation prefix
• CMAKE_PREFIX_PATH=<string> : prefix where depedencies are installed
• ENABLE_UNIT_TESTS : compile non-regression tests (default YES)
• ENABLE_SHARED : build the shared library (default YES)
• ENABLE_STATIC : build the static library (default YES)
• ENABLE_STRICT : build with strict complier flags e.g. -Wall -Werror (default YES)
• ENABLE_CURVE25519 : Enable support of Curve 25519 (default YES)
• ENABLE_CURVE448 : Enable support of Curve 448 (default YES)
• ENABLE_PROFILING : Enable code profiling for GCC (default NO)
• ENABLE_C_INTERFACE : Enable support of C89 foreign function interface (default NO)
• ENABLE_JNI : Enable support of Java foreign function interface (default NO)

• [1] linphone-desktop: git://git.linphone.org/linphone-desktop.git
• [2] bctoolbox: git://git.linphone.org/bctoolbox.git or http://www.linphone.org/releases/sources/bctoolbox