UTT-BFT: a Distributed Payment Infrastructure Implementation over Concord-BFT

Overview of UTT-BFT

UTT-BFT is an implementation of decentralized ecash with accountable privacy.

Overview of Concord-BFT

Concord-bft is a generic state machine replication library that can handle malicious (byzantine) replicas.

Its implementation is based on the algorithm described in the paper SBFT: a Scalable Decentralized Trust Infrastructure for Blockchains.

It is designed to be used as a core building block for replicated distributed data stores, and is especially suited to serve as the basis of permissioned Blockchain systems.

For a real-life integration example, please take a look at Project Concord, a highly scalable and energy-efficient distributed trust infrastructure for consensus and smart contract execution.

Install and Build (Ubuntu Linux 18.04)

Concord-BFT supports two kinds of builds: native and docker.

The native build is strongly recommended.

Native

git clone https://github.com/definitelyNotFBI/concord-bft
cd concord-bft
sudo ./install_deps.sh # Installs all dependencies and 3rd parties
make build -j $(nproc)
cd build && sudo make test

In order to turn on or off various options, you need to change your cmake configuration. This is done by passing arguments to cmake with a -D prefix: e.g. cmake -DBUILD_TESTING=OFF. Note that make must be run afterwards to build according to the configuration. Please see CMakeLists.txt for configurable options.

Select comm module

One option that is worth calling out explicitly is the communication (transport) library.

We support both UDP and TCP communication. UDP is the default. In order to enable TCP communication, build with -DBUILD_COMM_TCP_PLAIN=TRUE in the cmake instructions shown above. If set, the test client will run using TCP. If you wish to use TCP in your application, you need to build the TCP module as mentioned above and then create the communication object using CommFactory and passing PlainTcpConfig object to it.

We also support TCP over TLS communication. To enable it, change the BUILD_COMM_TCP_TLS flag to TRUE in the main CMakeLists.txt file. When running simpleTest using the testReplicasAndClient.sh - there is no need to create TLS certificates manually. The script will use the create_tls_certs.sh (located under the scripts/linux folder) to create certificates. The latter can be used to create TLS files for any number of replicas, e.g. when extending existing tests.

As we used pinned certificates for TLS, the user will have to manually provide these. THey can use the create_tls_certs.sh script as an example.

C++ Linter

The C++ code is statically checked by clang-tidy as part of the CI.
To check code before submitting PR, please run make tidy-check.

Detailed information about clang-tidy checks.

(Optional) Python client

The python client is required for running tests. If you do not want to install python, you can configure the build of concord-bft by running cmake -DBUILD_TESTING=OFF .. from the build directory for native builds, and CONCORD_BFT_CMAKE_BUILD_TESTING=TRUE make for docker builds.

The python client requires python3(>= 3.5) and trio, which is installed via pip.

python3 -m pip install --upgrade trio

Adding a new dependency or tool

Apollo testing framework

The Apollo framework provides utilities and advanced testing scenarios for validating Concord BFT's correctness properties, regardless of the running application/execution engine. For the purposes of system testing, we have implemented a "Simple Key-Value Blockchain" (SKVBC) test application which runs on top of the Concord BFT consensus engine.

Apollo enables running all test suites (without modification) against any supported BFT network configuration (in terms of n, f, c and other parameters).

Various crash or byzantine failure scenarios are also covered (including faulty replicas and/or network partitioning).

Apollo test suites run regularly as part of Concord BFT's continuous integration pipeline.

Please find more details about the Apollo framework here

Run examples

Simple test application (4 replicas and 1 client on a single machine)

Tests are compiled into in the build directory and can be run from anywhere as long as they aren't moved.

Run the following from the top level concord-bft directory:

./build/tests/simpleTest/scripts/testReplicasAndClient.sh

Using simple test application via Python script

You can use the simpleTest.py script to run various configurations via a simple command line interface. Please find more information here

Directory Structure

• bftengine: concord-bft codebase
  • include: external interfaces of concord-bft (to be used by client applications)
  • src: internal implementation of concord-bft
  • tests: tests and usage examples
• threshsign: crypto library that supports digital threshold signatures
  • include: external interfaces of threshsign (to be used by client applications)
  • src: internal implementation of threshsign
  • tests: tests and usage examples
• scripts: build scripts
• tests: BFT engine system tests

Contributing

The concord-bft project team welcomes contributions from the community. If you wish to contribute code and you have not signed our contributor license agreement (CLA), our bot will update the issue when you open a Pull Request. For any questions about the CLA process, please refer to our FAQ. For more detailed information, refer to CONTRIBUTING.md.

Notes

The library calls std::terminate() when it cannot continue in a safe manner. In that way, users can install a handler that does something different than just calling std::abort().

Community

Concord-BFT Slack.

Request a Slack invitation via concordbft@gmail.com.

License

concord-bft is available under the Apache 2 license.