HDSLedger

Introduction

HDSLedger is a simplified permissioned (closed membership) blockchain system with high dependability guarantees. It uses the Istanbul BFT consensus algorithm to ensure that all nodes run commands in the same order, achieving State Machine Replication (SMR) and guarantees that all nodes have the same state.

Requirements

• Java 17 - Programming language;

• Maven 3.8 - Build and dependency management tool;

• Python 3 - Programming language;

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Configuration Files

Node configuration

Can be found inside the resources/ folder of the Service module.

{
    "id": <NODE_ID>,
    "isLeader": <IS_LEADER>,
    "hostname": "localhost",
    "port": <NODE_PORT>,
    "clientPort": <CLIENT_PORT>,
    "bizantineType": <BIZANTINE_TYPE>,
    "messageDelay": <MESSAGE_DELAY>
}

Client Configuration

Can be found inside the resources/ folder of the Client module.

{
    "id": <CLIENT_ID>,
    "hostname": "localhost",
    "port": <NODE_PORT>,
    "byzantineType": <BIZANTINE_TYPE>
}

The id field is the unique identifier of the node or client. It shouldn't be repeated!

Dependencies

To install the necessary dependencies run the following command:

./install_deps.sh

This should install the following dependencies:

• Google's Gson - A Java library that can be used to convert Java Objects into their JSON representation.

Puppet Master

The puppet master is a python script puppet-master.py which is responsible for creating keys for all the processes (clients and nodes) and starting the nodes of the blockchain. The script runs with kitty terminal emulator by default since it's installed on the RNL labs.

To run the script you need to have python3 installed. The script has arguments which can be modified:

• terminal - the terminal emulator used by the script
• client_config - a string from the array client_configs which contains the possible configurations for the clients
• server_config - a string from the array server_configs which contains the possible configurations for the blockchain nodes

Run the script with the following command:

python3 puppet-master.py

Note: You may need to install kitty in your computer

Tests

After running the script 'puppet-master.py' you will be prompted to choose a test to run. For the clients the tests are:

1. Regular - A regular test with no faults
2. Over Spend - Clients attempted to spend more money than their account balance.
3. Over Access Clients attempted to transfer funds from one account to itself disguised as another account.
4. Double Spend - Clients tried to spend the same funds twice.

For the server the tests are:

1. Regular - A regular test with no faults
2. Fake Leader - A test where one of the nodes is a fake leader
3. Message Delay - A test where all the nodes have different message delays
4. Leader Delay - A test where the leader has a message delay, and as consequence, there is a round change
5. Round Change with Previous Prepare - A test to check if the system can handle a round change when there was already a prepare message from some nodes
6. Leader with fake signature - A test to check if the nodes verify signatures from received messages
7. Fake Balance Response - A test to check if the client ignores a fake balance response from a bizantine node
8. Byzantine Broadcast - A test to send different order of transactions to each node during the consensus process, attempting to create inconsistencies in the system state

The tests can be made mixed up. For example, you can choose to do Double Spend test on client with Leader with fake signature test on nodes.

Maven

It's also possible to run the project manually by using Maven.

Instalation

Compile and install all modules using:

mvn clean install

Execution

Run without arguments

cd <module>/
mvn compile exec:java

Run with arguments

cd <module>/
mvn compile exec:java -Dexec.args="..."

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This codebase was adapted from last year's project solution, which was kindly provided by the following group: David Belchior, Diogo Santos, Vasco Correia. We thank all the group members for sharing their code.