DepChain - Highly Dependable Systems (2024-2025)

Overview

DepChain is a simplified permissioned blockchain system with high dependability guarantees. This project is developed iteratively in two stages:

• Stage 1: Focuses on the consensus layer, specifically implementing a version of the Byzantine Read/Write Epoch Consensus algorithm.
• Stage 2: Targets the transaction processing layer, introducing a smart contract system for managing transactions (in ISTCoin token) and a native cryptocurrency DepCoin

Features

• Static system membership with a pre-defined leader.
• Use of symmetric session keys and Public Key Infrastructure (PKI) for secure identity verification.
• Implementation of the Byzantine Read/Write Epoch Consensus algorithm.
• Support for Byzantine behavior among blockchain members and clients.
• UDP-based network communication with abstraction layers.
• Client interface for submitting transactions and state getters.

Project Structure

contract/
│── artifacts-json/                 # Artifacts generated by the Solidity compiler
│── AccessControl.sol               # Access control smart contract
│── ISTCoin.sol                     # ERC20 token smart contract
depChain/
│── src/                        
│   ├── main/
|   |   ├── java/
│   |   |   ├── depchain/
│   |   |   |   ├── account/        # EOA and Smart contract accounts implementation
│   |   |   |   ├── blockchain/     # Blockchain related classes
│   |   |   |   ├── client/         # Client CLI for submitting transactions and the respective commands
│   |   |   |   ├── consensus/      # Byzantine Read/Write Epoch Consensus implementation
│   |   |   |   ├── library/        # Client library for submitting transactions
│   |   |   |   ├── network/        # UDP-based communication and message handling logic
│   |   |   |   ├── utils/          # Utility classes and helper functions
|   |   |   ├── resources/
|   |   |   |   ├── blocks/         # Contains the genesis block and other nodes' execution state
|   |   |   |   ├── config/         # Configuration files for several byzantine behaviors
|   |   |   |   ├── keys/           # Cryptographic keys
│   ├── test/
│   |   ├──  java/
│   |   |   ├── depchain/           # Unit and integration tests for the system
|   test.py                         # Test script for running the system
README.md                           # Project description and usage guide
report.pdf                          # Project report

Installation and Setup

Prerequisites

• Java Development Kit (JDK) 17+
• Maven

Build and Run

To build the project:

mvn clean install

To run the system:

python3 ./depChain/test.py

Configuration

Environment variables can be set in the .env file located in the root directory. The following variables are available:

• CONFIG_FILE_PATH: Path to the behavior configuration file.
• KEYS_FOLDER_PATH: Path to the folder containing cryptographic keys.
• DEBUG: Enable/disable debug mode.
• BLOCKS_FOLDER: Path to the folder containing the persisted blocks.
• TRANSACTIONS_THRESHOLD: Number of transactions to be processed in a block.

Formatting

To format the code according to the project's style guide:

mvn formatter:format

Testing

To run unit and integration tests:

mvn test

The test suite includes:

• Functional correctness tests for the consensus algorithm.
• Network reliability tests.
• Byzantine behavior simulations.

Usage

You can run each behavior test individually by changing the CONFIG_FILE_PATH environment variable in the .env file for the desired configuration file located in the src/main/java/resources/config/ directory.

Afterwards, run the test script:

python3 test.py

NOTE: you might need to first install tmux:

sudo apt install tmux -y

Then you can interact with the blockchain as a client:

Design Considerations

• Safety & Liveness: The system ensures safety under all conditions and guarantees liveness only if the leader remains correct.
• Client-Consensus Integration: The client submits requests that are transformed into consensus proposals.
• Security: Cryptographic operations ensure message authentication and integrity.

Future Work

• Implementing leader election and dynamic membership.
• Expanding transaction processing capabilities.
• Enhancing fault tolerance and security measures.

Contributors

• Guilherme Leitão - ist199951
• Simão Sanguinho - ist1102082
• José Pereira - ist1103252

Group 12 - 2024/2025

Project developed for the Highly Dependable Systems course at Instituto Superior Técnico, University of Lisbon.

References

[1] Introduction to Reliable and Secure Distributed Programming. 2nd Edition. [2] Springer Computer Science Proceedings Guidelines: https://www.springer.com/gp/computer-science/lncs/conference-proceedings-guidelines