Audit-Vault

A C++17 blockchain-style audit framework for file access, featuring:

• gRPC-based client/server and peer-to-peer gossip protocols
• RSA digital signatures for end-to-end integrity and non-repudiation
• Merkle-tree block integrity and cryptographic hashing
• Leader election and heartbeat for high-availability consensus
• On-demand block retrieval (GetBlock) for new or recovering nodes
• Persistent mempool, chain.json, and per-block JSON files

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📦 Features

1. Submit & Gossip Audits
   Clients submit FileAudit requests over gRPC; servers persist them to a mempool and gossip to peers.

2. Batch Block Proposal
   The leader periodically collects pending audits, forms a block, computes a Merkle root, and broadcasts a ProposeBlock message.

3. Voting & Commit
   Peers verify each proposal (Merkle root, previous-hash, audit signatures), vote, and upon majority, commit the block (updating chain.json, pruning the mempool, and writing blocks/block_<id>.json).

4. Leader Heartbeats
   Nodes exchange heartbeats every 2 s, tracking each other’s latest block IDs and mempool sizes, and marking peers dead after a 4 s timeout.

5. Leader Election
   When no leader is known or the leader dies, a node triggers an election via TriggerElection/NotifyLeadership RPCs, comparing its own metrics (block ID, mempool size, address) against the candidate to vote.

6. Block Synchronization
   Recovering nodes can request missing blocks (GetBlock) from peers, ensuring they catch up before accepting new proposals.

🛠 Prerequisites

• C++17 compiler (e.g. gcc ≥ 9, clang ≥ 11)
• CMake ≥ 3.15
• gRPC & Protocol Buffers
• OpenSSL (for RSA signing/verification)
• nlohmann/json (header-only)

File Structure

. ├── CMakeLists.txt ├── README.md ├── peers.json # List of peer addresses ├── leader.json # Initial leader, batch size & interval ├── keys/ # RSA keypair for clients ├── proto/ # .proto definitions ├── include/ # Public headers ├── src/ # Implementation (.cpp) files ├── blocks/ # Generated per-block JSON files ├── mempool.dat # Persisted mempool └── chain.json # Persisted blockchain metadata

Building

chmod +x starter.sh build.sh run.sh
./starter.sh
./build.sh

Running

./run.sh

If you want to run the server with a different address run:

cd build
./node_server 0.0.0.0:<port_number>

For running the client:

cd build
./client

Configuration

peer.json:

Put address of all the peer nodes in the array

leader.json:

The leader_addr field is redundant, you can use the batch size, batch_interval_s to determine when to trigger a block creation and proposal.