Distributed Blockchain Synchronization

University Projects #Distributed Computing#Python

Overview#

A distributed computing application that builds and validates a blockchain by requesting blocks from peers. This application was built in Python and uses Sockets to send requests and receive responses from peers.

You can view the full project here.

Key Achievements#

Implemented GOSSIP protocol for peer discovery
Built consensus mechanism that correctly identifies and syncs to longest chain
Handled out-of-order block delivery through storage and reordering
Maintained synchronization through periodic consensus (every 2 minutes)
Responded to peer requests including BLOCK, CONSENSUS, STATS_REPLY, and GOSSIP_REPLY

Implementation#

Network#

Implemented sockets to perform peer-to-peer communication
Build GOSSIP protocol for peer discovery
Handled peer timeout (1 minute inactivity) and removal
Maintained peer list through keep-alive messages (every 30 seconds)

Consensus#

Requested STATS from all known peers to determine chain heights
Identified longest chain using max(height,hash) comparison
Broke longest chain ties by counting peers reporting the same (height, hash)
Requestd blocks round-robin from all peers with longest chain

Block Validation#

Validated nonce length (max 40 characters)
Verified message count (max 10 per block)
Checked message length (max 20 characters per message)
Confirmed hash follows predefined rules

Protocol Details#

Joining Network#

Send GOSSIP to 3 random peers
Reply to unknown GOSSIP IDs via GOSSIP_REPLY
Start keep-alive timer to timeout peers that don’t GOSSIP_REPLY within 1 minute
Begin consensus process

Local Block Synchronization#

Request STATS from all known peers
Wait for STAT_REPLYs
Identify longest chain and which peers have it
Request blocks round-robin from peers with longest chain
Validate blocks and add blocks to local chain
Handle ANNOUNCEMENTs of newly mined blocks via block validation

Network Block Synchronization#

Perform consensus on local chain before sending STATS_REPLY to peers
Do consensus every 2 minutes to ensure local chain synchronized with network chain