blocker

custom UTXO blockchain implementation from scratch

features

• ED25519 crypto for keys and signatures
• UTXO transaction model
• Protobuf encoding
• gRPC transport (p2p gossip between nodes)
• Proof of Stake (PoS) consensus — round-robin, event-driven
• Wallet CLI — create wallet, query balance/transactions, send coins
• Block validation — height, prevHash, proposer, signature, UTXO double-spend

run the network

# Start 3 validator nodes
make run

Nodes will bootstrap, connect to each other, and produce blocks only when there are transactions to include.

cli

# Create a new wallet (prints 64-char seed + address)
make cli create

# Query balance for an address
make cli balance <hex-address>
make cli -node :4000 balance 36f8343eaa41afbff509addde0f5cb4a0691295b

# Query transactions for an address
make cli txs <hex-address>

# Send coins (uses your private key seed + recipient address + amount)
make cli send <your-priv-key-seed> <recipient-address> <amount>
make cli send 0f71b4d... 72974c1... 100

genesis

The genesis block allocates 1000 coins to a fixed address derived from the hardcoded seed. This is the address you can spend from in the demo:

Address: 36f8343eaa41afbff509addde0f5cb4a0691295b

not production-ready (high-level gaps)

this is a learning project. a production blockchain would need at least the following:

consensus

• weighted proposer selection — validators chosen by stake amount, not equal round-robin
• fork choice rule — pick the heaviest/best chain when forks occur
• block finality — blocks are not final; reorgs can happen at any time
• slashing — no economic penalties for double-signing or invalid blocks
• validator rotation — validator set is hardcoded; no dynamic join/leave

networking

• block sync for late joiners — new nodes starting behind the tip never catch up
• out-of-order block buffering — blocks received too far ahead are dropped, not buffered
• peer scoring / banning — no mechanism to disconnect or penalize bad peers
• connection encryption — gRPC runs without TLS

data layer

• persistent storage — everything is in-memory; restart loses all data
• state snapshots / pruning — chain grows forever, no old state cleanup
• merkle proofs — can't prove inclusion of a tx to a light client

transactions / vm

• no smart contracts / VM — only simple value transfers
• fixed fees — no fee market or gas pricing
• no nonce / replay protection — same tx can be replayed unless UTXO is spent

tooling

• no block explorer — no way to inspect chain state visually
• no metrics / monitoring — no prometheus, health checks, or alerts