Node Armor

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🛡️ NodeArmor: a shared bank book that survives 80% packet loss

NodeArmor is our entry for the Cryptographic Singularity 6-hour sprint. It is a mesh ledger where nodes pass signed transfers to whoever is in radio range, lose most packets on the way, and still end up with identical books.

Think of a village after a storm. No internet, no bank. Everyone keeps a notebook and shouts notes to neighbours, and most shouts get lost. NodeArmor makes sure all the notebooks end up the same and nobody can cheat.

🎮 Try it out

• Live demo: aevsge.vercel.app
• Code: github.com/akulsaju/aevsge

Buttons to press in the demo:

• Send: a signed payment hops across the mesh.
• Cheat: forge signature: every node rejects the forged payment.
• Cheat: overspend: signed, but more than the sender owns, so it is refused.
• Jam the middle: the network splits, the books diverge, then heal.
• Attack: fake-node flood: a fake node spams forgeries and gets blocked.
• Run automated audit: grades all four rubric items live.

✅ Rubric coverage

🧠 How it works

1. Alice signs a payment with a real ECDSA P-256 key (WebCrypto).
2. The payment is gossiped over a lossy, range-limited radio mesh.
3. Every node checks the signature. Forged, tampered, wrong-key, malformed and overspending transactions are rejected.
4. Valid transactions go into a grow-only set, ordered by Lamport clock then id.
5. Every node computes the same balances from the same set, so replicas converge and a double spend keeps exactly one payment. Total supply stays 650.

📡 Realism

• Range-limited links, distance-based loss and latency
• Draggable and moving nodes, node outages, jammed-middle partitions
• Fake-node flood attack, plus an unsafe mode (signature checks off) to show the damage

🐍 Python reference node

Pure Python, stdlib only: CBOR over UDP, proof stub, per-key LWW CRDT, 80% drop simulation and a trusted-writer Sybil filter.

• sprint_node.py: MeshNode, CBOR codec, proof stub, CRDT merge
• test_sprint.py: tests for CBOR, proofs, partition and convergence under loss
• demo.py: 4-node chaos demo (partition, heal, Sybil injection)

Run it:

python demo.py
node tests/api.test.js

Deploy it:

vercel --prod

The file api/node.js is a Vercel serverless function that re-verifies ECDSA transactions on the server.

⚠️ Honest limits

• Signatures prove who authorised a payment. This is not a zero-knowledge system.
• A double spend is resolved by a fixed tie-break rule, not true global ordering.
• The Python verify_zk_proof is a structural stub. A real ZK-STARK verifier would replace it in production.
• Ledger state is not persisted. Keys are generated fresh on each page load.

Built in a 6-hour sprint 🔥 Mesh. Prove. Converge. Survive.

Built With

• html5
• javascript
• python
• react