Payments & Infra · Private payments vault · 2026Hackathon build
Shroud
A shielded Zcash spending vault where a code-enforced policy engine, not a chatbot, decides when money moves.
- Tests
- 171 across 27 files
- Policy engine
- 12 rules in code
- On-chain
- Real shielded txs
01 The problem
Letting software spend money on your behalf is risky: a prompt injection or a bug can drain the wallet, and every purchase is public on-chain.
Funds sit in a self-hosted, shielded Zcash vault. A chat assistant can browse and request purchases, but a pure TypeScript policy engine decides whether anything is paid, and the assistant has no tool that accepts an address or amount.
02 How it works
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03 What I built
- 01A 12-rule policy engine (caps, rolling budgets, approval thresholds, kill switch) as a pure function.
- 02Shielded payments that carry an encrypted SHRD1 receipt in the same ZIP-321 transaction, readable only with a viewing key.
- 03Real purchases on hack day: Bitrefill eSIMs paid from the vault on Zcash testnet.
- 04171 tests across 27 files.