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--- name: air-gapped-signing-workflow-for-cold-storage description: Simulates and enforces a strict air-gapped signing workflow (Coordinator -> QR/SD -> Offline Vault -> Sign -> Broadcast) for institutional crypto custody. domain: crypto-custody-security subdomain: Key Management tags: - crypto - custody - security - air-gap - psbt brokers_frameworks: - Generic version: "1.1.0" author: System license: MIT --- ## When to Use Use this skill when designing the architecture for institutional crypto treasury management or securing API withdrawal whitelists. To prevent catastrophic private key theft, high-value signing must never occur on internet-connected machines. This workflow enforces the physical separation of the "Coordinator" (online) and the "Signer" (offline vault), ensuring clear signing without network exposure. ## Prerequisites - Python 3.9+ - Understanding of Partially Signed Bitcoin Transactions (PSBT) or equivalent unsigned payload structures. ## Workflow 1. **Coordinator (Online)**: Algorithm generates an unsigned transaction intent (destination, amount). 2. **Export to Air-Gap**: The unsigned payload is encoded (conceptually via QR code or SD card) to cross the physical air gap. 3. **Signer (Offline)**: The offline vault decodes the payload, performs **Clear Signing** verification (displaying exact intent to hardware screen), and signs with the isolated private key. 4. **Import & Broadcast**: The signed payload is returned across the air gap to the Coordinator for blockchain broadcast. ## Common Pitfalls - **Blind Signing**: The offline device simply signs the payload hash without decoding and verifying the destination address and amount, making it vulnerable to malware on the online coordinator. - **Network Bridging**: Using USB cables, Bluetooth, or WiFi to transfer the payload to the "offline" device, completely defeating the air gap. ## Verification Run `python scripts/test_air_gapped_signing_workflow_for_cold_storage.py` to ensure the strict segregation of online and offline environments and the failure of blind/tampered signatures. ## Related Skills - `hot-cold-wallet-split-for-trading-bots` - `multi-signature-approval-for-large-transfers`