TLOSGovernanceHSM.sol - DAO-controlled signing key example

[igor53627]

Parent Issue

Closes part of #47

Description

Build a governance-controlled HSM contract where a signing key is embedded in TLOS and can only be used when governance conditions are met.

Use Case (from iO "DAO Signing")

Traditional DAOs use multisig for cross-chain operations. TLOS enables:

• Single signing key hidden in obfuscated circuit
• Key can only sign when on-chain governance predicate passes
• Works like a software HSM with policy enforcement

Example Flow

Governor                         Contract                          External Chain
   |                                |                                    |
   | propose(action)                |                                    |
   |------------------------------->|                                    |
   |                                |                                    |
   | [voting period]                |                                    |
   |                                |                                    |
   | execute(proposalId, puzzle)    |                                    |
   |------------------------------->|                                    |
   |                                | verify vote passed                 |
   |                                | verify puzzle solution             |
   |                                | sign(action) with hidden key       |
   |                                |-------- signature ---------------->|

Key Features

• Embedded ECDSA/Ed25519 signing key (or simpler: output a "signed" hash)
• Governance predicate: vote threshold, timelock, quorum
• Puzzle integration to prevent real-time brute-force during execution
• Signature output for off-chain verification

Security Model

• What's hidden: The signing private key
• What's public: Governance rules, proposals, votes
• Guarantee: 2^76 puzzle + ~2^112 LWE to extract key
• Limitation: NOT for high-value, long-term keys (bridges, treasuries)

Suitable Use Cases

• Low-limit emergency keys
• Governance-only operations (parameter changes)
• Experimental cross-chain signing
• Short-lived keys with rotation

NOT Suitable For

• Bridge keys with significant TVL
• Root governance keys
• Multi-year key lifetimes

Implementation Notes

• Simplified signing: output keccak256(action, hiddenKey) as "signature"
• Real ECDSA would require secp256k1 in circuit (complex, high gas)
• Focus on demonstrating the governance + puzzle pattern

Acceptance Criteria

• Contract compiles and passes tests
• Clear security warnings about key lifetime limits
• Governance flow fully tested
• Gas benchmark documented