TLaaS (LEX) — License State Machine Specification with Formal Verification

1. Purpose

Define a mathematically verifiable finite state machine (FSM) for license lifecycle management in TLaaS (LEX). Ensure every possible state transition is valid, deterministic, and compliant with TLAAS (DLA) enforcement rules and DAL governance directives.

2. Design Principles

• Deterministic State Flow: No ambiguous or cyclic transitions.
• Formal Verification: Use tools like Certora, Scribble, and SMT solvers to prove correctness.
• Governance Integration: Allow DAL-controlled state overrides under defined emergency conditions.
• Security-First: Disallow unauthorized or illegal state changes at the contract level.

3. State Definitions

Issued → PendingRenewal → Renewed → Issued
Issued → Suspended → Revoked → Archived
Issued → Revoked → Archived
PendingRenewal → Revoked → Archived

4. State Transition Rules

• Issued → PendingRenewal: Triggered by nearing expiry date.
• PendingRenewal → Renewed: Triggered by payment & compliance check.
• Suspended → Revoked: Triggered by compliance violation.
• Revoked → Archived: Final irreversible state.
• Archived: No further transitions allowed.

5. Solidity FSM Implementation

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract LicenseFSM {
    enum State { Issued, PendingRenewal, Renewed, Suspended, Revoked, Archived }
    mapping(bytes32 => State) public licenseStates;

    modifier validTransition(bytes32 id, State newState) {
        require(_isValidTransition(licenseStates[id], newState), "Invalid transition");
        _;
    }

    function _isValidTransition(State from, State to) internal pure returns (bool) {
        if (from == State.Issued && (to == State.PendingRenewal || to == State.Suspended || to == State.Revoked)) return true;
        if (from == State.PendingRenewal && (to == State.Renewed || to == State.Revoked)) return true;
        if (from == State.Renewed && to == State.Issued) return true;
        if (from == State.Suspended && to == State.Revoked) return true;
        if (from == State.Revoked && to == State.Archived) return true;
        return false;
    }

    function transition(bytes32 id, State newState) external validTransition(id, newState) {
        licenseStates[id] = newState;
    }
}

6. Formal Verification Process

• Property 1: No illegal transitions.
• Property 2: Archived state is terminal.
• Property 3: All states are reachable under legal rules.
• Tooling: Certora Prover, Echidna, Mythril.

7. Integration with TLAAS & DAL

• TLAAS (DLA): Triggers automated transitions based on compliance results.
• DAL: Can propose and approve new transition rules.

8. Operational Runbook

• Re-run formal proofs before every contract upgrade.
• Maintain a transition change log in IPFS/Arweave.
• Review governance overrides quarterly.

9. Acceptance Criteria

• All state transitions provably safe.
• 100% formal verification coverage.
• Zero unauthorized transitions in production.

Next Article: License Metadata & Schema Registry Architecture