Guard Firewall is a Sequence-operated review signer that evaluates transactions before they are sent on-chain. It enforces ecosystem policies, performs threat simulations via third-party integrations, and can block or allow transactions by signing or withholding a guard signature. Ecosystem admins can also maintain blacklists of malicious apps or contracts.

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Policy model

Policies are configured per ecosystem and can include:
  • App registration and blacklists: only registered apps/origins may submit; admins can blacklist apps or contracts.
  • Risk thresholds: block transactions that exceed a risk score returned by the simulator.
  • Method and contract allowlists: restrict which contracts and function selectors can be called.
  • Spend limits and token rules: cap per-interval outflows by token, recipient, or app.
  • Emergency kill switch: fail-closed mode that blocks all or specific scopes.

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Threat simulation

Guard can perform real-time threat analysis on the transaction payload (calldata, value, state deltas). Based on the ecosystem configuration, Guard applies policy thresholds and signs or denies the transaction, or requires OTP confirmation.

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Blacklist controls

  • Admins can blacklist apps, origins, or contracts. Blacklists take precedence and cause immediate denials.
  • Lists are propagated to the Guard and cached with short TTL; updates are near-real-time.

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Operational notes

  • Fail-closed: if the Guard is unreachable and policy requires a review signature, transactions are blocked.
  • Auditability: decisions are logged with inputs (hashes), simulator responses, policy version, and reason codes.
  • Performance: caching and incremental simulation are used to keep latency low; timeouts default to deny to avoid bypass.

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Implementation guidance

  • Require a Guard signature in your session or wallet policy so transactions cannot bypass review.
  • Register apps and origins in your ecosystem admin, define policies, and set risk thresholds.
  • Keep blacklists curated and respond quickly to incident intel.