SaferSafes Release

Overview

SaferSafes is a combined Safe extension that provides both liveness module and timelock guard functionality in a single contract. It can be enabled simultaneously as both a module and a guard on a Safe multisig wallet.

Safe Version Compatibility: Safe 1.4.1 only

Components

LivenessModule2

Enables challenge-based ownership transfer to a fallback owner when Safe owners become unresponsive.

Configuration:

• livenessResponsePeriod: Duration Safe owners have to respond to a challenge
• fallbackOwner: Address that can initiate challenges and receive ownership

Flow:

1. Fallback owner calls challenge()
2. Safe owners have livenessResponsePeriod to call respond()
3. If no response, fallback owner calls changeOwnershipToFallback() to become sole owner

TimelockGuard

Enforces transaction delays and allows a subset of signers to cancel scheduled transactions.

Configuration:

• timelockDelay: Required delay before transaction execution (max 365 days)

Flow:

1. Schedule transaction via scheduleTransaction() with required signatures
2. Wait for timelock delay to pass
3. Execute transaction through Safe
4. Optionally cancel with cancelTransaction() using cancellation threshold signatures

Cancellation Threshold: Starts at 1, increases after each cancellation, resets after successful execution.

Critical Invariant

When both components are enabled, the liveness response period must be at least 2x the timelock delay:

if (livenessResponsePeriod < 2 * timelockDelay) {
    revert SaferSafes_InsufficientLivenessResponsePeriod();
}

This ensures the Safe can always respond to a challenge even when transactions are timelocked.

Changelog

v1.1.0

• Audit fixes

v1.0.0

• Initial implementation
• Combined liveness module and timelock guard functionality
• Challenge-based ownership transfer via LivenessModule2
• Transaction scheduling with configurable timelock via TimelockGuard
• Anti-griefing cancellation threshold mechanism
• FREI-PI invariant validation for combined configuration