Anonymous Governance Meets Safe Multisig: Nethermind's Audit of SAMM Protocol

Introduction

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The Safe Anonymous Mail Module (SAMM) is a specialized module integrated into Safe multisig wallets to enhance transaction privacy and simplify management. Built as a custom app within the Safe Wallet interface, SAMM enabled anonymous interactions between participants using the Noir language.

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The system worked through an email-based voting process. Emails were received by the relayer, containing either propositions for transactions or votes for processing execution of already proposed transactions. The relayer then processed these messages and stored all the votes. After the threshold was reached, a ZK proof was generated and posted on-chain to a SAMM contract. Once the proof was successfully verified, the transaction was executed using the Safe wallet.

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Noir provides a more user-friendly and high-level approach to building zero-knowledge applications compared to Circom, making it easier to write, understand, and maintain.

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Our Process: A Security Review Built for Privacy

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Nethermind Security conducted a full audit of the SAMM circuits in what marked our first major Noir language audit. This presented unique challenges as we were among the first auditing firms to tackle Noir circuits - we and one other company audited in parallel, with no previous audit experiences to reference.

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Despite this uncharted territory, Oxorio's exceptional documentation quality significantly streamlined our process. The audit included comprehensive documentation review, NatSpec analysis, and direct collaboration with the client to address questions that arose during this pioneering security assessment.

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Findings That Mattered

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The audit revealed several areas requiring attention across the SAMM circuits, including operational challenges and security considerations that needed to be addressed through the development process.

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The Outcome: Security Through Collaboration

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The comprehensive audit identified several issues across the SAMM circuits, which were fully addressed through collaborative efforts with the client.

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"Nethermind’s security team combines rigorous technical depth with responsive, human-first communication: live walkthroughs of each finding, practical mitigation paths, and follow-up checks until the fixes were rock-solid. It was an enjoyable experience for us, and the SAMM’s codebase now is measurably safer."

Co-founder and CTO Alex Avdonin.

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”Oxorio, the development team behind SAMM, demonstrated exceptional preparation for this audit. Their high-quality documentation significantly reduced the complexity of the auditing process, showcasing their commitment to security and transparency from the development phase.”

Lead Auditor, Luciana Silva

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Nethermind Security

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We partner with ambitious teams to validate complex cryptographic systems. Ready to discuss your security needs? Start a conversation with Nethermind Security today.