Signing systems
MPC signing
HSMs
Multisig
Review the full path from key generation to recovery.
We review signing, custody architecture, and operating procedures, including emergency access and vendor dependencies.
Technology coverage
Signing and custody systems we review.
We follow keys from generation through signing, backup, and recovery, checking who can authorize each operation.
Key lifecycle
Key generation
Key storage & backups
Key rotation
Key recovery
Operational controls
Approval policies
Key ceremonies
Emergency access
Vendor integrations
This list is not exhaustive.
Discuss your custody setup.
Describe how you store keys, approve signing, and recover access.
What we review
Follow authority from creation to recovery.
1. Generate
Entropy, ceremonies, share or key creation, devices, participants, and evidence.
2. Store & distribute
HSMs, MPC shares, backups, physical controls, cloud dependencies, and separation.
3. Request
Transaction origination, policy inputs, destination controls, limits, screening, and integrity.
4. Approve
Identity, role separation, quorum, out-of-band checks, escalation, and exceptions.
5. Sign & broadcast
Signer behavior, transaction verification, tamper resistance, endpoint trust, and submission.
6. Monitor & reconcile
Alerts, logs, chain monitoring, settlement, reconciliation, and investigation.
7. Recover & break glass
Backup restoration, compromised devices, disaster recovery, emergency access, and post-event control.
Timing
When this work fits
Review an existing model
Challenge the architecture, implementation, procedures, and production controls around an operating stack.
Design or integrate a model
Support vendor selection, workflow design, role definition, integration, migration, and go-live readiness.
Walk critical scenarios
Examine compromise, insider abuse, vendor failure, data corruption, recovery, and break-glass paths.
Our approach
How we review signing and custody.
Build the custody threat model
Map where keys and shares live, who can use them, and which assumptions depend on vendors. Document credible compromise and failure scenarios.
Trace signing and recovery flows
Follow approvals, signing, recovery, and emergency access. Record the security properties each flow must preserve and the controls responsible for them.
Test controls and document walkthroughs
Examine code, configuration, and procedures in scope. Walk through insider abuse, vendor failure, and recovery scenarios, recording evidence and steps your team can rehearse.
Verify changes and document conclusions
Provide remediation guidance and always verify fixes through retesting. Tie the principal’s signed opinion to the reviewed architecture, procedures, and supporting evidence.
What you receive
What your team receives.
Findings report
Technical and operational gaps, ranked by impact and by how easily someone reaches them.
Threat model
Who can move value, what stands in their way, and the failure paths we consider credible. The register includes scenarios blocked by existing controls.
Record of flows and security properties tested
Signing, approval, recovery, and break-glass, each with the property it has to hold when a human is under pressure.
Invariant register
Each security property, the controls assessed, and supporting evidence.
Control tests and walkthroughs
Documented signing, approval, and recovery scenarios your team can rehearse again.
Signed opinion on the reviewed baseline
The principal’s conclusions, tied to the reviewed architecture, procedures, and evidence.
Your review team
Meet the specialists
A principal leads each engagement. Your proposal names the specialists assigned to the scope.
Piotr Cielas
Principal Advisor
Head of Security at Agora, responsible for security, data protection, and corporate IT risk. Earlier at EY, led assessments across financial services, healthcare, and government.
Michal Bajor
Specialist Advisor
Security specialist with 60+ Web3 reviews across DeFi, L1s, bridges, oracles, and other critical infrastructure. At Kraken, worked on the security of funding services, custody, APIs, and on-chain systems.
Timur Güvenkaya
Founder & Partner
Led a security engineering practice for Rust and non-EVM systems across Substrate and NEAR. Earlier, built vulnerability-detection engines at Invicti used by Fortune 50 and public-sector organizations.
FAQ
Frequently asked questions
Do you verify fixes?
Yes. We always provide remediation guidance and verify fixes through retesting. The final report records the remediation status and any unresolved findings.
Do you review MPC, HSM, and multisig models?
Yes. Scope covers the mechanism and the identity, devices, policy, quorum, integration, backups, recovery, monitoring, and procedures around it.
Can you review a third-party custody platform?
Yes. We can examine vendor assumptions, configuration, APIs, policy, transaction workflows, recovery, monitoring, and retained controls.
Is this a technical or operational review?
Usually both. Custody failures cross architecture, software, identity, process, people, vendor, and recovery boundaries.
Can you help before we choose a vendor?
Yes. The design path compares trust models, operating implications, control ownership, integration risk, and exit constraints.
Do you perform key ceremony exercises?
Key ceremony design, rehearsal, and readiness can be included or delivered through Training & Security Exercises.
Do you need access to private keys or signing shares?
Start with architecture, policies, configuration, and operating procedures. If the review includes code, we need access to it during scoping. Do not send production private keys or signing shares with your inquiry. We agree the access and test setup needed for any signing or recovery exercises during scoping.
Related services
Other ways we can help
Secure Architecture & Process Design
Design or assess critical systems, workflows, integrations, and operating controls before implementation or a major change.
Explore 
Technical Training & Security Exercises
Choose training on Rust, Substrate, and NEAR, or workshops, tabletop exercises, and key-ceremony rehearsals tailored to your systems.
Explore 
Risk Assessment
Give leadership a prioritized view of where security risk concentrates and what to address first.
ExploreDiscuss your custody review.
Describe your custody model, planned changes, and deadline. We will identify the review or design scope.
Discuss your scope