Shamir’s Secret Sharing (SSS): The Math of Backup Redundancy
The Executive Verdict
Introduction: The 'Half-Sheet' Fallacy
Common Error: Writing 12 words on one page and 12 on another. Result: A thief with one half only needs to guess 12 words, achievable with consumer GPUs. Professional Solution: SSS splits the 'Secret' without weakening the 'Security' by using polynomial interpolation.
1. The Math: Polynomial Secrets
Imagine a graph. To define a line, you need 2 points. To define a parabola, you need 3. SSS places the secret at the vertex. With 3 points (shares), the curve is locked and the secret revealed. With 2 points, the curve wobbles infinitely. Zero information is leaked.
A graph showing 5 colored dots on a curved line. Animation: 2 dots = wobbly line. 3 dots = solid line revealing the Key.
2. SSS vs. Multi-Sig: Know the Difference
Multi-Sig is On-Chain (Daily Ops, Transaction Signing). SSS is Off-Chain (Disaster Recovery, Key Reconstruction). Use Multi-Sig for payments; use SSS to back up the individual keys of the Multi-Sig signers.
3. The SLIP-0039 Standard: Shamir Backup
Why SLIP-0039? 1. Interoperability (Trezor/Keystone compatible). 2. Checksums (Prevents typos in backup words). 3. Groups (Allows '2-of-Execs' AND '1-of-Legal' logic).
4. Operational SOP: Distributing the Shards
3-of-5 Map: 1. CEO (Home Safe); 2. Institution (Bank Vault); 3. Auditor (CPA Firm); 4. Legal (General Counsel); 5. Geo-Backup (Swiss Vault). Result: No single person or location holds the key.
5. The 'Steel' Requirement: Physical Durability
Paper rots and burns. Standard: Etch into 316L Marine-Grade Stainless Steel. Fireproof (2500°F), Corrosion-proof, and Tamper-Evident (Sealed with numbered zip-ties).
6. The Audit Trail: The 'Shard Census'
Shards are 'dead' (offline). Audit them physically every 90 days. 1. Request photo of seals from Lawyer/CPA. 2. Visit Bank Vault. 3. Log serial numbers. Ensure shards exist without reading them.
7. The Recovery Ceremony: The 'Break-Glass' Protocol
High Risk Event. Protocol: 1. Clean Room (Offline machine, air-gapped). 2. Witness Quorum (3 holders present). 3. The Wipe (Destroy machine after recovery). Directive: Recovery is Rotation. Move funds to new keys immediately.
8. Case Study: The 'Lost Co-Founder' Rescue
A hostile co-founder held 1 key. CEO lost his key. Startup locked out. Rescue: Reconstructed CEO's key using SSS shards held by Lawyer + Bank. Funds moved, company saved. SSS is internal insurance.
Conclusion: Math > Memory
Relying on memory or paper is Retail. Redundancy is Institutional. SSS allows the board to recover capital even if the office burns and the CEO is lost. Standard: Never manual split. Use SLIP-0039. Etch in steel.
F.A.Q // Logical Clarification
Can a hacker 'guess' missing shards?
"No. SSS is Information-Theoretically Secure. 2-of-3 provides zero math advantage."
Do all signers need SSS?
"Primary Treasury Keys: Yes. Daily Warm Wallets: Optional (Cloud backups maybe ok)."
Is SSKR the same?
"SSKR is the tech name; SLIP-0039 is the standard. They are effectively the same ecosystem."
Can I use an app for this?
"No. Apps = Malware risk. Shards must remain Analog (Steel) or isolated in Hardware."
Module ActionsCW-MA-2026
Institutional Context
"This module has been cross-referenced with Operations & Security / Recovery & Disaster Management standards for maximum operational reliability."