Shamir Secret Sharing: Advanced Crypto Security
Professional-grade security practices worth learning at any level
🎯 When to Consider Shamir Secret Sharing
While especially valuable for high-net-worth individuals, Shamir Secret Sharing is good security practice for any serious crypto holder. Learn the principles even if you start simple.
You Should Consider This If:
- Any meaningful crypto holdings ($1k+)
- Want to learn professional security practices
- Single wallet loss would hurt financially
- Need inheritance planning
- Want protection against physical attacks
- Desire geographic distribution of risk
- Have trusted parties who could help
- Portfolio worth >$100k (strongly recommended)
WTF is Shamir Secret Sharing?
Named after cryptographer Adi Shamir (the 'S' in RSA), it's a way to split your seed phrase into multiple parts where you need M-of-N parts to recover it.
Example: 3-of-5 Setup
Your seed is split into 5 shares. Any 3 shares can recover the full seed. But 2 shares reveal nothing.
- Share 1: Safety deposit box
- Share 2: Trusted lawyer
- Share 3: Family member
- Share 4: Different country
- Share 5: Home safe
Lose 2 shares? No problem. Get compromised? They need 3 locations.
Why Shamir is Chad-Tier Security
✅ Benefits
- No single point of failure: One location compromised = still safe
- Flexible recovery: Don't need ALL shares
- Geographic distribution: Spread across countries
- Inheritance friendly: Family can recover without full knowledge
- $5 wrench attack resistant: You literally can't access funds alone
- Customizable threshold: 2-of-3, 3-of-5, 5-of-9, whatever
⚠️ Risks
- Complexity: More moving parts = more ways to mess up
- Share management: Need to track multiple locations
- Trust required: Share holders could collude
- Recovery complexity: Harder than single seed
- Implementation errors: Bad tools = compromised setup
- Social engineering: Attackers target share holders
How to Actually Do This
🏆 Method 1: Trezor Model T (Recommended)
Trezor has native Shamir backup built in. No external tools needed.
- Get Trezor Model T (ONLY from trezor.io - never Amazon/eBay)
- Choose "Shamir Backup" during setup
- Select threshold (e.g., 3-of-5)
- Device generates shares on-screen
- Write each share on separate cards
- Distribute shares to secure locations
Method 2: Multisig (Alternative)
Not Shamir, but achieves similar security.
- Use Gnosis Safe (Ethereum)
- 2-of-3 or 3-of-5 signers
- Each signer has different wallet
Battle-Tested Setups by Portfolio Size
$1k - $100k: Learning Setup
2-of-3- Share 1: Home safe or secure location
- Share 2: Trusted family member
- Share 3: Safety deposit box (if available)
Good practice for learning the system with smaller amounts
$100k - $500k: Standard Shamir
2-of-3- Share 1: Home safe
- Share 2: Bank deposit box
- Share 3: Trusted family member
Good balance of security and convenience
$500k - $2M: Geographic Distribution
3-of-5- Share 1: Home safe (your city)
- Share 2: Bank box (your city)
- Share 3: Lawyer's office
- Share 4: Different state/country
- Share 5: Trusted friend/family
Survives natural disasters and local threats
$2M - $10M: Professional Grade
4-of-7- Share 1-2: Multiple bank boxes
- Share 3-4: Law firms (different cities)
- Share 5: Offshore storage
- Share 6-7: Trusted individuals
Consider professional custody services
$10M+: Institutional Level
5-of-9+- Multiple jurisdictions
- Professional custody services
- Legal trusts involved
- Consider Fireblocks/Anchorage
You need a family office at this point
Inheritance: So Your Wife Can Access After You Die
The Dead Man's Switch Setup
3-of-5 Family Setup:
- Share 1: Your home safe (spouse knows)
- Share 2: Spouse's separate location
- Share 3: Family lawyer (instructions in will)
- Share 4: Trusted family member
- Share 5: Bank deposit box (spouse co-signer)
Leave Instructions:
- Letter with lawyer explaining system
- Location of shares (not the shares themselves)
- Which hardware wallet to use
- Contact info for crypto-literate helper
- DO NOT put shares in the will (public record)
How People Mess This Up
🤡 Storing shares digitally
"I'll just encrypt them" = You'll get hacked
🤡 All shares in one country
Government seizure = game over
🤡 Not testing recovery
Find out shares are wrong when it's too late
🤡 Telling people they have shares
Now they're targets for social engineering
🤡 Using online Shamir tools
Congrats, you just gave away your seed
🤡 Buying hardware wallets from Amazon/eBay
Supply chain attacks are real - official websites only
🤡 Too complex threshold
5-of-9 sounds cool until you need to coordinate 5 people
OPSEC for Shamir
- Never photograph shares
Not even "just for backup"
- Different security for each share
Don't use same bank for multiple boxes
- Silent setup
Share holders shouldn't know about other holders
- Regular audits
Check share locations annually
- Decoy shares
Consider fake shares in obvious locations
- Legal protection
Shares in trust = legal framework
Recovery Process (When You Need Access)
- Gather required shares
Need M shares for M-of-N setup
- Secure location
Private room, no cameras, airplane mode
- Use same tool that created shares
Trezor for Trezor shares, etc.
- Enter shares carefully
Double-check each word
- Recover to NEW wallet
Don't reuse compromised setup
- Move funds immediately
To fresh wallet with new seed
- Create new Shamir setup
Old shares are now compromised
The Gigawhale Checklist
📋 Before Setup
- Decide on threshold (start simple: 2-of-3)
- Identify secure locations
- Get Trezor Model T (from trezor.io only)
- Plan inheritance structure
- Consult crypto-aware lawyer
🔧 During Setup
- Use air-gapped device
- No digital copies ever
- Metal backup for shares
- Test recovery immediately
- Document locations (encrypted)
🔄 Ongoing
- Annual share audit
- Update inheritance docs
- Test recovery yearly
- Rotate if compromised
- Stay updated on tools
Shamir Secret Sharing is professional-grade security. Whether you're securing $1k or $1M, these practices will serve you well as your portfolio grows.
Get Trezor Model T for Shamir →