Split your secret.
Divide your control file into N shares. Any M can reconstruct it. Give one to your lawyer, one to your partner, one in your safe deposit box. No single person has enough.
Secret to split
Threshold
Enter shares
Paste each share on a separate line. You need at least M shares.
How Shamir's Secret Sharing works.
Your secret is split using polynomial interpolation over a finite field (GF(256)). Each share is a point on a random polynomial of degree M-1. Any M points can reconstruct the polynomial and recover the secret. Fewer than M shares reveal nothing - not even partial information.
This is information-theoretically secure. It's not encrypted. It's mathematically split. Even with M-1 shares, the attacker has zero bits of information about the original.
Use cases.
Crypto inheritance
Split your control file 3-of-5. Give shares to your lawyer, partner, trusted friend, safe deposit box, and a sealed letter. If something happens to you, any 3 can reconstruct access.
Multi-party custody
A fund requires 2-of-3 signers to access cold storage. Split the deny.sh control file the same way. No single party can decrypt alone.
Geographic distribution
Store shares in different countries. A seizure in one jurisdiction can't compromise the secret. You need shares from multiple locations.
Dead man's switch
Give M-1 shares to people you trust. Keep the final share yourself. If you become unreachable, a time-locked share release completes the set.
Client-side. Zero knowledge.
Splitting and combining happen entirely in your browser. Nothing is transmitted. Pair this with seed phrase protection - encrypt first, then split the control file.