I built this because I was terrified that if I die tomorrow, my family gets nothing. The existing solutions were either trusting a centralized custodian or complex hardware setups.
Shardium is a client-side tool that splits your seed phrase into 3 shards using Shamir's Secret Sharing.
Shard A: You keep.
Shard B: You give to a beneficiary (PDF).
Shard C: We hold (or you self-host).
It works as a dead man's switch: If you are inactive for 90 days (email ping), Shard C is released to your beneficiary. They combine B + C to recover the funds.
The Stack:
secrets.js-grempe for the math.
FastAPI + PostgreSQL backend.
Client-side encryption (seed never hits the network).
It is 100% Open Source and MIT Licensed. You can self-host it for free ($0), or use the managed version.
I'd love your feedback on the security model. Roast my code here: https://github.com/pyoneerC/shardium
ycombinatrix•1mo ago
I keep 2 on different storage media, 1 with a trusted beneficiary, 1 with a different trusted beneficiary.
This does mean that the beneficiaries can collude to rob me tho. But it is simpler than running & trusting some kind of live service imo.
maxcomperatore•1mo ago
you highlighted exactly the "bug" i wanted to patch though: the collusion risk. if beneficiary A and B have a beer together, you get rugged.
the "live service" here acts purely as a time-lock. beneficiaries can't collude to rob you today because the 3rd shard isn't released until the dead man's switch actually triggers. it protects you from your own friends.
ycombinatrix•1mo ago
maxcomperatore•1mo ago