Show HN: Shardium – open-source "Dead Man's Switch" for crypto inheritance(shardium.xyz)
shardium.xyz
Show HN: Shardium – open-source "Dead Man's Switch" for crypto inheritance
https://www.shardium.xyz/
6 comments
I prefer to do a 4 shares / 2 needed for recovery.
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.
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.
running 4-of-2 definitely removes the service dependency.
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.
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.
You should consider highlighting that this can be used for way more than crypto wallets. The seed phrase can be used to restore a GPG key, a FIDO2 authenticator including SSH/WebAuthn, etc.
100%. i actually use it for my gpg keys too. i need to make that clearer on the landing page so it doesn't look like a "crypto-only" tool. recovering ssh/fido2 backups is a huge use case. thanks for the feedback
Why not use Vaultwatden for this ? It has a built in dead man switch recovery system.
big fan of vaultwarden (i self-host it).
the main difference is architecture: shardium splits the secret (shamir) so the server never holds the full data, whereas vaultwarden holds the full encrypted vault.
also the "grandma factor": getting non-tech family to setup a vaultwarden account was friction. this is just "find paper in drawer, scan qr".
the main difference is architecture: shardium splits the secret (shamir) so the server never holds the full data, whereas vaultwarden holds the full encrypted vault.
also the "grandma factor": getting non-tech family to setup a vaultwarden account was friction. this is just "find paper in drawer, scan qr".
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