FAQ - Frequently Asked Questions

General

What is Shardium?

Shardium is a trustless dead man's switch for crypto inheritance. It splits your seed phrase into 3 shards using Shamir's Secret Sharing, ensuring no single party can access your funds.

Is this safe?

Yes. Shardium uses Shamir's Secret Sharing, which provides information-theoretic security. This means: - 1 shard reveals zero information about your secret - No amount of computing power can change this - It's mathematically proven, not just "hard to break"

Do you ever see my seed phrase?

No. Your seed phrase is split entirely in your browser using JavaScript. We only receive Shard C, which is useless on its own.

What if Shardium gets hacked?

Attackers would only get Shard C values. Without Shard B (which beneficiaries hold physically), they cannot recover any seed phrases.

What if Shardium shuts down?

If we shut down: 1. You still have Shard A 2. Your beneficiary still has Shard B 3. A + B = full recovery

You don't need us to recover your funds.

Using Shardium

How often will I receive emails?

Every 30 days. Just click the link to confirm you're alive.

What if I'm on vacation?

You have 90 days (3 missed checks) before the switch triggers. Most vacations are shorter than this. If you'll be away longer, click the heartbeat link before you go.

Can I change my beneficiary?

Currently, you would need to create a new vault. Beneficiary changes are on our roadmap.

What if my beneficiary dies first?

You should create a new vault with a new beneficiary. Consider having multiple vaults for multiple beneficiaries.

Can I have multiple beneficiaries?

Currently, one beneficiary per vault. For multiple heirs, create multiple vaults with different portions of your holdings.

Recovery

How does my beneficiary recover the funds?

They receive Shard C via email (when switch triggers)
They already have Shard B (the printed PDF you gave them)
They visit the Shardium recovery page
They enter both shards
Original seed phrase is displayed
They import it into a wallet

What if my beneficiary loses Shard B?

This is critical. Without Shard B, they cannot recover even with Shard C. Recommend they: - Store the printed PDF in a safe - Make multiple copies - Store in a bank safety deposit box

Can I recover my own funds?

Yes! You have Shard A. Combine with either: - Shard B (ask your beneficiary) - Shard C (contact Shardium support)

Technical

What cryptographic library do you use?

We use secrets.js-grempe, a well-maintained JavaScript implementation of Shamir's Secret Sharing.

Is the code open source?

Yes! Check our GitHub repository. You can audit the code yourself.

Can I self-host?

Absolutely. Clone the repo and run your own instance. See the self-hosting documentation.

What's the threshold scheme?

We use 2-of-3: 3 shards created, any 2 can recover the secret.

Privacy & Legal

What data do you store?

Your email (for heartbeat notifications)
Beneficiary email (for Shard C delivery)
Shard C (encrypted)
Last heartbeat timestamp

We do NOT store: - Your seed phrase - Shards A or B - Wallet addresses - Any financial information

Yes. You can request deletion of all your data at any time.

What happens to my data if I cancel?

All data is deleted within 30 days of cancellation.

Shardium Docs