How Your Master Key Works: Zero-Knowledge Explained Without Jargon

Your vault is encrypted and decrypted on your own device, using a key that is derived from your passphrase and never sent to LifeWyn. We store the sealed result and nothing that could open it. This is what zero-knowledge means here: we operate the service without the ability to read what is in it.

The rest of this page is how that actually works, because a security claim you cannot examine is just a slogan.

When you unlock your vault, your device runs your passphrase through a deliberately slow key-derivation function together with a random salt. Slow is the feature: it makes guessing passphrases expensive for anyone who ever got hold of the sealed data, without being noticeable to you once per session.

The result is a key-encrypting key. It is never stored and never transmitted. It exists in your browser only for as long as your vault is unlocked, and its only job is to unseal the next key in the chain.

Your passphrase does not directly encrypt your data. Instead, a separate random data key is generated once, and your passphrase-derived key is used to seal it. That sealed data key is the envelope LifeWyn stores. When you unlock, your device unseals the data key and uses it to work with your contents.

This indirection is what makes changing your passphrase cheap. A new passphrase re-seals the same data key; your actual contents are never re-encrypted. It is also what lets a recovery phrase work — the same data key can be sealed a second time under the phrase, giving you an independent way back in.

From the data key, LifeWyn derives further keys — one per category, and one per individual asset — so that a given item is protected by a key of its own. Releasing access to one thing therefore never means handing over the key to everything.

This is the property that makes selective disclosure honest. When a rule releases a single asset to a single nominee, or an emergency contact unlocks only the categories you chose, the system can hand over exactly that item's key and no more, because the keys were separated from the start.

On our servers you will find ciphertext, the sealed key envelope, and the metadata needed to run the service — who your nominees are, what your rules say, when you last checked in. What you will not find is your passphrase, your recovery phrase, any of the keys, or anything readable from your vault.

The honest consequence is stated in the recovery guide: because we cannot read your vault, we cannot restore it for you either. Security that only inconveniences attackers is not security. This inconveniences us too, on purpose.