LegacyVault - live demo

← All demosLegacyVaultlive demo runs entirely in your browser · nothing uploaded

1. The secret

Sample text is preloaded so the demo runs immediately; edit it freely. Your text is treated as raw UTF-8 bytes and split byte by byte with Shamir secret sharing over GF(256) (AES field, polynomial 0x11b).

Number of shares threshold: 2-of-N (fixed, so "any two" is provable)

Secret bytes: 0 · SHA-256: -

2. Shares

Share	Holder	Bytes	Hex (index byte + y-values)

Every share is 1 index byte plus one GF(256) y-value per secret byte. A single share is one point on a random line; on its own it carries no information about the secret.

3. Reconstruct - choose the shares to combine

Dead-man switch (inactivity)

The countdown is real wall-clock time since the last check-in. It runs while this tab is open; only the tab's own clock is used, and no notification leaves the page.

seconds of inactivity

disarmed

Last check-in: never

Times fired: 0

Beneficiaries (sample names)

Names are sample data; rename them. Beneficiaries 1 and 2 together hold the 2 shares the release needs. No share is allowed to travel alone.

Event log

Time	Event

What runs here, and how to use it

Real: the Shamir split and Lagrange reconstruction are exact GF(256) arithmetic; random coefficients come from crypto.getRandomValues; the SHA-256 fingerprints are computed in the page; the countdown is measured from the browser clock.

Scope: everything runs in this tab — no server, no storage and no messaging, so the shares never leave the page. Reloading the page destroys them, and background-tab throttling can fire a switch late after the tab wakes. A production vault generates each share on its beneficiary's own device and releases through server-side share escrow with an authenticated scheduler and signed notifications; the release below is simulated in-tab and labelled as such.

Threshold note: the safety of the scheme relies on the random coefficients being secret and independent. If you tamper with a share, the hashes will not match and nothing is released.