3D Secret Splitting and Reconstruction Tool
Split one secret into exactly three independent shares. All three shares are required to reconstruct it.
A = (0, 0, secret) over the finite field F257. Two uniformly random 3D vectors B and C are generated, and the third share is D = B + C - A (mod 257). Reconstruction uses A = B + C - D (mod 257). Any one share or any pair of shares is statistically independent of the secret, assuming the browser's cryptographically secure random generator works correctly.
Split a secret
Enter text below. For binary data, Base64-encode it first. No data is sent anywhere; the page has no network access.
All three shares are necessary. Keeping two shares together does not reveal the secret, but it reduces the number of independently protected items to one remaining share. A compromised endpoint that sees the original or reconstructed text is outside this scheme's protection.
Reconstruct
Paste the three shares in any order. The tool verifies their format, set identifier, vector ranges, reconstructed structure and an internal SHA-256 digest before displaying the text.
About the tool
This is a strict 3-of-3 secret-sharing tool implemented entirely in the browser. It deliberately avoids floating-point geometry, Math.random(), remote scripts, analytics, cookies and server-side processing.
The secrecy claim is specific: fewer than three valid shares reveal no information about the secret contents in the mathematical model. No browser tool can honestly promise absolute security against a compromised operating system, malicious browser extension, altered page source, clipboard malware, endpoint logging, or an attacker who obtains all three shares.