Security & encryption
CairnVault is designed so that the privacy of your vault does not depend on trusting us. Here is how, in plain English.
When you set up your vault you choose a master password and save a Secret Key. Together, on your own device, they derive your Vault Key — the key that unlocks everything. That Vault Key is never sent to CairnVault. We receive only the already-encrypted result.
The derivation uses Argon2id, a deliberately slow, memory-hard algorithm that makes guessing your password by brute force impractical.
Every item you record is wrapped in its own XChaCha20-Poly1305 encrypted envelope on your device before it is stored, and uploaded documents are encrypted the same way. What our servers hold is ciphertext — an unreadable blob without your key. A server breach, a subpoena, or an insider would find nothing but that blob, because we cannot decrypt it.
Access for your survivors is split two ways. The secret needed to release your vault is divided into two shares: one is wrapped to your designated contact’s key, the other to CairnVault’s key. Opening the vault requires both shares, so neither your contact acting alone nor CairnVault acting alone can ever unlock it.
Each share is protected with a hybrid X25519 + ML-KEM-768 key exchange. X25519 is today’s well-tested standard; ML-KEM-768 is a post-quantum scheme (NIST FIPS 203, ratified 2024) chosen to resist a future quantum-capable adversary who might record encrypted shares now to try to crack them later. Because it is a hybrid, an attacker would have to defeat both.
Your vault is not handed out on request. A survivor files a claim with a death certificate; the claim passes a verification and cooling-off step before any release is approved. Only then are the two shares brought together — on your survivor’s own device, never on our servers — to unlock the vault.
Before your survivor’s device decrypts anything, it verifies that the release was genuinely signed for your plan (a signed-release check). A release that is not properly signed is refused — a safeguard against a forged or tampered handoff.
By design, CairnVault never has access to any of the following:
What we do hold is described in our : your email address and the encrypted ciphertext of your vault. And because a plan for the end of a life has to outlast the company that stores it, our commit us, if we ever wind down, to six months’ notice and a full export of your plan.
This page describes CairnVault’s security architecture in plain language. It is not a security certification or a warranty; no internet service can be guaranteed perfectly secure. Please use a strong master password and safeguard your Secret Key.