05 Security model

Vault & Trust

Your secrets, encrypted on your devices, provable without us.

Credentials and secrets stay as ciphertext that only your enrolled, vault-admitted devices can open. Every device gets its own sealed envelope, so removing a laptop actually removes it — the vault key rotates rather than a server merely declining to serve. The design is deliberately checkable rather than promised: your client enumerates the recipient set and the certificate chain locally.

  • 4Working today
  • 4Being built
  • 10Planned
How it works

The mechanism, not the metaphor.

  1. 01 Enroll a device

    A device-generated key is redeemed against an enrollment token for a root-chained certificate.

  2. 02 Admit it

    A separate signed admission record binds that certificate. Enrollment alone grants nothing.

  3. 03 Seal per device

    The epoch key is wrapped into one envelope per admitted device and per recovery principal.

  4. 04 Write a revision

    A fresh record key encrypts the payload and is itself wrapped under the current epoch.

  5. 05 Use, don't export

    Operate performs the signature or the connection inside the daemon. Only Reveal releases bytes.

  6. 06 Revoke and rotate

    A membership change bumps the epoch and rewraps to whoever remains.

What is in it

18 capabilities, and where each one stands.

How a vault is keyed

  • Planned Per-device envelopes

    Each device gets its own wrapped key. No shared per-person key exists anywhere.

  • Planned Vault epoch key

    One key per epoch, rewrapped to exactly the devices allowed right now.

  • Planned Fresh key per revision

    Every write gets its own key, so damage stays compartmentalised.

  • Planned Rotation on membership change

    A removed device cannot read anything written after it left.

  • Being built Frozen record layouts

    Byte-exact formats, so a reader in another language cannot silently drift.

Who a device is

  • Being built Device certificates

    Your devices prove they are yours from a signed certificate.

  • Being built Signed device list, verified offline

    Two devices on one desk trust each other with no server reachable.

  • Planned Admission is its own record

    Joining your account does not grant vault access. Admission is signed separately.

  • Working today Revocation that ends live access

    A revoked device stops asking and stops answering, immediately.

  • Working today Identity across key rotation

    Rotate a device key without re-enrolling or renaming the device.

Using a secret without handing it over

  • Planned Operate, Materialize, Reveal

    Secrets get used without being exported. Export is the exception, not the default.

  • Planned Custody choice per vault

    You pick whether anyone but you can ever recover a given vault.

  • Planned Recovery from twelve words

    Lose every device; a paper phrase opens a new device generation.

  • Planned Team and shared vaults

    Out of scope for the first release, which is one person and several devices.

The wire itself

  • Working today QUIC, encrypted end to end

    Peer-to-peer bytes between your own devices, over TLS 1.3.

  • Working today A relay is a path, not an endpoint

    Works through NATs, and the relay forwards ciphertext it cannot read.

  • Being built Key protection at rest

    Device identity survives a reboot without prompting at cold start.

  • Planned Mobile at-rest encryption

    Local history on phones encrypted under a platform-wrapped root key.

Measured, not asserted

Numbers from tests that ran.

  • Named, frozen

    SHA-256, Ed25519 verify_strict, XChaCha20-Poly1305 and HPKE base X25519-HKDF-SHA256, over seven length-exact record layouts.

  • No envelope exists

    A device that was never admitted has nothing addressed to it — which holds even if that machine is fully compromised.

  • Cannot mint, cannot read

    A fully compromised coordination server can withhold, delay and serve stale state. It cannot mint a device or read a vault.

  • Exactly your devices

    Custody mode is the recipient set itself, signed and validated on every rotation — so your client can enumerate it and say so.

And what it is not

  • Not key escrow, and not "just log in and it works". There is no server-side custody of your keys.
  • Not a per-person key layer. Envelopes are per device, so removing one laptop is not a person-wide reset.
  • Not removal without rotation. We do not call it cryptographic removal when it is only a server declining to serve.
  • Not "an administrator can never read". Where recovery exists, decryption exists — and a service-custodied mode is never called zero-knowledge.

Start with the devices you already own.

Make them work
as one.

The open core is ready to explore. Build your personal device fabric with Xross.

Open-source core · Direct by design · Your devices, your fabric