Security model
What we can see. What we cannot.
DeadSwitch uses a zero-knowledge architecture. Our servers never see your vault contents. Here is what that means in practice.
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Encrypted before it leaves your hands
Every item is encrypted on your device with a key derived from your master password. The drive holds ciphertext. So does the optional cloud.
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What the server knows, and what it never sees
It holds your email and a hash of your account password, your beneficiaries’ names and contact details, encrypted key shares, check-in timestamps, and, for cloud vaults, item metadata such as category, size, and who each item is assigned to, plus the file names of documents and recordings. It never sees your master password, your encryption key, or the contents of anything in the vault.
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Two security modes
Key Split, the recommended mode, splits each beneficiary’s secret between their printed card and our server; neither half alone can unlock anything. Cloud Stored keeps the full secret with us, encrypted, and needs no card. That mode trades some of this protection for convenience.
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If our server is breached
In Key Split an attacker gets encrypted key shares that are useless without the physical card, plus hashed passwords and contact details. In Cloud Stored we hold the beneficiary secret, encrypted. In neither mode do they get your master password or anything you stored in the vault.
- Vault data
- AES-256-GCM-SIVNonce-misuse-resistant authenticated encryption
- Key derivation
- Argon2id · 128 MiB · 3 passesMemory-hard; resists GPU brute force
- Media files
- XChaCha20-Poly1305192-bit random nonces, per-file keys
- Database
- SQLCipherEncrypted SQLite at rest on the drive
- Key shares
- XOR split · 128-bit card secretCard half never stored server-side
- Account password
- scrypt hashThis is the account password, not the vault master password
- Release links
- Single-use · 30-day expiryLock permanently after five wrong codes
- Updates
- Ed25519-signedUnsigned or mismatched builds are refused
Read the full security model. Found something? Responsible disclosure: security@dead-switch.com
Key Split and Cloud Stored
Key Split is the recommended mode. Each beneficiary’s secret is split: one half on a printed card you hand them, the other on our server, encrypted. Neither half alone can unlock anything.
Cloud Stored keeps the full beneficiary secret with us, encrypted, and needs no card. It is simpler for someone who might lose a card. It trades some of this protection for convenience. We say that on purpose.
If our server is breached
In Key Split, an attacker gets encrypted key shares that are useless without the physical card, plus hashed passwords and contact details. In Cloud Stored, we hold the beneficiary secret, encrypted. In neither mode do they get your master password or vault contents. A stolen USB without the master password is a brick.
Libraries, not an open-source app
Vault encryption uses standard, publicly documented algorithms and audited open-source libraries (RustCrypto aes-gcm-siv, chacha20poly1305 and argon2 on the drive; @noble/ciphers and @noble/hashes in the browser; SQLCipher for the database). The DeadSwitch application itself is not published.
Responsible disclosure: security@dead-switch.com. Full write-up: app.dead-switch.com/docs/security-model.