Assets
Adversaries and outcomes
What it protects against
- Browser and cloud password leaks — credentials never live in a browser or a cloud vault.
- Malware that scrapes stored passwords — the vault is off-host and encrypted with a key the host never sees.
- Credential theft at rest — dumping the EEPROM yields only ciphertext.
- Cloning — the AES key is device-bound inside the secure element.
- Unsigned/rogue firmware — rejected at boot.
- Online PIN brute force — exponential backoff, re-applied at every boot so it cannot be skipped by power-cycling; the vault is never destroyed by wrong PINs.
What it does not protect against
- A compromised host during use. Keystrokes typed to an infected computer can be captured there. ZeroKeyUSB reduces storage exposure, not the risk of typing into a machine that is already owned by an attacker.
- Plaintext USB backup on an untrusted machine. The export sends credentials in clear text to the host. Perform backups only on a trusted, offline computer.
- Offline PIN cracking after physical bus access. The PIN hash is readable
over I²C (a known trade-off of the secure-element SKU). An attacker who removes
the epoxy and reaches the bus can attempt an offline
SHA-256(PIN ‖ serial)search. Mitigations: the epoxy encapsulation and using a long PIN. There is no destructive self-wipe. - Coercion / shoulder-surfing of the PIN. Standard operational-security concerns apply.
Design consequences for buyers
- Use ZeroKeyUSB on managed or personal machines you trust for the moment of typing; it is strongest exactly where stored-password managers are weakest (shared, infected, unmanaged hosts).
- Treat the backup file as sensitive and generate it offline.
- Choose a long PIN for high-value deployments; it is the last line against a lab-grade physical attack.