# Air gap

An air gap is the isolation of a system from external networks so it cannot be reached or exploited remotely. In digital asset custody, the device holding the blockchain signing keys must be isolated; isolating only approval tokens while the signing system stays connected is not an air gap.

## Why the definition is stricter than it sounds

Many products market hardware approval tokens as air-gapped while their signing servers remain online, leaving the keys exposed to network-based exploitation. Regulators in the strictest regimes have converged on the tighter definition: no persistent network connection to the system holding the keys.

Taurus-PROTECT implements the strict definition in two production modes, a technical air gap using a hardware data diode, and a physical air gap with zero network connectivity.

FAQ:

- Are hardware-token approval systems air-gapped? Not by the regulatory definition. If the servers holding the signing keys stay network-connected, the architecture is not air-gapped, whatever the approval tokens are. The air gap must isolate the signing device itself.

Related: https://www.taurushq.com/security/air-gapped-custody/ https://www.taurushq.com/glossary/technical-air-gap/ https://www.taurushq.com/glossary/physical-air-gap/

Learn more: https://www.taurushq.com/glossary/air-gap/