Abstract: An air-gapped system enables the secure transfer and control of digital assets, such as those associated with crypto-currency. The system includes an Integration Server for receiving requests from an application interface, a Central Control Center for verifying the requests received and authorizing the requests using digital signatures, and multiple Distributed Data Centers, each including a cold Data Center Hardware Security Module (DC HSM). These DC HSMs securely store and manage cryptographic keys. Each Data Center also includes an offline Processing Unit coupling its DC HSM to a dedicated Remote Controlled Server. The Remote Controlled Server receives requests from the Integration Server and forwards them to the Processing Unit of a DC HSM using a Near-Field Communication (NFC) Interface between the two. Preferably, the NFC interface is physically shielded to resist side channel attacks.