AirGap Vault
Installed on a smartphone that has no connection to any network
...The AirGap Vault application is installed on a dedicated device that has no connection to any network, thus it is air-gapped. The AirGap Wallet is installed on your everyday smartphone. AirGap Vault is responsible for secure key generation. Entropy from audio, video, touch and accelerometer are used together with the output of the hardware random number generator. The generated secret is saved in the secure enclave of the device, only accessible by biometric authentication. Accounts for multiple protocols can be created. Transactions are prepared by the AirGap Wallet and then transferred to the offline device via QR code, where it is signed and sent back to the Wallet using another QR code.