Cobo Vault is an air-gapped, open source hardware wallet that uses completely transparent QR code data transmissions. Visit the [Cobo Vault official website]( https://cobo.com/hardware-wallet/cobo-vault) to learn more about Cobo Vault.
2. Interaction with the mobile application [Cobo Vault Mobile](https://cobo.com/hardware-wallet/cobo-vault-app) via QR code.
3. Interaction with the Secure Element (SE) via serial port, open source SE firmware can be found at [cobo-vault-se-firmware](https://github.com/CoboVault/cobo-vault-se-firmware). Transaction data is signed by the Secure Element and the generated signature is sent back to the application. This signature and other necessary messages are displayed as a QR code. You can check the animation on our webpage to see the whole process. Users use their mobile or desktop application to acquire signed transaction data and broadcast it.
The hardware wallet application was programmed with Java language. The transaction related work is done by Typescript, for which open source code is available at [crypto-coin-kit](https://github.com/CoboVault/crypto-coin-kit). The J2V8 framework is used as a bridge between Java and Typescript.
1. [crypto-coin-message-protocol](https://github.com/CoboVault/crypto-coin-message-protocol) - protocol buffer of communication with the mobile application