Security of data is of highest importance in applications such as hardware wallet, since it involves dealing with sensitive customer information such as account public keys, cryptocurrency amounts, etc. When wallet is communicating with the computer through USB C interface, communication is wired and nobody can tap into the cable and monitor the data being sent back and forth between the hardware wallet and the computer. This won’t be as straightforward with the wireless Bluetooth communication between the phone and Citadel Wallet. Someone could listen into the wireless communication and know what messages are being sent. Therefore, Bluetooth communication needs to be setup through end to end encryption and initial pairing of Citadel Wallet device and the phone needs to be handled very carefully utilizing latest Bluetooth 5.0+ security features.

To make communication with the phone maximally secure, we integrated a high-end RF chip into our wallet, which is compliant with the latest Bluetooth Low Energy (BLE) 5.3 standard. Chip also embeds a Crypto Cell (CC) capable of Advanced Encryption Standard (AES) symmetric encryption. BLE 5.3 is capable of a pairing method called LE Secure Connections, which uses Federal Information Processing Standards (FIPS) Elliptic Curve Diffie Hellman(ECDH) key generation approach meant to protect against Man-in-the-Middle (MITM) attacks. User phone and Citadel Wallet will need to go through initial three main phases of pairing and bonding to achieve secure authentication and Long Term Key(LTK) generation shared between Phone and the tracker in the process. After successful pairing further authentication and communication will be based on 128-bit AES symmetric encryption algorithm. Citadel Wallet secure RF chip is capable of on the fly encrypt/decrypt operations when communicating over BLE without sacrificing time.

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