The present disclosure relates to establishing secure communication between a dialysis machine and a fluid preparation device. In an example, a dialysis machine includes a control unit configured to establish a short-range wireless connection with an external fluid preparation device. The control unit establishes the short-range wireless connection by causing a user interface to display a prompt to enter a passkey associated with a fluid preparation device, using the received passkey to pair with the fluid preparation device, and creating a new bonding table or write to an empty bonding table using the passkey. The control unit is also configured to generate a shared key using the passkey and at least one predetermined criterion and use the shared key to authenticate with the fluid preparation device. When authentication with the fluid preparation device is successful, the control unit enables data communication using the short-range connection with the fluid preparation device.