Secure communication link between medical apparatuses of a data-management device

A system consisting of at least one medical apparatus and a data management device, wherein the data management device has an app installed, in which measured physiological values and/or therapy parameters can be saved, entered and/or processed,

• wherein data can be exchanged between the data management device and the at least one medical apparatus via a wireless Bluetooth link, and wherein the Bluetooth link is configured to be securely established with additional end-to-end encryption by the at least one medical apparatus and the data management device communicating to carry out at least the following steps:
• out-of-band transmitting of a public key of a pair of keys from the medical apparatus and of device information from the medical apparatus to the data management device, with the transmitting not taking place via Bluetooth;
• setting up of an established and encrypted Bluetooth data communication link between the medical apparatus and the data management device;
• transmitting of a public key of a pair of keys of the data management device from the data management device to the medical apparatus via the established and encrypted Bluetooth link;
• calculating a combined key on the data management device from the transmitted public key of the medical apparatus and a secret key of the pair of keys of the data management device;
• calculating the same combined key on the medical apparatus from the transmitted public key of the data management device and a secret key of the pair of keys of the medical apparatus;
• and
• setting up an end-to-end encrypted link between the medical apparatus and the data management device using the combined key with end-to-end encrypted data being transmitted over the established and encrypted Bluetooth link.