Abstract: The invention relates to an injection system in which drug delivery data are transmitted from a drug delivery device to a mobile device via a wireless Bluetooth connection and, from there, to a remote server via a network connection. A novel method makes it possible for the drug delivery data to be encrypted on the drug delivery device and to be sent via the Bluetooth transmission channel without pairing being carried out. The drug delivery data are decrypted only on the remote server and assigned to the drug delivery device. This process can be supported by both the mobile device and the drug delivery device observing the Bluetooth transmission channel and estimating how far away the relevant sender of the transmitted data is from the mobile device or drug delivery device.