Academy for LoRaWAN®

There are two reasons for implementing crypto chips in LoRaWAN devices.

1. Secure storage of the Application Key (known as the Network Key in LoRaWAN 1.2.x) and the derived session keys
2. Fast encryption of data without taking up CPU resources

The crypto chip uses the 128-bit Application Session Key (AppSKey) to encrypt the payload. The 128-bit Network Session Key (NwkSKey) is used by the crypto chip to sign the data and compute the Message Integrity Code (MIC).

In a LoRaWAN application, the central processor retrieves data from sensors. The CPU processes the data and sends it to the crypto chip. Next, the crypto chip returns the encrypted data, which is stored or passed on to the LoRaWAN module for transmission. At the receiving end, the encryption protocol and encryption key must be known in order to decrypt the data for evaluation. A similar crypto chip may be dedicated for this task. The following diagram shows both the data path that is currently at the hardware level, as well as a different, possible approach.

Data Paths: Current and Possible