# Security Wireless communication via the Bluetooth Low Energy interface can be encrypted. If the encryption is turned on, then mobile devices that do not have an encryption key compatible with the key, with which the communication is encrypted cannot read any data sent by the logger. Additionally, it is possible to automatically turn off the Bluetooth Low Energy interface after the desired time from starting the logger. Thanks to this, it will not be possible to connect to the logger using devices equipped with the Bluetooth Low Energy interface. Data transmission in the NB-IoT network is encrypted and therefore safe. The data security problem appears at the stage of data transfer via the Internet - between the NB-IoT network and Efento Cloud / user server. NB-IoT is based on the UDP protocol, which is supposed to be lightweight. Adding security features to this protocol (e.g. encryption) increases the size of sent UDP frames, and thus the device's battery consumption. The solution that ensures safe data transmission from the logger to the server is the use of an APN configured by the network operator and a secure tunnel (VPN) configuration between the APN and Efento Cloud / client's server. Then the data is still sent using the light UDP protocol, without increasing energy consumption, and thanks to the use of a tunnel, it cannot be eavesdropped on during its transmission over the public Internet. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.efento.io/nb-iot-loggers/security.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.