Abstract
This letter improves the confidentiality of visible light communication links by proposing a robust key-generation mechanism for optical orthogonal frequency division multiplexing (OFDM) systems in an indoor environment. In this letter, we propose to generate keys from the bipolar OFDM samples at the output of optical OFDM systems. We suggest to assign a part of cyclic prefix samples located in the region of small channel effect for keys generation during session period. The proposed scheme generates keys for medium access control (MAC) sublayer and physical layer. It provides high computational security against passive eavesdroppers in the physical level, because each signal frame is encrypted by a different key. So, the encryption in MAC level can be turned off without any risk in security. This setting can enhance the system throughput. Also, the implemented method achieves zero bit disagreement rates with key generation on the fly.