SRS-based automatic secure device pairing on audio channels

Secure device pairing is necessary to communicate securely between mobile devices. Although several researches have been conducting, it was hard to prevent MITM attack on the wireless communication channel. The reason is that because secure device pairing assumes that participants in communication have never met before, they cannot share some information for detecting MITM attack before starting communication. SAS-based AKA(Authenticated Key Agreement) protocol could prevent MITM attack efficiently using an authenticated channel(e.g. OOB channel). The later researches are focused on improving usability than security or efficiency of a protocol. The reason is that authenticated channel in SAS-based AKA protocol needs user's help, so unintended failures of key agreement can be arisen. Automatic pairing can solve the problem but related research is not abundant. In this paper, we propose a key agreement protocol using SRS(short random string). We also implement the automatic secure device pairing protocol based on audio channel and analyze usability and security.