This paper presents an efficient key management scheme using Return link service in MEOSAR (Medium-Earth Orbit for search and rescue) satellites of COSPAS-SARSAT system. When distress signal is interrupted by environment, the key consistency between the distress beacon and Mission Control Center (MCC) is important. In this paper, we analyze possibility of data communication through return link and propose message structure and encryption method for key initialization of beacon and MCC.

Keywords: COSPAS-SARSAT, return link, encryption, authentication