Currently Communication Navigation and Surveillance (CNS) in civil aviation are undergoing huge changes in the framework of the European SESAR and the US NextGEN research initiatives. One goal is to develop the Future Communication Infrastructure (FCI) for civil aviation, consisting of AeroMACs for airport communications, SatCOM for remote domains, and LDACS for long-range wireless digital communications. The trend towards digitalization is supposed to solve the problems of capacity shortage, frequency saturation and automated data processing. Due to the digitalization process in communication itself and especially in critical infrastructure a strong request for cybersecurity support was raised. Therefore, a threat-and-risk analysis for LDACS was performed resulting in a first cybersecurity architecture specification draft. This paper goes one step further, presenting a suitable set of algorithms and protocols for security support for LDACS. The set is evaluated performance and security wise to match the cybersecurity architecture specification identified in earlier work.