The Automatic Identification System (AIS) is a tracking system used in vessels and vessel traffic control services to identify and locate vessels and is being regarded as the main tool for complementing the navigator’s direct visual/audible information augmented with RADAR data to prevent collisions at sea. Despite its criticality, AIS in its general use, with the corresponding message broadcasting protocol, is not secured from cyberattacks. Its security vulnerabilities have been extensively discussed in the literature, and several real incidents have been reported. To address the security vulnerabilities, several papers have been published proposing security solutions to AIS broadcasts. In this chapter, we categorise all these papers based on the compatibility of the solutions they describe with the AIS protocol standard, and we review all the proposed solutions providing insights on their applicability. We also discuss the main obstacles for their feasibility in practice and propose a possible way forward.