The Automatic Identification System (AIS) is critical in maritime operations, military, law enforcement, and other fields. However, its security has been weak, particularly in terms of authentication. Despite efforts to improve AIS security, a standard has not yet been established. This paper assesses the current state of research and proposes an authentication scheme that uses certificateless cryptography compatible with standard AIS versions. Simulations and theoretical analysis demonstrate that this proposed scheme provides strong security guarantees and efficient performance, making it a promising candidate for authenticating AIS signals.