Abstract: To ensure the security of data interaction between users and servers, an ultra-lightweight identity authentication protocol is proposed in this paper to ensure the security of important privacy data for users. The protocol adopted words synthesis operation to encrypt the transmitted private data. This operation comprehensively utilized the Hamming weights possessed by the private data itself to determine the size relationship, and used this as the result to perform different methods of addition, subtraction, remainder, and synthesis operations to obtain the results. From multiple perspectives, protocol analysis shows that the protocol not only can resist various types of attacks, but also has better computational complexity compared to identity authentication protocols.