Intelligent transportation system (ITS) has gained popularity in recent times because it has the prospect to improve traffic efficiency, minimize traffic accident, provide convenience, and reduce air pollution. In this paper, we propose a secure, autonomous, anonymous, and privacy‐preserving traffic movement analysis scheme for ITS. In the proposed scheme, fine‐grained traffic information such as average speed can be obtained without compromising users' privacy. We employ modified Paillier cryptosystem and Chinese Remainder Theorem to aggregate data of heterogeneous roads for saving bandwidth and Boneh short signature for authentication. The proposed scheme is autonomous by allowing users to generate their private/public key pair on their own for communication. In addition, we show that the proposed scheme meets all the security and privacy requirements of ITS such as data confidentiality and integrity, anonymous authentication, conditional traceability, and attack resistance. The performance analysis shows that the proposed scheme is very efficient.