<p>With the rapid development of new network technologies, such as cloud computing, server-side trustworthiness has diminished, and user privacy issues have emerged as a major obstacle to the further advancement of modern information services. In this paper, we propose an edge computing architecture that replaces the identity associated with each user information service request with an identity from another user on the edge side. This breaks the association between users and their requests, thus protecting user information service privacy. First, we propose a basic framework that combines edge computing and identity replacement to protect user information service privacy. This framework ensures that information services maintain their accuracy, efficiency and generality, without requiring changes to the service algorithms or user habits, thereby demonstrating strong practicality. Second, we define an identity-replacement-based model to protect user information service privacy. This model formulates the privacy constraints and cost constraints that should be satisfied in the process of user identity replacement on the edge side. Third, according to four matching strategies proposed based on the privacy model, we present an implementation algorithm for the privacy model. Finally, both theoretical analysis and experimental evaluation demonstrate the effectiveness of the proposed approach. That is, compared with existing technical methods, it has better overall performance in terms of accuracy, efficiency, generality and practicability. This approach can improve the security of user information service privacy on the untrusted cloud side without compromising the usability of information services.</p>