The sharing of high-quality information is essential for improving the user experience in distributed systems such as vehicular networks or IoT-based monitoring systems. Crowd-sourced data collection systems rely heavily on a secure and efficient consensus algorithm. However, consensus algorithms are often considered a bottleneck for scalability. With the emergence of blockchains, proof-of-work (PoW) has become the most popular and secure consensus algorithm for open and asynchronous distributed networks. However, PoW has been criticized for its energy consumption and waste of resources. To address this issue, alternative consensus protocols such as proof-of-stake (PoS) and proof-of-authority (PoA) have been proposed. Reputation-based consensus algorithms have recently gained attention but suffer from limitations in terms of privacy and predictability. In this paper, we propose a privacy-preserving proof-of-reputation (PoR) mechanism that combines ring signatures and dlog-based zero-knowledge proof systems. The proposed PoR algorithm aims to build unpredictable blockchain consensus algorithms that are privacy-friendly for permissioned blockchains. We describe the main algorithms used in PoR, demonstrate their security, and evaluate their performance through an experimental study. We conclude by discussing how these algorithms can be scaled to permissionless blockchain settings.