Nowadays, cloud data outsourcing provides users and companies with powerful capabilities to store and process their data in third-party data centers. However, when a user stores her sensitive data in a public cloud, they becomes vulnerable to several attacks, e.g., from the employees of the cloud provider. One solution for protecting the user data against attacks is to encrypt the data before sending them to the cloud servers. Then, the challenge is to answer user queries over encrypted data. In this paper, we present a summary of our initial results in processing top-k k queries on encrypted data.