The average costs of data leakage are steadily on the rise. As a consequence, several data security and access control mechanisms have been introduced, ranging from data encryption to intrusion detection or role-based access control, doing a great work in protecting sensitive information. However, the majority of these concepts are centrally controlled by administrators, who are one of the major threats to corporate security. This work presents a security protocol for data privacy that is strictly controlled by the data owner. Therefore, we integrate pseudonymization and encryption techniques to create a methodology that uses pseudonyms as access control mechanism, protects secret cryptographic keys by a layer-based security model, and provides privacypreserving querying.