Systems and methods are disclosed for protecting user privacy in, for example, online advertising environments. The method includes receiving data related to a user in a first communication session between a host server and a client device, and generating a user profile associated with the user. The method further may include encrypting the user profile to produce encrypted user profile data and generating a decryption key for decrypting the encrypted user profile data. Thereafter, either the decryption key or a portion of the encrypted user profile data may be transmitted to the client device and then deleted from host server before ending the first communication session. The method further may include establishing a second communication session between the host server and the client device and retrieving the transmitted content. Then targeted advertising may be provided by decrypting the encrypted user profile data.