Each day newer security and privacy risks are emerging in the online world. Users are often wary of using online services because they are not entirely confident of the level of security the provider is offering, particularly when such services may involve monetary transactions. Often the level of security in the algorithms underlying online and cloud-based services cannot be controlled by the user but is decided by the service provider. We propose a cloud-based Privacy Aware Preference Aggregation Service (PAPAS) that enables users to match preferences with other interested users of the service to find partners for negotiation, peer-groups with similar interests etc while also allowing users the ability to decide the level of security desired from the service, especially with respect to correct output and privacy of inputs of the protocol. It also lets users express their level of trust on the provider enabling or disabling it to act as a mediating agent in the protocols. Along with this we analyze the security of a preference hiding algorithm in the literature based on the security levels we propose for the PAPAS framework and suggest an improved version of the multi-party privacy preserving preference aggregation algorithm that does not require a mediating agent.