As the software technology evolves the focus of users are shifting form devices for data or information. This transformation requires reliable and scalable computing paradigms which satisfy the users processing and storage requirements. Service based, distributed, grid and web 2.0 are some of the most famous computing technologies. Conversions are occurring towards less managements and maintenance issues and despite of that the usage experience should be increased. But there are some security concerns like security, access control, privacy & isolation based trusted service delivery raises due to the data in an outsourced environment. Thus, several policies are created to define its boundaries. Also the type of user accessing the data and the service provided by the cloud needs to be verified. Thus the uses trust over the system can go down if the interoperability and security of services are satisfactory. To providing confidentiality to users data encryption is the traditional options which require decryption for reading or retrieving the data. But in outsourced environment the user is frequently accessing its data which may increase the overhead of performing such frequent encryption and then decryptions. Also for performing any operations the data need to be decrypted. It is something treating as a complex usage boundary. Thus, Homomorphic encryption is used to deal with such situations. This paper proposes a novel Third Party and Homomorphic Encryption (TPA-HE) based mechanism for secure computing. In this third party auditor and service provider is used for authentication and authorization of services & user profiles. It has three basic entities TPA, Cloud Service Provider, Encryption & Monitoring service to regularly analyze the security breaches in access & data transfer mechanism. To prove the effectiveness of suggested approach some of the results are taken which are better than the existing mechanism.