In healthcare industry, clinical decision support system plays an important role. As the clinical data is confidential data, there is a huge requirement of a secure data security system which can maintain secrecy of data. In this paper, we propose a homomorphic encryption technique which is able to perform the different operations on data by preserving the privacy of data. As, the data privacy is the primary concern. All the operations are performed on the encrypted data. An innovated homomorphic encryption algorithm which supports large integer, small integer as well as text data encryption will be designed. We will perform operations on encrypted data rather than decrypting it during processing. As our proposed algorithm includes large integer as well as text data, our system will be more efficient than existing system.