Recently, data storage and processing have demand highly, which has increased in large data era. The major concerns of business users and organisation perspective are the Data confidentiality, availability and integrity while outsourcing the data in cloud. There are still exists some security attacks while storing the data even various techniques are implemented to solve these issues. In this research, we mainly focuses on security threats while storing data, especially confidential data which has classified from the unstructured data by using TDF algorithm (Training Data Set filtering) based on k-nearest neighbor algorithm. Finally, confidential data encrypted with Elliptic Curve Cryptography and securely stored in cloud. We can assure Data Security with the help of using Data Classification with encryption technique. Experiment analysis shows to get efficient results and which ensures the secrecy and privacy to the user data. © 2018 American Scientific Publishers All rights reserved.