Nowadays very difficult to store the data in secure manner. Most of the internet users suffer from security problems. To store the data in the cloud is easy task but the major issue here security .In cloud lot of is redundant data present so most of the space filled with replicated information it also a major challenge. Previous papers are described about deduplication with low security algorithms. Example symmetric algorithms are used to provide security. IN this paper we proposed high security public-key algorithms and for authentication purpose we extend various algorithms. Finally we protect the cloud from unauthorized access and also eliminate the replicated data using deduplication technique.