Abstract: In the era of cloud computing, the large data owners are willing to store their precious data on cloud instead of their own server, to reduce maintenance burden and for low cost expenditure. This trend introduces the problem of data privacy for storing the sensitive data on cloud. Therefore, the confidential data has to be encrypted before outsourcing to cloud services. It is a challenging task to search an encrypted data because the relationship between plain text and encrypted text are concealed. We need an efficient search method for online retrieval of required data from the encrypted documents repository on cloud. We propose an efficient and secure search with hierarchical clustering method to improve the search efficiency and propose synonym search along with this method to increase the relevance of retrieved documents. This method ensures the Multi-keyword synonym search, relevance between documents, checks the ranking of documents and solves the problem of maintaining the relationship between plain text and encrypted text. It is proved with the help of practical analysis.
Keywords: Cloud Computing, Hierarchical clustering method, Multi-keyword synonym search.