A Cryptographic Solution to the Predefind Bound of Ciphertext Classes in KAC

Abstract

In Cloud Computingsecure data sharing is an important functionality. Cloud computing is the storing of data online which is accessible from multiple and connected resources. It is the fastest growing field in computer world which serves various services to users. Using Cloud Storage, users can remotely store their data and enjoy the on-demand high quality applications and services. This paper attempts to show how data is shared among cloud users securely, efficiently, and flexibly. On cloud anyone can share data as much they want to i.e. only selected content can be shared. With cryptography users can share the data to others in safe way. So that user encrypts data and upload it on cloud server. The proposed algorithm uses a new cryptosystem that is called as Key Aggregate Cryptosystem (KAC)[1] which generates a single key for multiple files. In particular, it uses a public key encryption which releases aggregate key for set of secret keys. With this aggregate key others can decrypt ciphertext set and remaining encrypted files outside the set are remains confidential.