Secure Data Sharing using Key Aggregation Cryptography: Secure sharing of multiple encrypted data between users of Cloud Storage using Java KeyStore concept

Secure Cloud Storage is an online platform for storing user data with sharing facilities among other users. The data is optionally encrypted before storing and decrypted on download by the system and the process is transparent to the end user. The platform also provides marking data private or public such that all public data are visible to end user and can perform search or download request to the owner. The data owner (user) can audit all such request and grant download access to individual or multiple files accordingly. Each file on the system is encrypted using different AES key and the real challenge come when multiple file needs to be shared between users. This constraint is addressed by applying a concept known as Key Aggregation which states the generation of constant size key for a single or multiple files and thereby end user can easily decrypt the shared files.