Kavitha K, Manjula R
Abstract: Cryptography in the field of information technology is an art to protect data privacy using standard mathematical techniques. Cloud computing, one of the emerging techniques to lease computing resources on demand, makes use of remote data storage where data owner does not possess direct control over her data. To protect privacy of users data and to enable user to verify integrity of the data stored on remote location, modern cryptographic techniques are used. So, if users paying awareness in selection of proper cryptographic scheme then it can achieve confidentiality without losing performance of Cloud. For Achieving high performance and security users can select any of modern encryption techniques. Here considering time and key difference to compare which algorithm is best in security and speed over the data. Data sharing being important functionality in cloud storage implements how to securely, efficiently, and flexibly share data with others. The public-key cryptosystems produce constant-size cipher texts that efficiently delegate the decryption rights for any set of cipher texts. The importance is that one can aggregate any set of secret keys and make them as compact as a single key, but encompassing the power of all the keys being aggregated. The secret key holder can release a constant-size aggregate key for flexible choices of cipher text set in cloud storage, but the other encrypted files outside the set remain confidential. The aggregate key can be conveniently sent to others or be stored in a smart card with very limited secure storage.
Keywords: outsourced data, share data, authentication, Cryptography, data owner, encrypts data and Key aggregate cryptosystem KAC