With cloud services, the user’s data is synchronized automatically without requiring the devices to be connected together, just connect to the Internet is enough. However, the problem needs to be resolved is the security of data in the service.
Data synchronization and security issues: The cloud computing service that allows storage and sync files online is widely used today as Google Drive, Microsoft SkyDrive, Dropbox and Apple iCloud… In particular, the new Google Drive officially put into operation at the end of April 2012, and iCloud, it’s only supported for Mac and iOS platforms.
With cloud computing services, when users need to synchronize files between different devices, you must configure each device to a software service provider, and determine a folder for the file to sync . The change in the user’s directory (add / delete files, edit files) will be automatically executed on all related equipment. Thus, users do not need to copy files to portable use elsewhere; not update the file on any device and not have to think about “the latest version of the document is stored on the device.” On the transmission line (the synchronization is done via HTTPS protocol) and no service provider of the above commitment to ensure confidentiality of user data when stored in the cloud. Even Google also requires the use of user data for their purposes. So, to get the benefits that these services bring and want to ensure the confidentiality of their data, users need to use encryption. Data needs to be encrypted on the client (on the user’s device) and transmitted to the server in an encrypted format.
Among the service cloud computing enables data synchronization between a user’s device, it seems more popular DropBox. According to statistics, every 5 minutes, the users of DropBox storage perform about a million files. There are about 25 million people are using this service. Therefore, we will consider data encryption when using Dropbox. The service applies to the other is done similarly. The addition of encryption for Dropbox story is not only that there BoxCryptor and EncFS SecretSync. SecretSync encrypt data using AES- 256 and supports three operating systems are Windows, Mac OS X and Linux. If Dropbox not meet security requirements, so it would be logical if we want to find another service instead. The candidates may be Wuala. To authenticate, Wuala uses RSA- 2048, also to encrypt data, using AES- 128.