Abstract: A method for splitting a file in a computer device, the method comprising defining a moving window with a specified length and a random value; obtaining a content of the file by aligning the moving window to a specific place of the file; computing a result according to a cryptographic function of the content of the file; determining a cutting point according to the result and the random value; and splitting the file into segments according to the cutting point.

Abstract: A method for maintaining a single file in a shared storage is disclosed. The method comprises storing the single file and corresponding information into a virtual disk so that there is a direct mapping between each file byte and a byte in a sector of the virtual disk; encrypting the virtual disk according to a disk encryption algorithm; and uploading the encrypted virtual disk to the shared storage.

Abstract: A method for managing a file in a remote folder in a shared storage in a network system is disclosed. The method comprises generating a symmetric cryptographic key for the file; generating a ciphertext according to a symmetric encrypting function of the file operating with the symmetric cryptographic key for the file; generating a metadata according to the symmetric encrypting function of the symmetric cryptographic key for the file operating with a symmetric cryptographic key for the remote folder; and uploading the ciphertext and the metadata to the remote folder.