Efficient update of encrypted files for cloud storage

We propose a method for file encryption based on AES-CTR suitable for cloud storage. Our method allows efficient updates of encrypted files by minimizing the amount of data that need to be re-encrypted. It achieves significantly better performance than full re-encryption for file updates. In addition our method addresses several security issues that traditional schemes used in the domain of disk encryption incur especially if used in the cloud. Efficient and secure update of encrypted files is relevant for applications using cloud storage or secure remote storage, which are becoming more and more common.