Patent attributes
Data chunks encrypted using an encryption key are backed up to a server. Each chunk is associated with plain and encryption signatures. The plain signature is based on an unencrypted version of a chunk. The encryption signature is based on an encrypted version of the chunk. A new data chunk is identified and a new plain signature for the new chunk is calculated. A request is made for a current key and the new chunk is encrypted using the current key to obtain a new encryption signature. The new encryption and plain signatures are sent to the server for comparison against the existing encryption and plain signatures. If the new encryption signature does not match an encryption signature of an existing chunk and the new plain signature matches a plain signature of the existing chunk, the new chunk is transmitted to the server to replace the existing chunk.
