Feature Request for Reverse Mode: Content-Defined Chunking #192

Modern backup systems like restic and kopia use content-defined chunking to avoid taking the performance hit described in the documentation for cppcryptfs as follows:

Also, if your backup utility supports delta-syncing (as rsync does) when working with the unencrypted data, then it will also do delta-syncing with the encrypted data in reverse mode as long as the data is changed in-place. However, if data is inserted into a file, then a cascading change will appear in the encrypted file data from the point at which the data was inserted (actually, starting with that whole encryption block) and the data from there on will need to be copied again.

Several github repositories provide implementations of this concept:

Restic

Other implemenations