There is a site web for this project: http://rdiffopke.org/
You can follow the worklog instead of the commit messages in the worklog: http://rdiffopke.com/worklog

Project is just beginning, i have made algorithm and database schema, and just beginning to code now.

As i am a system admin, rdiffopke will be written in Perl.

rdiffopke is a reverse differential backup tool using offline private key encryption protocol

You can compare it to rdiff-backup, except that all files are encrypted, and rdiffopke never needs knowledge of private key to retrieve, compare and store files and increments.
The only time when the private key is needed is for interactive browsing of the stored files, and restoring.