Syncing only after checking against stored checksum?

[Johannes Graumann]

Hi,

I have remote storage for my family's image collection, which I sync to 
using rsync.
I wonder now what happens if on my local drive a small number of sectors get 
corrupted. Rsync (if using the "-c" option) will figure the local file was 
changed and transfer that (faulty) change to the remote side.
I'd love to do something like this:
1. Checksum all files and store them (file).
2. Note down checksum of checksum db from 1.
3. Sync everything (including checksum db from 1.) to remote.
4. Upon new sync make sure that
	- remote and local checksum db are identical (if not decide on noted 	
		checksum which one to take)
	- new files are transfered to remote
	- local files not matching their stored checksum are (upon asking the user) 
		either transfered to remote (if willingly changed) or restored from remote
	- update checksum db and sync it

Is something like this already implemented? I know unison and it might do 
the trick, but I can't have it installed remotely ...

Thanks for any input, Joh