[GnuPG-users] identical files -> non-identical encrypted files

[Kiss Gabor (Bitman)]

> Ian> I have a local file that I want to encrypt and upload to a remote
> Ian> machine in encrypted form.  Encrypting is farily quick, but
> Ian> uploading is slow, so I use rsync for the other (unencrypted)
> Ian> files.  But the fact that the encrypted file is different each time
> Ian> defeats the rsync incremental upload.
> 
> Gabor> Jari Ruusu's loop-aes uses the following method: - it encrypts
> Gabor> disk/file with AES - it has 1-65 pieces of 128-256 bit keys for
> Gabor> this symmetric cipher - disk keys are stored in a file that is
> Gabor> encrypted by GPG - Several users may have access to this file
> Gabor> (each with his own secret key)
> 
> Ok, but how does that solve my problem?  Even if I encrypt my file with
> a symmetric cipher I face the same issue - each encrypted copy will be
> different.

The password is not random therefore every time you
encrypt the same plaintext you got the same cryptfile.
(The opposite would cause big problems in a disk encryption system. :-)
Then this password is encrypted and stored transparently in a .gpg file.
Why don't you try it?

Gabor