Update: the above seems to be a known bug:

duplicity - Bugs: bug #19998, Incremental Backups Do Not Work On…
https://savannah.nongnu.org/bugs/index.php?19998

“This is caused by a ValueError exception in duplicity’s tarfile.py, because it uses int() on strings containing (NUL) characters.
This exception does not happen with Python 2.4, and also is not specific to Ubuntu’s Python 2.5.”

Don’t have Python 2.4 now, so cannot tell..

Then, I needed to understand there are two different sets of keys - one for ssh/scp (which should work passwordless before tryig duplicity), and another - gpg - for encrypting the archives. I also encountered the gpg problem, solved it by installing gnupg, running
$ gpg –gen-key
here noting the comment ‘gpg: key ABABABAB marked as ultimately trusted’
and then running
$ gpg –list-keys
you will see:
.. ————————————–
.. pub 1024D/ABABABAB 2008-10-12
.. uid XX

and then use this ABABABAB key as in

$ duplicity -–encrypt-key ABABABAB -–sign-key ABABABAB “/cygdrive/c/TEMP” scp://user@server.net/bckp

Now, this is all OK - but I have a problem - this does create an archive on the server, but if I execute the exact same command several times in a row without changing files, it always uploads archives with sizes the same as initial one !! Shouldn’t it detect no changes, and transfer 0 bytes?: “If the above is run repeatedly, the first will be a full backup, and subsequent ones will be incremental.” http://duplicity.nongnu.org/duplicity.1.html. Same thing happens for specifying –no-encryption instead of encryption and signing keys. (I n00bishly suspect this may have to do something with the Cygwin filesystem…)

Any pointers for this would be great!

Update2: tried http://launchpadlibrarian.net/7933525/duplicity_0.4.2-10.1ubuntu1.1.dsc.diff manually, ran setup.py again, but there seems to be no fix - it still cannot detect increments, not even when trying without encryption, and running:

$ duplicity –verify –no-encryption -v 9 scp://user@server.net/bckp /cygdrive/c/temp/

I don’t believe the patches are required now, but haven’t done extensive tests yet.

In cygwin install, need to select following packages in addition to defaults:
gcc-core
gnupg
librsync-devel
ncftp
openssh
openssl
wget (to simplify installing the non-cygwin packages)

I couldn’t find python-dev anymore, but it didn’t seem to matter.

I had to download the following packages separately as they are not bundled as a cygwin package:
GnuPGInterface 0.3.2 or later (http://py-gnupg.sourceforge.net)
Boto 0.9d or later (http://code.google.com/p/boto) — if you wish to use the Amazon S3 service)
pexpect 2.1 or later (http://pexpect.sourceforge.net) — if you plan to use the ssh backend

For some reason I’m getting the “mkpasswd (272): [1359] An internal error occurred.” message from my cygwin install and can’t find a good fix yet, but everything seems to work ok so far.

Broken pipe occurs - at least with me - when using a key wit dsa over 1024 (e.g. 2048 default running ubuntu/debian).

Create a new key using lower strength!

I’m using the same key for signing encrypting and if I’m using “plain GPG” it works perfectly.

I execute
TMPDIR=”/tmp” PASSPHRASE=”XXX” nice -n 19 /usr/bin/duplicity –short-filenames –encrypt-key XXX –sign-key XXX –include /etc/ –exclude ‘**’ / file:///var/backups/

This is what I get:
No signatures found, switching to full backup.
Traceback (most recent call last):
File “/usr/bin/duplicity”, line 373, in ?
if __name__ == “__main__”: main()
File “/usr/bin/duplicity”, line 366, in main
if not sig_chain: full_backup(col_stats)
File “/usr/bin/duplicity”, line 142, in full_backup
bytes_written = write_multivol(”full”, tarblock_iter, globals.backend)
File “/usr/bin/duplicity”, line 78, in write_multivol
globals.gpg_profile)
File “/usr/lib/python2.4/site-packages/duplicity/gpg.py”, line 215, in GPGWrit
eFile
to_gpg_fp.write(data)
IOError: [Errno 32] Broken pipe
close failed: [Errno 32] Broken pipe

Do you have any idea?

Thanks,
Mike