[Duplicity-talk] Unnecessarily asking for passphrase on incremental backup

[Georg Lutz]

Hi,

I currently experience that in some situations duplicity is asking for
GnuPG passphrase when I think it shouldn't necessarily.

Background: I would like to run my duplicity backup script completely
unattended without any user interaction. This means also that I cannot
enter a password for my GPG keys. Therefore I also use different keys for
encryption and signing. The encryption key is my regular GPG. Thanks to
asymetric encryption I do not need to enter the passphrase when encrypting
with my public key. For signing I created a special signing only key pair
without a passphrase.

My backup script consists basically out of the following lines:

duplicity \
--archive-dir /cygdrive/f/backups/duplicity/archive \
--log-file /cygdrive/d/temp/duplicity_log.txt \
--volsize 2000 --encrypt-key 9E94B21D --sign-key 275ADCCB \
--verbosity debug \
   --include '/cygdrive/d/temp/test.txt' \
   --exclude '**' \
   '/cygdrive' \
   file:///cygdrive/f/backups/duplicity/data


The first (full) backup runs without problems if I enter an empty passphrase
when being asked. In fact there is a "export PASSPHRASE=notneeded" before
those lines.

The second time duplicity detects the previous full backup and triggers a
incremental backup. And now duplicity asks for the passphrase to my
encryption key.

Why does this happen? Of course in the data store (duplicity/data) the
files are all encrypted. But shouldn't it use the unencrypted version in
duplicity/archive when its available?

I have attached the logfiles for both the full and the incremental run.


Regards
   Georg

duplicity_log.zip
Description: Zip archive