Why is OpenSSL able to use a key file my user shouldn't have access to?
The following command works even though I really don't think I should have permission to the key file: $ openssl aes-256-cbc -d -pbkdf2 -in etc_backup.tar.xz.enc -out etc_backup.tar.xz -k /etc/ssl/private/etcBackup.key
I'm unable to even ascertain the existence of the key file under my normal user. I'm a member of only two groups, my own group and vboxusers.
Just to verify all permission-related things in one go, see if you can open the key as your user with an editor like vi or nano. This will let you separate out some behavior specific to OpenSSL vs some behavior purely permissions-based.
I’m not sure what’s happening here, but the above test can at least narrow the focus.