gpg decryption fails with no secret key error

Question

I have a gpg .key file that is used as passphrase for decrypting a .dat.pgp file. The encrypted .data.pgp file gets successfully decrypted on one server with same .key file

Answer 1

I got the same error when trying to decrypt the key from a different user account via su - . (Like jayhendren suggests in his answer)

In my case, this happened because there would normally start a graphical pinentry prompt so I could enter the password to decrypt the key, but the su -ed to user had no access to the (graphical) X-Window-System that was currently running.

The solution was to simply issue in that same console (as the user under which the X Server was currently running):

xhost +local:

Which gives other local users access to the currently running (local) X-Server. After that, the pinentry prompt appeared, I could enter the password to decrypt the key and it worked...

Of course you can also forward X over ssh connections. For this look into ssh's -X parameter (client side) and X11Forwarding yes (server side).