Public Key is not listed for Selection for Encryption

I have just installed gpg4win 3.1.5 and this is my first time working with it. I have created the keypair and exported the public key to an old unix box and have been able to encrypt a file on the unix box and decrypt it on the gpg4win server. I have exported the public key from the unix box and imported it into Kleopatra. But when I right click on a file to encrypt, the key for the unix box is not listed in the “Encrypt for others” box. I type in the email address but there is no drop down to select from, and the icon on the left changes to a white X in a red square. I assume that this means it doesn’t match.

The unix server has GPG 1.4.7. Is there an incompatibility issue? If not, what am I doing wrong?

I have attached a shot showing the new key and imported key in Kleopatra, as well as the encrypt files window showing the lack of a match for the email address.


Dear Paul,

(sorry for the late answer, I must have missed your post last time I was looking.)

it is possible that very old keys stop working because they are using algorithms or settings that are not considered sufficiently “safe” anymore.

Try to encrypt to the key on the command line (see the corresponding section on probably something like

gpg -v -e -r YOURKEY somefile.txt

and you’ll probably see more diagnostic messages that may explain your situation.

Best Regards,

Thank you Bernhard,
You answer is expected and appreciated. And I am sorry for getting sidetracked and not finding your response in my email until today. I had suspected it would be something like that and you have answered my question.


you are welcome!

Were you able to diagnose your situation for good?