Using Outlook 2013 64bit on Windows 7 64bit, I have setup GnuPG which allows me to send encrypted emails. To do that, I asked someone for their public key. I sent them an email and cc'ed in another person. The original recipient (the person who sent me their public key) was able to decrypt the message, and the cc'ed person was not able to decrypt the message (as the cc'ed person did not have the private key to match the public key I used to send the email). All good so far.
I installed k9mail on my phone (Android 8.1.1), I tried importing the same persons public key, I selected that person to send an email to them, and when I clicked send, I get a message saying
no key configured for this account, check your settings.
I check the key settings for the public key I was sent, and it says
Any idea why the public key I received works from Outlook 2013, but not from Android's k9mail?
I've received an email with an attachment:
-----BEGIN PGP SIGNATURE----- long string goes here -----END PGP SIGNATURE-----
How do I use this signature to check that the email is truly from the person I assume to have sent it?
I am looking for a Windows/Linux command line method to verify the email.