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I have created an offline MASTER key along with sub keys. The sub keys were sent to the Yubikey smartcard via the gpg 'keytocard'. The gpg --card-status command correctly identifies the information showing the masterkey id as well as the sub keys.
I want to use this via Windows. So I downloaded Gpg4win. It installed a GUI Kleopatra.
In Kleopatra I IMPORTED my PUBLIC key. However, I am unable to encrypt/sign anything as it states that I am required to import a private key. I'm a bit confused, isn't that the point of the Yubikey (NOT having the private key on a hard drive that is online)? Isn't the Yubikey THE PRIVATE KEY, again so that I don't have to have the private key on the hard drive?
I redid this all testing with another Yubikey and imported the private key (that was suppose to be offline) and it works, but it also decrypts WITHOUT REQUIRING THE YUBIKEY.
Ideally what I want to have happen is that it is a REQUIREMENT to have the Yubikey inserted into the machine to be able to encrypt or decrypt a file or clipboard.
I further note that this test one when I imported the private key it asks me for the passphrase rather than inserting the Yubikey. Once I imported the private key the Yubikey is all but worthless.
Any suggestions specific to gpg for Windows / Kleopatra GUI?