I am trying to sign TWRP (Redmi Note 8 ginkgo) using GPG on Windows 10. I have imported the TWRP public key, however, when I select the file for signing, it does not show up in the drop-down menu in Kleopatra. From my research, this seems to be due to it being a public key and missing the private key part (correct me if this is wrong please).
I have no idea how to acquire such a key that would allow me to sign TWRP correctly. Could anyone please help me with this?
Additional info:
The bootloader is locked and I don't have TWRP installed. I want to use the command fastboot boot twrp.img, however, it doesn't work with a locked bootloader. I get the error FAILED (remote: Fastboot boot command is not available in locked device). I read somewhere that it might work if TWRP was signed without having to unlock the bootloader.
Thank you! :)