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Yubikey owner. You have to physically insert the USB key and then interact with it (touch it) to do signing/auth/etc. If you hijacked the signing touch step, yo

Yubikey owner. You have to physically insert the USB key and then interact with it (touch it) to do signing/auth/etc. If you hijacked the signing touch step, you'd notice that your signature wasn't generated by the touch and would know you're compromised. The key isn't plugged into the computer except when you're using it, and if you're in Qubes you have VM isolation for the USB ports. It narrows down the attack surface a lot, and makes anyone not using one a more attractive target.

gruez 7y ago
>Yubikey owner. You have to physically insert the USB key and then interact with it (touch it) to do signing/auth/etc. If you hijacked the signing touch step, you'd notice that your signature wasn't generated by the touch and would know you're compromised. as mentioned by a sibling comment this can be worked around by social engineering. some ideas: * simulating software/hardware/connection error, forcing the victim to retry. bonus points if you only start doing it after the victim installs an update to gpg * in cases where you know the signature doesn't have to be valid, substitute a legitimate signing request with your payload, and returning a fake signature for the legitimate request. for instance, the you coax the victim into sending a signed gpg email. you know that nobody would be checking the signature except for you, so you detect that case and use that opportunity to sign your payload, and return a fake signature to the email program. * my favorite: causing gpg to fail (thereby forcing the victim to retry) by injecting typos into his terminal when he's invoking gpg from the terminal