#!/bin/bash

build() {
    
    add_binary "ykchalresp"

    add_file "/usr/lib/yk2fe/yk2fe"
    add_file "/usr/bin/add_yk2fe"
    add_file "/usr/lib/udev/rules.d/69-yubikey.rules"
}

help() {
    cat <<HELPEOF
This hook collects a two-factor encryption passphrase using a Yubikey configured
for challenge-response as the second factor. This hook is intended to be used in
conjunction with the 'encrypt' hook with the 'cryptkeyscript' argument on the 
kernel command line pointing to '/usr/lib/yk2fe/yk2fe'.

cryptdevice=UUID=c87dcfc0-14a5-4afe-b4e9-bd81f952149c:encrypt-root 
cryptkeyscript=rootfs::/usr/lib/yk2fe/yk2fe

The encrypt hook will invoke the cryptkeyscript, which will block on user input.
The script will prompt for a first factor passphrase. After that is entered, the
script will use the first factor passphrase as a challenge to an attached 
Yubikey. The response of which will be passed to cryptsetup via the encrypt 
hook.

This hook assumes slot 2 of the Yubikey is configured for challenge-response, if
slot 1 is configured for challenge-response, enter -1 as the first factor 
passphrase. The script will then use slot 1 and will re-prompt for the first-
factor passphrase.

HELPEOF
}

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