luks_pkcs

It has been tested on a debian laptop and a mobian pinephone. The smartcard generation come from inspired by https://github.com/swoopla/smartcard-luks . The OSK-SDL parts are inspired by Mobian package https://salsa.debian.org/DebianOnMobile-team/osk-sdl.

Erase and initialize card
Create public/private key pair on smartcard
Create key file and add it to a LUKS key slot
Encrypt key file using public key from smartcard
Modify initramfs to use smartcard to decrypt the encrypted keyfile
Modify decrypt_opensc script to swicth between smartcard and luks password and add osk-sdl support for touchscreen device

Install smartcard middleware

sudo apt-get install pcscd opensc
Erase smartcard

pkcs15-init -E
Initialize smartcard

pkcs15-init --create-pkcs15 -p pkcs15+onepin --pin 1234 --puk 4321
Create public/private key pair on smartcard

pkcs15-init -G rsa/2048 -i 01 -a 01 -u decrypt --pin 1234
Create a random key file and add it to a LUKS key slot

sudo touch /root/rootkey

sudo chmod 600 /root/rootkey

sudo dd if=/dev/random of=/root/rootkey bs=1 count=245 #change to urandom if you can't wait

sudo cryptsetup luksAddKey /dev/sda2 /root/rootkey
Export the public key from smartcard

pkcs15-tool --read-public-key 01 -o public_key_rsa2048.pem
Encrypt key file using public key

sudo openssl rsautl -encrypt -pubin -inkey public_key_rsa2048.pem -in /root/rootkey -out /root/rootkey.enc

sudo rm /root/rootkey
Edit crypttab. This change sends the encrypted key file as a param to the keyscript

This should be of the form:

mapped_device_name source_block_device key_file luks,keyscript=decrypt_pkcs

For example:

sda2_crypt UUID=d332ecc5-ce8b-4900-a04a-a79abd029d6d /root/rootkey.enc luks,keyscript=decrypt_pkcs
Install the cryptsetup script and the initramfs-tool hook

sudo cp decrypt_pkcs /lib/cryptsetup/script/

sudo cp decrypt_pkcs_hook /etc/initramfs-tools/hooks && chmod +x /etc/initramfs-tools/hooks/decrypt_pkcs_hook

sudo update-initramfs -u
Test smartcard (without USB Key)
Test LUKS Password (without Smartcard)