initrd_luks_pkcs/README.md

# initrd_luks_pkcs

## Acknowledgment
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.

## Single key setup

### General steps:
* 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

### details:
1. Install smartcard middleware

    ```sudo apt-get install pcscd opensc```

2. Erase smartcard

    ```pkcs15-init -E```
    
3. Initialize smartcard

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

    ```pkcs15-init -G rsa/2048 -i 01 -a 01 -u decrypt --pin 1234```
    
5. 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```
    
6. Export the public key from smartcard

    ```pkcs15-tool --read-public-key 01 -o public_key_rsa2048.pem```

7. 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```

8. 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```

9. Install the cryptsetup script and the initramfs-tool hook

    ```sudo cp lib/cryptsetup/scripts/decrypt_pkcs /lib/cryptsetup/script/ ```

    ```sudo cp etc/initramfs-tools/hooks/decrypt_pkcs /etc/initramfs-tools/hooks && sudo chmod +x /etc/initramfs-tools/hooks/decrypt_pkcs ```
    
    ```sudo cp etc/default/decrypt_pkcs /etc/default/ ```

    ```sudo update-initramfs -u```

10. Test smartcard (without USB Key)

11. Test LUKS Password (without Smartcard)

## Multi keys setup

The setup is quite the same except that you need to put all the key files in the expected format. 
With the provided exemple config and script all keys must be stored in the `/etc/keys` folder with the following filename : `internal-${ENCODED_SERIAL}.enc` with `${ENCODED_SERIAL} the result of the following commands : 

```
pkcs15-tool -c 2>/dev/null  | awk '{ if ($1$2=="Encodedserial") {print $NF}}'
```

You need to modify the `/etc/default/decrypt_pkcs` and set `DECIPHER_MULTI` to `1`

and copy the script in charge of selecting the right key file form initramfs : 

    ```sudo mkdir -p /usr/share/decrypt_pkcs && sudo cp usr/share/decrypt_pkcs/pkcs15_get-key.sh /usr/share/decrypt_pkcs/ && sudo chmod +x /usr/share/decrypt_pkcs/pkcs15_get-key.sh ```

Every time a new key is added, the initrd mus be regenerated : 

    ```sudo update-initramfs -u```