initrd_luks_pkcs/README.md

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2021-04-04 17:51:53 +00:00
# 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.
### The 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
### The 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 decrypt_pkcs /lib/cryptsetup/script/ ```
```sudo cp decrypt_pkcs_hook /etc/initramfs-tools/hooks && chmod +x /etc/initramfs-tools/hooks/decrypt_pkcs_hook ```
```sudo cp decrypt_pkcs_default /etc/default/decrypt_pkcs ```
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```sudo update-initramfs -u```
10. Test smartcard (without USB Key)
11. Test LUKS Password (without Smartcard)