On root directory of your rom, run:
git clone https://github.com/isg32/sign_scripts.git scripts
chmod +x scripts/generate_certs.sh
./scripts/generate_certs.sh
You will need to the leave the passphrase blank and press Enter to generate keys without password.
It will display something like this:
Enter password for '/home/sapan/.android-certs/bluetooth' (blank for none; password will be visible):
On root directory of your rom, run:
git clone https://github.com/isg32/sign_scripts.git scripts
chmod +x scripts/build_and_sign.sh
./scripts/build_and_sign.sh