Scripts for provisioning devices for Google Cloud IoT Core

These scripts will be run on one of two machines. Each step below notes where it should be run.

• workstation: Your development machine.
• device: The device you're provisioning so that it can talk to Cloud IoT Core.

1. [run on workstation] Use make_ca.sh to set up a certificate authority. It will be used to sign devices' certs. When you set up the registry on Cloud IoT Core, supply the CA cert. This is done only once.
2. [run on device] Run make_device_key_and_csr.sh on the device that you are provisioning. This is important! You should not generate a private key on some other machine (e.g. workstation) and then scp it to the device. The private key should only ever exist on the device. This will make a .pem file (the private key) and a .csr file (the certificate signing request). NOTE: The device ID you provide here MUST be the same as the device ID you enter in the Cloud IoT Core registry.
3. [run on workstation] scp the certificate signing request (the .csr file) to your workstation. Use sign_csr.sh to sign it. The cert will be placed alongside the original .csr file, and it will have the extension .x509. When you add the device to the Cloud IoT core registry, supply the cert. You can also scp the cert back to the device if you like.