gcp.md

Google Example Notes

20210821

1. cloned the github repo here. added to .gitignore
2. ran install.sh script to see what it did. It seems it is installing software
3. noticed its taking a while to install.
4. Now its using python. whew lad I hope its using the correct python.
5. completed
6. changed to ~/progs/ssl_publy/google-cloud-iot-arduino/examples/MKR1000-lwmqtt
7. Copied this example to ~/progs/ssl_publy/gcp-example/
8. Copied arduino secrets file and makefile from aruduino example to here
9. Tested with make and it compiles.

Second attempt at the project repo readme instructions

Notes on Firmware and GCP keys

Creating the Device Key

From the GoogleCloudPlatform/google-cloud-iot-arduino

Generate a EC256 key - eliptical curve

cd keys/
openssl ecparam -genkey -name prime256v1 -noout -out ec_private.pem
openssl ec -in ec_private.pem -pubout -out ec_public.pem

Results in two files:

• ec_private.pem
• ec_public.pem

GCP usage of public key to identify the arduino

This creates a device in the IoT Core Registry. The command uses the public key created above.

gcloud iot devices create atest-dev  --region=us-central1 \
    --registry=atest-registry \
    --public-key path=ec_public.pem,type=es256

Arduino usage of public/private key in software

Do this to get data for private key entry in arduino code

cd keys/
openssl ec -in ec_private.pem -noout -text

Result looks like this:

read EC key
Private-Key: (256 bit)
priv:
    XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:
    XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:
    XX:XX
pub:
    XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:
    XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:
    XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:
    XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:
    XX:XX:XX:XX:XX
ASN1 OID: prime256v1
NIST CURVE: P-256

The GCP example mentions the cert urls. The cloud.google.com/docs on IoT core refer to pki.goog/root.crt (or whatever the url is) as the site for the certs. I used the firmware updater to load the ip address from nslookup on pki.goog and perhaps it loaded them or perhaps not.

Still the error persists.

This site has this code arduino-libraries/WiFi101#217

static sint8 burn_certificates(void)
{
	sint8	ret = 0;

	printf(">> De-init WINC device to enter into download mode\r\n");
	m2m_wifi_deinit(NULL);

    if(0 != m2m_wifi_download_mode()) {
		printf("Unable to initialize bus, Press RESET button to try again.\r\n");
		while(1);
	}

	printf(">> WINC entered into download mode\r\n");

	printf("---> Start Certificate Upload on WINC\r\n");

	for (uint8 idx=0; idx < NUM_OF_ROOT_TLS_CHAIN_CERTIFICATES; idx++)
	{
	   /* Write the Root certificates to WINC */
	   if(root_tls_certs_name[idx].cert_type == ROOT_CERT)
	     ret += WriteRootCertificate(root_tls_certs[idx].pu8FileData,root_tls_certs[idx].u32FileSz);

	   /* Write the TLS RSA based certificates to WINC */
       if(root_tls_certs_name[idx].cert_type == TLS_RSA_CERT)
	   {
       	 ret += WriteTlsCertificate(root_tls_certs[idx].pu8FileData,root_tls_certs[idx].u32FileSz,
		 &root_tls_certs[idx+1],root_tls_certs_name[idx].numOfChainCert);
		 idx = idx + root_tls_certs_name[idx].numOfChainCert;
	   }

	   /* Write the TLS ECC based certificates to WINC */
       if(root_tls_certs_name[idx].cert_type == TLS_ECC_CERT)
       {
	       ret += WriteTlsCertificate(NULL,0,&root_tls_certs[idx],root_tls_certs_name[idx].numOfChainCert);
		   idx = idx + root_tls_certs_name[idx].numOfChainCert -1;
       }
    }

	return ret;
}