【ESP32/ NBIOT / AWS IOT】how to set three certification to connect aws iot with nbiot sim card?(using arduino IDE)

Question

This problem has been bothering me for a long time...

I'm using sim7020c and trying to connect aws iot with their three certifications, I have tried so many solutions which I searched from internet, but none of them work... I just can connect to net so far!

It would be very appreciated if anyone knows how to use nbiot sim card(any model can work in Taiwan) with ESP32 to connect AWS IOT(Especially, the part setting the three aws iot certifications)!

Thank you very much!

Answer 1

SIMCOM modules are quite picky on the root CA cert to be used.

Most browsers shows "Amazon Root CA 1" as the root CA, for example, for aws.amazon.com(You see this if you click on the padlock icon on the URL input field on any browser), however, this is not the top root CA. SIMCOM modules require top root CA (but it never clearly or explicitly documented in their lousy documentation). So if you try to load the "Amazon Root CA 1" cert as the root CA to the module, it will failed.

Here is the way I used to find out and get the top root CA. Run the following shell script to find out the cert chain up to 5 level.

openssl s_client -showcerts -verify 5 -connect aws.amazon.com:443 < /dev/null

This will shows a list of 4 certs, and noticed the last OU is Starfield Class 2 Certification Authority, and this is the top root CA of AWS.

  :
Certificate chain
 0 s:/CN=aws.amazon.com
   i:/C=US/O=Amazon/OU=Server CA 1B/CN=Amazon
-----BEGIN CERTIFICATE-----
  :
  :
-----END CERTIFICATE-----
 1 s:/C=US/O=Amazon/OU=Server CA 1B/CN=Amazon
   i:/C=US/O=Amazon/CN=Amazon Root CA 1
-----BEGIN CERTIFICATE-----
  :
  :
-----END CERTIFICATE-----
 2 s:/C=US/O=Amazon/CN=Amazon Root CA 1
   i:/C=US/ST=Arizona/L=Scottsdale/O=Starfield Technologies, Inc./CN=Starfield Services Root Certificate Authority - G2
-----BEGIN CERTIFICATE-----
  :
  :
-----END CERTIFICATE-----
 3 s:/C=US/ST=Arizona/L=Scottsdale/O=Starfield Technologies, Inc./CN=Starfield Services Root Certificate Authority - G2
   i:/C=US/O=Starfield Technologies, Inc./OU=Starfield Class 2 Certification Authority
-----BEGIN CERTIFICATE-----
  :
  :
-----END CERTIFICATE-----

I then use my computer to get the CA cert for the root CA. On both macOS and Linux machines, all the certs are stored in /etc/ssl, Linux stores each individual cert separates so you just need to find the file for Starfield Class 2 Certification Authority, macOS packs all the certs in one single certs.pem file, so you need to run a text editor and search for it.

Her is the root CA for Starfield Class 2 Certification Authority (you can verify it with openssl):

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

BTW, please make sure your SIMCOM module's RTC is set correctly or else it might failed in uploading or using the cert.