ssl_publy

Arduino Failure to Connect to GCP discussion

I have a problem with connecting to GCP with MQTT/SSL. I tried to privately debug this problem, then I filed some issues, then I started this discussion.

The files here are a mix of notes in markdown, source/project directories and screenshots.

So what's the problem?

LOL, when I first started this endeavor the problem was connecting to GCP. Now the problem is to understand why. Although, I can connect to google.com using HTTPS, I can't when using MQTT/SSL.

I didn't just come up with the original source/firmware. I am using two samples publicly available github repo's. One is from Arduino and the other is from Google.

• GoogleCloudPlatform/google-cloud-iot-arduinio
• Arduino/ArduinoCloudProviderExamples

So what is the difference?

• Arduino
  • Stores private key in crypto chip
  • Signs JWT with crypto chip
• GCP
  • Stores private key in source
  • Performs crypto routines in software

For simplicity sake I will focus on the Arduino, since it has the advantage of using the crypto chip - storage of private key, crypto routines in hardware.

Guide to these notes

For the most part these are unedited. Newer documents build on earlier knowledge. With that in mind, here is a suggested table of contents:

• First attempt with Wireshark crash_dump.md
• Uncategorized notes notes.md
• Important URLs urls.md
• Big picture big_picture.md
• Arduino example notes arduino.md
• GCP example notes gcp.md

I should compare the output of these two commands:

• openssl s_client -connect mqtt.2030.ltsapis.goog:8883
• openssl s_client -connect mqtt.googleapis.com:8883

other commands too use openssl s_client -showcerts -connect www.google.com:443 | less

echo | openssl s_client -showcerts -servername gnupg.org -connect gnupg.org:443 2>/dev/null | openssl x509 -inform pem -noout -text

curl --insecure -vvI https://www.google.com 2>&1 | awk 'BEGIN { cert=0 } /^* SSL connection/ { cert=1 } /^*/ { if (cert) print }'

nmap -p 443 --script ssl-cert gnupg.org