Using the Computado Rita as a ESP32 development environment

Goal

To have the IoT device GET and POST a URL to a HTTPS web server over WiFi.

Need to do;

Create a PKI certificate authority and server certificate
Create a WiFi Access Point (AP) (Hotspot)
Install and configure nginx web server and time server
Install esp-idf, a ESP32 deveopment system
Clone the IoT code respository
Setup ESP32 to connect to Wifi
Setup ESP32 to connect to https server

Equipment

Computado Rita as server ; RAM 4G or 8G
Seeed Xiao ESP32C3 or just change the configurations other ESP32 devices,
USB-A to USB-C cable

Setup Access Point (hotspot)*

Create the hotspot using NetworkManager

$ sudo nmtui

Force NetworkManager to use WPA2 by editing

/etc/NetworkManager/system_connections/connection 1.nmconnection

Add the WPA2 protocol to wifi-security proto=rsn

Install nginx web server, time servere and other debug tools

$ sudo install nginx nginx-extras rsyslog git ntp ntp-date ntpsec wireshark

Create PKI root certificate and server certificate

Create directory /etc/nginx/crypto and in it;

Create a self signed root certificate and unencrypted key.

$ openssl req -x509 -sha256 -days 1825 -noenc -newkey rsa:2048 -keyout rootCA.key -out rootCA.crt

Create Certificate Signing Request ( CSR ) for the host domain

$ openssl req -newkey rsa:2048 -noenc -keyout domain.key -out domain.csr

Sign the CSR with the root CA

$ openssl x509 -req -CA rootCA.crt -CAkey rootCA.key -in domain.csr -out domain.crt -days 365 -CAcreateserial

Setup SSL on nginx

In /etc/nginx/sites-enabled/default, Uncomment “listen 443” lines and change snakeoil.conf to ssl.conf

Create a file in /etc/nginx/snippets/ssl.conf with

ssl_certificate /etc/nginx/crypto/domain.crt;
ssl_certificate_key /etc/nginx/crypto/domain.key

Restart nginx

Add echo location in /etc/nginx/sites-enables/default for POST request

location /echo {
    echo_read_request_body:
    echo_request_body;
    default_type application/json;
    chunked_transfer_encoding off;
}  

Restart nginx

Install esp-idf

Install esp-idf

Clone IoTCRHTTPS

$ git clone --recurse-submodules https://github.com/greenpdx/IoTCRHTTPS.git
$ cd IoTCRHTTPS

Configure and build project

$ idf.py set-target esp32c3
$ idf.py menuconfig
    Serial flasher config → Flash size  = 4 MB
    Example Connection Configuration → WiFi SSID = test3
    Example Connection Configuration → WiFi Password = test12345
    Component config → ESP System Settings → Channel for console output = USB Serial/JTAG Controller
    Component config → mbedTLS → mbedTLS v3.x related → Support TLS 1.3 protocol = yes
    Component config → mbedTLS → Certificate Bundle → Enable trusted root certificate bundle = no
    Component config → mbedTLS → TLS Protocol Role (Server & Client) = Client
    Component config → LWIP → SNTP → Request NTP servers from DHCP = yes
$ idf.py build
$ idf.py -p /dev/ttyACM0 flash
$ idf.py -p /dev/ttyACM0 monitor