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Introducing self-signed certificates generated on the ESP32 · estx07/esp32_https_server@b37ec0c · GitHub

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Introducing self-signed certificates generated on the ESP32
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‎README.md‎

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@@ -20,7 +20,7 @@ The library is self-contained and just needs the Arduino and ESP32 system librar
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Clone or download the content of this git repository into your Arduino/libraries folder and restart you IDE.
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To run the examples, you need to execute the script extras/create_cert.sh first. This script will create a simple CA to sign certificates that are used with the examples. Some notes on the usage can be found in the extras/README.md file.
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To run the examples (except for the _Self-Signed-Certificates_ example), you need to execute the script extras/create_cert.sh first. This script will create a simple CA to sign certificates that are used with the examples. Some notes on the usage can be found in the extras/README.md file.
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You then should be able to add the library to your project if you selected the ESP32 as architecture.
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- [Async-Server](examples/Async-Server/Async-Server.ino): Like the Static-Page example, but the server runs in a separate task on the ESP32, so you do not need to call the loop() function in your main sketch.
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- [Websocket-Chat](examples/Websocket-Chat/Websocket-Chat.ino): Provides a browser-based chat built on top of websockets. **Note:** Websockets are still under development!
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- [Parameter-Validation](examples/Parameter-Validation/Parameter-Validation.ino): Shows how you can integrate validator functions to do formal checks on parameters in your URL.
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- [Self-Signed-Certificate](examples/Self-Signed/Self-Signed.ino): Shows how to generate a self-signed certificate on the fly on the ESP when the sketch starts. You do not need to run `create_cert.sh` to use this example.
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If you encounter error messages that cert.h or private\_key.h are missing when running an example, make sure to run create\_cert.sh first (see Setup Instructions).
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If you want to have the server running in the background (and not calling `loop()` by yourself every few milliseconds), you can make use of the ESP32's task feature and put the whole server in a separate task.
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See the Async-Server example to see how this can be done.
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See the Async-Server example to see how this can be done.
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## Advanced Configuration
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This section covers some advanced configuration options that allow you e.g. to customize the build process, but which might require more advanced programming skills and a more sophisticated IDE that just the default Arduino IDE.
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### Saving Space by Reducing Functionality
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To save program space on the microcontroller, there are some parts of the library that can be disabled during compilation and will then not be a part of your program.
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The following flags are currently available:
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| Flag | Effect
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| ------------------------- | ---------------------------
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| HTTPS_DISABLE_SELFSIGNING | Removes the code for generating a self-signed certificate at runtime. You will need to provide certificate and private key data from another data source to use the `HTTPSServer`.
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Setting these flags requires a build environment that gives you some control of the compiler, as libraries are usually compiled separately, so just doing a `#define HTTPS_SOMETHING` in your sketch will not work.
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**Example: Configuration with Platform IO**
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To set these flags in Platform IO, you can modify your `platformio.ini`. To disable for example the self-signed-certificates part of the library, the file could look like this:
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```ini
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[env:esp32dev]
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platform = espressif32
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board = esp32dev
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framework = arduino
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build_flags =
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-DHTTPS_DISABLE_SELFSIGNING
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```
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Note the `-D` in front of the actual flag name, that passes this flag as a definition to the preprocessor. Multiple flags can be added one per line.

‎examples/Self-Signed-Certificate/Self-Signed-Certificate.ino‎

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/**
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* Example for the ESP32 HTTP(S) Webserver
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*
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* IMPORTANT NOTE:
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* To run this script, you need to
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* 1) Enter your WiFi SSID and PSK below this comment
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*
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* This script will install an HTTPS Server on your ESP32 with the following
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* functionalities:
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* - Show simple page on web server root
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* - 404 for everything else
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*
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* In contrast to the other examples, the certificate and the private key will be
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* generated on the ESP32, so you do not need to provide them here.
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* (this means no need to run create_cert.sh)
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*/
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// TODO: Configure your WiFi here
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#define WIFI_SSID "<your ssid goes here>"
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#define WIFI_PSK "<your pre-shared key goes here>"
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// We will use wifi
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#include <WiFi.h>
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// Includes for the server
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#include <HTTPSServer.hpp>
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#include <SSLCert.hpp>
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#include <HTTPRequest.hpp>
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#include <HTTPResponse.hpp>
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// The HTTPS Server comes in a separate namespace. For easier use, include it here.
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using namespace httpsserver;
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SSLCert * cert;
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HTTPSServer * secureServer;
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// Declare some handler functions for the various URLs on the server
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void handleRoot(HTTPRequest * req, HTTPResponse * res);
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void handle404(HTTPRequest * req, HTTPResponse * res);
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void setup() {
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// For logging
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Serial.begin(115200);
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delay(3000); // wait for the monitor to reconnect after uploading.
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Serial.println("Creating a new self-signed certificate.");
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Serial.println("This may take up to a minute, so be patient ;-)");
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// First, we create an empty certificate:
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cert = new SSLCert();
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// Now, we use the function createSelfSignedCert to create private key and certificate.
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// The function takes the following paramters:
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// - Key size: 1024 or 2048 bit should be fine here, 4096 on the ESP might be "paranoid mode"
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// (in generel: shorter key = faster but less secure)
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// - Distinguished name: The name of the host as used in certificates.
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// If you want to run your own DNS, the part after CN (Common Name) should match the DNS
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// entry pointing to your ESP32. You can try to insert an IP there, but that's not really good style.
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int createCertResult = createSelfSignedCert(*cert, KEYSIZE_2048, "CN=myesp32.local,O=FancyCompany,C=DE");
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// Now check if creating that worked
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if (createCertResult != 0) {
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Serial.printf("Cerating certificate failed. Error Code = 0x%02X, check SSLCert.hpp for details", createCertResult);
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while(true) delay(500);
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}
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Serial.println("Creating the certificate was successful");
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// If you're working on a serious project, this would be a good place to initialize some form of non-volatile storage
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// and to put the certificate and the key there. This has the advantage that the certificate stays the same after a reboot
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// so your client still trusts your server, additionally you increase the speed-up of your application.
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// Some browsers like Firefox might even reject the second run for the same issuer name (the distinguished name defined above).
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//
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// Storing:
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// For the key:
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// cert->getPKLength() will return the length of the private key in byte
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// cert->getPKData() will return the actual private key (in DER-format, if that matters to you)
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// For the certificate:
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// cert->getCertLength() and ->getCertData() do the same for the actual certificate data.
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// Restoring:
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// When your applications boots, check your non-volatile storage for an existing certificate, and if you find one
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// use the parameterized SSLCert constructor to re-create the certificate and pass it to the HTTPSServer.
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//
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// A short reminder on key security: If you're working on something professional, be aware that the storage of the ESP32 is
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// not encrypted in any way. This means that if you just write it to the flash storage, it is easy to extract it if someone
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// gets a hand on your hardware. You should decide if that's a relevant risk for you and apply countermeasures like flash
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// encryption if neccessary
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// We can now use the new certificate to setup our server as usual.
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secureServer = new HTTPSServer(cert);
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// Connect to WiFi
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Serial.println("Setting up WiFi");
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WiFi.begin(WIFI_SSID, WIFI_PSK);
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while (WiFi.status() != WL_CONNECTED) {
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Serial.print(".");
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delay(500);
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}
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Serial.print("Connected. IP=");
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Serial.println(WiFi.localIP());
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// For every resource available on the server, we need to create a ResourceNode
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// The ResourceNode links URL and HTTP method to a handler function
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ResourceNode * nodeRoot = new ResourceNode("/", "GET", &handleRoot);
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ResourceNode * node404 = new ResourceNode("", "GET", &handle404);
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// Add the root node to the server
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secureServer->registerNode(nodeRoot);
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// Add the 404 not found node to the server.
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secureServer->setDefaultNode(node404);
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Serial.println("Starting server...");
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secureServer->start();
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if (secureServer->isRunning()) {
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Serial.println("Server ready.");
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}
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}
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void loop() {
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// This call will let the server do its work
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secureServer->loop();
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// Other code would go here...
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delay(1);
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}
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void handleRoot(HTTPRequest * req, HTTPResponse * res) {
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// Status code is 200 OK by default.
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// We want to deliver a simple HTML page, so we send a corresponding content type:
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res->setHeader("Content-Type", "text/html");
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// The response implements the Print interface, so you can use it just like
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// you would write to Serial etc.
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res->println("<!DOCTYPE html>");
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res->println("<html>");
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res->println("<head><title>Hello World!</title></head>");
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res->println("<body>");
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res->println("<h1>Hello World!</h1>");
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res->print("<p>Your server is running for ");
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// A bit of dynamic data: Show the uptime
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res->print((int)(millis()/1000), DEC);
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res->println(" seconds.</p>");
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res->println("</body>");
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res->println("</html>");
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}
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void handle404(HTTPRequest * req, HTTPResponse * res) {
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// Discard request body, if we received any
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// We do this, as this is the default node and may also server POST/PUT requests
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req->discardRequestBody();
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// Set the response status
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res->setStatusCode(404);
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res->setStatusText("Not Found");
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// Set content type of the response
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res->setHeader("Content-Type", "text/html");
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// Write a tiny HTTP page
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res->println("<!DOCTYPE html>");
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res->println("<html>");
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res->println("<head><title>Not Found</title></head>");
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res->println("<body><h1>404 Not Found</h1><p>The requested resource was not found on this server.</p></body>");
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res->println("</html>");
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}

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