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Rework WiFiClientSecure into SSLClient which works with any Client-derived class. Tested with ESP32 WiFiClient and TinyGsmClient.
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Diff for: ‎libraries/SSLClient/README.md

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SSLClient
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=========
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The SSLClient class implements support for secure connections using TLS (SSL).
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It inherits from Client and thus implements a superset of that class' interface.
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There are three ways to establish a secure connection using the SSLClient class:
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using a root certificate authority (CA) cert, using a root CA cert plus a client cert and key,
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and using a pre-shared key (PSK).
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Using a root certificate authority cert
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---------------------------------------
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This method authenticates the server and negotiates an encrypted connection.
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It is the same functionality as implemented in your web browser when you connect to HTTPS sites.
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If you are accessing your own server:
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- Generate a root certificate for your own certificate authority
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- Generate a cert & private key using your root certificate ("self-signed cert") for your server
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If you are accessing a public server:
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- Obtain the cert of the public CA that signed that server's cert
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Then:
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- In SSLClient use setCACert (or the appropriate connect method) to set the root cert of your
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CA or of the public CA
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- When SSLClient connects to the target server it uses the CA cert to verify the certificate
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presented by the server, and then negotiates encryption for the connection
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Please see the SSLClient example.
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Using a root CA cert and client cert/keys
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-----------------------------------------
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This method authenticates the server and additionally also authenticates
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the client to the server, then negotiates an encrypted connection.
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- Follow steps above
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- Using your root CA generate cert/key for your client
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- Register the keys with the server you will be accessing so the server can authenticate your client
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- In SSLClient use setCACert (or the appropriate connect method) to set the root cert of your
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CA or of the public CA, this is used to authenticate the server
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- In SSLClient use setCertificate, and setPrivateKey (or the appropriate connect method) to
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set your client's cert & key, this will be used to authenticate your client to the server
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- When SSLClient connects to the target server it uses the CA cert to verify the certificate
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presented by the server, it will use the cert/key to authenticate your client to the server, and
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it will then negotiate encryption for the connection
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Using Pre-Shared Keys (PSK)
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---------------------------
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TLS supports authentication and encryption using a pre-shared key (i.e. a key that both client and
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server know) as an alternative to the public key cryptography commonly used on the web for HTTPS.
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PSK is starting to be used for MQTT, e.g. in mosquitto, to simplify the set-up and avoid having to
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go through the whole CA, cert, and private key process.
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A pre-shared key is a binary string of up to 32 bytes and is commonly represented in hex form. In
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addition to the key, clients can also present an id and typically the server allows a different key
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to be associated with each client id. In effect this is very similar to username and password pairs,
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except that unlike a password the key is not directly transmitted to the server, thus a connection to a
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malicious server does not divulge the password. Plus the server is also authenticated to the client.
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To use PSK:
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- Generate a random hex string (generating an MD5 or SHA for some file is one way to do this)
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- Come up with a string id for your client and configure your server to accept the id/key pair
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- In SSLClient use setPreSharedKey (or the appropriate connect method) to
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set the id/key combo
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- When SSLClient connects to the target server it uses the id/key combo to authenticate the
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server (it must prove that it has the key too), authenticate the client and then negotiate
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encryption for the connection
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Please see the SSLClientPSK example.
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Specifying the ALPN Protocol
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----------------------------
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Application-Layer Protocol Negotiation (ALPN) is a Transport Layer Security (TLS) extension that allows
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the application layer to negotiate which protocol should be performed over a secure connection in a manner
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that avoids additional round trips and which is independent of the application-layer protocols.
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For example, this is used with AWS IoT Custom Authorizers where an MQTT client must set the ALPN protocol to ```mqtt```:
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```
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const char *aws_protos[] = {"mqtt", NULL};
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...
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sslClient.setAlpnProtocols(aws_protos);
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```

Diff for: ‎libraries/SSLClient/examples/WiFiClientInsecure/WiFiClientInsecure.ino

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#include <WiFi.h>
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#include <SSLClient.h>
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const char* ssid = "your-ssid"; // your network SSID (name of wifi network)
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const char* password = "your-password"; // your network password
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const char* server = "www.howsmyssl.com"; // Server URL
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WiFiClient wificlient;
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SSLClient client(wificlient);
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void setup() {
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//Initialize serial and wait for port to open:
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Serial.begin(115200);
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delay(100);
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Serial.print("Attempting to connect to SSID: ");
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Serial.println(ssid);
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WiFi.begin(ssid, password);
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// attempt to connect to Wifi network:
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while (WiFi.status() != WL_CONNECTED) {
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Serial.print(".");
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// wait 1 second for re-trying
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delay(1000);
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}
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Serial.print("Connected to ");
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Serial.println(ssid);
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Serial.println("\nStarting connection to server...");
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client.setInsecure();//skip verification
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if (!client.connect(server, 443))
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Serial.println("Connection failed!");
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else {
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Serial.println("Connected to server!");
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// Make a HTTP request:
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client.println("GET https://www.howsmyssl.com/a/check HTTP/1.0");
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client.println("Host: www.howsmyssl.com");
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client.println("Connection: close");
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client.println();
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while (client.connected()) {
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String line = client.readStringUntil('\n');
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if (line == "\r") {
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Serial.println("headers received");
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break;
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}
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}
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// if there are incoming bytes available
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// from the server, read them and print them:
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while (client.available()) {
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char c = client.read();
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Serial.write(c);
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}
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client.stop();
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}
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}
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void loop() {
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// do nothing
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}

Diff for: ‎libraries/SSLClient/examples/WiFiClientPSK/WiFiClientPSK.ino

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/*
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Wifi secure connection example for ESP32 using a pre-shared key (PSK)
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This is useful with MQTT servers instead of using a self-signed cert, tested with mosquitto.
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Running on TLS 1.2 using mbedTLS
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To test run a test server using: openssl s_server -accept 8443 -psk 1a2b3c4d -nocert
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It will show the http request made, but there's no easy way to send a reply back...
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2017 - Evandro Copercini - Apache 2.0 License.
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2018 - Adapted for PSK by Thorsten von Eicken
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*/
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#include <WiFi.h>
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#include <SSLClient.h>
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#if 0
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const char* ssid = "your-ssid"; // your network SSID (name of wifi network)
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const char* password = "your-password"; // your network password
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#else
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const char* ssid = "test"; // your network SSID (name of wifi network)
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const char* password = "securetest"; // your network password
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#endif
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//const char* server = "server.local"; // Server hostname
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const IPAddress server = IPAddress(192, 168, 0, 14); // Server IP address
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const int port = 8443; // server's port (8883 for MQTT)
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const char* pskIdent = "Client_identity"; // PSK identity (sometimes called key hint)
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const char* psKey = "1a2b3c4d"; // PSK Key (must be hex string without 0x)
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WiFiClient wificlient;
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SSLClient client(wificlient);
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void setup() {
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//Initialize serial and wait for port to open:
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Serial.begin(115200);
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delay(100);
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Serial.print("Attempting to connect to SSID: ");
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Serial.println(ssid);
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WiFi.begin(ssid, password);
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// attempt to connect to Wifi network:
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while (WiFi.status() != WL_CONNECTED) {
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Serial.print(".");
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// wait 1 second for re-trying
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delay(1000);
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}
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Serial.print("Connected to ");
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Serial.println(ssid);
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client.setPreSharedKey(pskIdent, psKey);
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Serial.println("\nStarting connection to server...");
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if (!client.connect(server, port))
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Serial.println("Connection failed!");
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else {
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Serial.println("Connected to server!");
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// Make a HTTP request:
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client.println("GET /a/check HTTP/1.0");
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client.print("Host: ");
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client.println(server);
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client.println("Connection: close");
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client.println();
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while (client.connected()) {
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String line = client.readStringUntil('\n');
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if (line == "\r") {
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Serial.println("headers received");
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break;
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}
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}
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// if there are incoming bytes available
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// from the server, read them and print them:
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while (client.available()) {
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char c = client.read();
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Serial.write(c);
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}
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client.stop();
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}
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}
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void loop() {
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// do nothing
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}

Diff for: ‎libraries/SSLClient/examples/WiFiClientSecure/WiFiClientSecure.ino

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/*
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Wifi secure connection example for ESP32
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Running on TLS 1.2 using mbedTLS
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Suporting the following chipersuites:
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"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384","TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384","TLS_DHE_RSA_WITH_AES_256_GCM_SHA384","TLS_ECDHE_ECDSA_WITH_AES_256_CCM","TLS_DHE_RSA_WITH_AES_256_CCM","TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384","TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384","TLS_DHE_RSA_WITH_AES_256_CBC_SHA256","TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA","TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA","TLS_DHE_RSA_WITH_AES_256_CBC_SHA","TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8","TLS_DHE_RSA_WITH_AES_256_CCM_8","TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_GCM_SHA384","TLS_ECDHE_RSA_WITH_CAMELLIA_256_GCM_SHA384","TLS_DHE_RSA_WITH_CAMELLIA_256_GCM_SHA384","TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384","TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384","TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256","TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA","TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256","TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256","TLS_DHE_RSA_WITH_AES_128_GCM_SHA256","TLS_ECDHE_ECDSA_WITH_AES_128_CCM","TLS_DHE_RSA_WITH_AES_128_CCM","TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256","TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256","TLS_DHE_RSA_WITH_AES_128_CBC_SHA256","TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA","TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA","TLS_DHE_RSA_WITH_AES_128_CBC_SHA","TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8","TLS_DHE_RSA_WITH_AES_128_CCM_8","TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_GCM_SHA256","TLS_ECDHE_RSA_WITH_CAMELLIA_128_GCM_SHA256","TLS_DHE_RSA_WITH_CAMELLIA_128_GCM_SHA256","TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256","TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256","TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256","TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA","TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA","TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA","TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA","TLS_DHE_PSK_WITH_AES_256_GCM_SHA384","TLS_DHE_PSK_WITH_AES_256_CCM","TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384","TLS_DHE_PSK_WITH_AES_256_CBC_SHA384","TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA","TLS_DHE_PSK_WITH_AES_256_CBC_SHA","TLS_DHE_PSK_WITH_CAMELLIA_256_GCM_SHA384","TLS_ECDHE_PSK_WITH_CAMELLIA_256_CBC_SHA384","TLS_DHE_PSK_WITH_CAMELLIA_256_CBC_SHA384","TLS_PSK_DHE_WITH_AES_256_CCM_8","TLS_DHE_PSK_WITH_AES_128_GCM_SHA256","TLS_DHE_PSK_WITH_AES_128_CCM","TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256","TLS_DHE_PSK_WITH_AES_128_CBC_SHA256","TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA","TLS_DHE_PSK_WITH_AES_128_CBC_SHA","TLS_DHE_PSK_WITH_CAMELLIA_128_GCM_SHA256","TLS_DHE_PSK_WITH_CAMELLIA_128_CBC_SHA256","TLS_ECDHE_PSK_WITH_CAMELLIA_128_CBC_SHA256","TLS_PSK_DHE_WITH_AES_128_CCM_8","TLS_ECDHE_PSK_WITH_3DES_EDE_CBC_SHA","TLS_DHE_PSK_WITH_3DES_EDE_CBC_SHA","TLS_RSA_WITH_AES_256_GCM_SHA384","TLS_RSA_WITH_AES_256_CCM","TLS_RSA_WITH_AES_256_CBC_SHA256","TLS_RSA_WITH_AES_256_CBC_SHA","TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384","TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384","TLS_ECDH_RSA_WITH_AES_256_CBC_SHA","TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384","TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384","TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA","TLS_RSA_WITH_AES_256_CCM_8","TLS_RSA_WITH_CAMELLIA_256_GCM_SHA384","TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256","TLS_RSA_WITH_CAMELLIA_256_CBC_SHA","TLS_ECDH_RSA_WITH_CAMELLIA_256_GCM_SHA384","TLS_ECDH_RSA_WITH_CAMELLIA_256_CBC_SHA384","TLS_ECDH_ECDSA_WITH_CAMELLIA_256_GCM_SHA384","TLS_ECDH_ECDSA_WITH_CAMELLIA_256_CBC_SHA384","TLS_RSA_WITH_AES_128_GCM_SHA256","TLS_RSA_WITH_AES_128_CCM","TLS_RSA_WITH_AES_128_CBC_SHA256","TLS_RSA_WITH_AES_128_CBC_SHA","TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256","TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256","TLS_ECDH_RSA_WITH_AES_128_CBC_SHA","TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256","TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256","TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA","TLS_RSA_WITH_AES_128_CCM_8","TLS_RSA_WITH_CAMELLIA_128_GCM_SHA256","TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256","TLS_RSA_WITH_CAMELLIA_128_CBC_SHA","TLS_ECDH_RSA_WITH_CAMELLIA_128_GCM_SHA256","TLS_ECDH_RSA_WITH_CAMELLIA_128_CBC_SHA256","TLS_ECDH_ECDSA_WITH_CAMELLIA_128_GCM_SHA256","TLS_ECDH_ECDSA_WITH_CAMELLIA_128_CBC_SHA256","TLS_RSA_WITH_3DES_EDE_CBC_SHA","TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA","TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA","TLS_RSA_PSK_WITH_AES_256_GCM_SHA384","TLS_RSA_PSK_WITH_AES_256_CBC_SHA384","TLS_RSA_PSK_WITH_AES_256_CBC_SHA","TLS_RSA_PSK_WITH_CAMELLIA_256_GCM_SHA384","TLS_RSA_PSK_WITH_CAMELLIA_256_CBC_SHA384","TLS_RSA_PSK_WITH_AES_128_GCM_SHA256","TLS_RSA_PSK_WITH_AES_128_CBC_SHA256","TLS_RSA_PSK_WITH_AES_128_CBC_SHA","TLS_RSA_PSK_WITH_CAMELLIA_128_GCM_SHA256","TLS_RSA_PSK_WITH_CAMELLIA_128_CBC_SHA256","TLS_RSA_PSK_WITH_3DES_EDE_CBC_SHA","TLS_PSK_WITH_AES_256_GCM_SHA384","TLS_PSK_WITH_AES_256_CCM","TLS_PSK_WITH_AES_256_CBC_SHA384","TLS_PSK_WITH_AES_256_CBC_SHA","TLS_PSK_WITH_CAMELLIA_256_GCM_SHA384","TLS_PSK_WITH_CAMELLIA_256_CBC_SHA384","TLS_PSK_WITH_AES_256_CCM_8","TLS_PSK_WITH_AES_128_GCM_SHA256","TLS_PSK_WITH_AES_128_CCM","TLS_PSK_WITH_AES_128_CBC_SHA256","TLS_PSK_WITH_AES_128_CBC_SHA","TLS_PSK_WITH_CAMELLIA_128_GCM_SHA256","TLS_PSK_WITH_CAMELLIA_128_CBC_SHA256","TLS_PSK_WITH_AES_128_CCM_8","TLS_PSK_WITH_3DES_EDE_CBC_SHA","TLS_EMPTY_RENEGOTIATION_INFO_SCSV"]
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2017 - Evandro Copercini - Apache 2.0 License.
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*/
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#include <WiFi.h>
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#include <SSLClient.h>
11+
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const char* ssid = "your-ssid"; // your network SSID (name of wifi network)
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const char* password = "your-password"; // your network password
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const char* server = "www.howsmyssl.com"; // Server URL
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// www.howsmyssl.com root certificate authority, to verify the server
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// change it to your server root CA
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// SHA1 fingerprint is broken now!
20+
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const char* test_root_ca= \
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"-----BEGIN CERTIFICATE-----\n" \
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"MIIDSjCCAjKgAwIBAgIQRK+wgNajJ7qJMDmGLvhAazANBgkqhkiG9w0BAQUFADA/\n" \
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"MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT\n" \
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"DkRTVCBSb290IENBIFgzMB4XDTAwMDkzMDIxMTIxOVoXDTIxMDkzMDE0MDExNVow\n" \
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"PzEkMCIGA1UEChMbRGlnaXRhbCBTaWduYXR1cmUgVHJ1c3QgQ28uMRcwFQYDVQQD\n" \
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"Ew5EU1QgUm9vdCBDQSBYMzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEB\n" \
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"AN+v6ZdQCINXtMxiZfaQguzH0yxrMMpb7NnDfcdAwRgUi+DoM3ZJKuM/IUmTrE4O\n" \
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"rz5Iy2Xu/NMhD2XSKtkyj4zl93ewEnu1lcCJo6m67XMuegwGMoOifooUMM0RoOEq\n" \
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"OLl5CjH9UL2AZd+3UWODyOKIYepLYYHsUmu5ouJLGiifSKOeDNoJjj4XLh7dIN9b\n" \
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"xiqKqy69cK3FCxolkHRyxXtqqzTWMIn/5WgTe1QLyNau7Fqckh49ZLOMxt+/yUFw\n" \
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"7BZy1SbsOFU5Q9D8/RhcQPGX69Wam40dutolucbY38EVAjqr2m7xPi71XAicPNaD\n" \
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"aeQQmxkqtilX4+U9m5/wAl0CAwEAAaNCMEAwDwYDVR0TAQH/BAUwAwEB/zAOBgNV\n" \
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"HQ8BAf8EBAMCAQYwHQYDVR0OBBYEFMSnsaR7LHH62+FLkHX/xBVghYkQMA0GCSqG\n" \
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"SIb3DQEBBQUAA4IBAQCjGiybFwBcqR7uKGY3Or+Dxz9LwwmglSBd49lZRNI+DT69\n" \
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"ikugdB/OEIKcdBodfpga3csTS7MgROSR6cz8faXbauX+5v3gTt23ADq1cEmv8uXr\n" \
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"AvHRAosZy5Q6XkjEGB5YGV8eAlrwDPGxrancWYaLbumR9YbK+rlmM6pZW87ipxZz\n" \
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"R8srzJmwN0jP41ZL9c8PDHIyh8bwRLtTcm1D9SZImlJnt1ir/md2cXjbDaJWFBM5\n" \
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"JDGFoqgCWjBH4d1QB7wCCZAA62RjYJsWvIjJEubSfZGL+T0yjWW06XyxV3bqxbYo\n" \
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"Ob8VZRzI9neWagqNdwvYkQsEjgfbKbYK7p2CNTUQ\n" \
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"-----END CERTIFICATE-----\n";
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// You can use x.509 client certificates if you want
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//const char* test_client_key = ""; //to verify the client
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//const char* test_client_cert = ""; //to verify the client
46+
47+
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WiFiClient wificlient;
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SSLClient client(wificlient);
50+
51+
void setup() {
52+
//Initialize serial and wait for port to open:
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Serial.begin(115200);
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delay(100);
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Serial.print("Attempting to connect to SSID: ");
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Serial.println(ssid);
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WiFi.begin(ssid, password);
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// attempt to connect to Wifi network:
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while (WiFi.status() != WL_CONNECTED) {
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Serial.print(".");
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// wait 1 second for re-trying
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delay(1000);
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}
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Serial.print("Connected to ");
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Serial.println(ssid);
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client.setCACert(test_root_ca);
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//client.setCertificate(test_client_cert); // for client verification
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//client.setPrivateKey(test_client_key); // for client verification
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Serial.println("\nStarting connection to server...");
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if (!client.connect(server, 443))
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Serial.println("Connection failed!");
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else {
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Serial.println("Connected to server!");
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// Make a HTTP request:
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client.println("GET https://www.howsmyssl.com/a/check HTTP/1.0");
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client.println("Host: www.howsmyssl.com");
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client.println("Connection: close");
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client.println();
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while (client.connected()) {
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String line = client.readStringUntil('\n');
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if (line == "\r") {
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Serial.println("headers received");
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break;
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}
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}
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// if there are incoming bytes available
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// from the server, read them and print them:
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while (client.available()) {
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char c = client.read();
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Serial.write(c);
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}
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client.stop();
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}
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}
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void loop() {
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// do nothing
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}

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