Root Certificate
For secure HTTPS connections from devices like Arduino or ESP32. This GlobalSign root certificate is widely compatible with devices that may not support newer signature algorithms.
const char* root_ca = "-----BEGIN CERTIFICATE-----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\npOMYo22dM3iHh/I/d32p8DAA==\n-----END CERTIFICATE-----\n";
Instructions for Arduino:
1. Copy the C-style string above.
2. Paste it into your Arduino sketch.
3. For WiFiClientSecure, use client.setCACert(root_ca); before connecting.