ssl_pinning_demo.kt

// Read the pinned certificate from local (i.e., assets folder)
val inputStream = context.assets.open("google.crt")
val pinnedCertificate = CertificateFactory.getInstance("X.509")
    .generateCertificate(inputStream)

// Create a request to www.google.com
val url = URL("https://www.google.com")
val httpsUrlConnection = url.openConnection() as HttpsURLConnection

// Establish the connection
httpsUrlConnection.connect()

// Check the certificates and see if one of the server certificates 
// matches the pinned certificate
if (httpsUrlConnection.serverCertificates.contains(pinnedCertificate)) {
    // Open stream
    httpsUrlConnection.inputStream
    Log.d("Pinning", "Server certificates validation successful")
} else {
    Log.d("Pinning", "Server certificates validation failed")
    throw SSLException("Server certificates validation failed for google.com")
}