Java: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

Question

I have a class that will download a file from a https server. When I run it, it returns a lot of errors. It seems that I have a problem with my certificate

Answer 1

There is a lot of way to solve this...

One way is set the TrustStore certificates in a keystore file and put it in the path of the application, and set these system properties in the main method:

public static void main(String[] args) {
  System.setProperty("javax.net.ssl.trustStore", "trust-store.jks");
  System.setProperty("javax.net.ssl.trustStorePassword", "TrustStore");
  ...
}

Other way is place the keystore as resource file inside the project jar file and load it:

public static SSLContext createSSLContext(String resourcePath, String pass) throws NoSuchAlgorithmException, KeyStoreException, IOException, CertificateException, UnrecoverableKeyException, KeyManagementException {
  // initialise the keystore
  final char[] password = pass.toCharArray();
  KeyStore ks = KeyStore.getInstance("JKS");
  ks.load(ThisClass.class.getResourceAsStream(resourcePath
  ), password);

  // Setup the key manager factory.
  KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
  kmf.init(ks, password);

  // Setup the trust manager factory.
  TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509");
  tmf.init(ks);

  SSLContext sslc = SSLContext.getInstance("TLS");
  sslc.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);
  return sslc;
}

public static void main(String[] args) {
  SSLContext.setDefault(
    createSSLContext("/trust-store.jks", "TrustStore"));
  ...
}

In windows you can try this solution too: https://stackoverflow.com/a/59056537/980442

---

I created the keystore file from a Certificate authority CA .crt file in this way:

keytool -import -alias ca -keystore trust-store.jks -storepass TrustStore -trustcacerts -file ca.crt

FYI: https://docs.oracle.com/javadb/10.8.3.0/adminguide/cadminsslclient.html