Disable Certificate Validation in Java SSL Connections
By design when we open an SSL connection in Java (e.g. through java.net.URL.openConnection(“https://….”)) the JSSE implementation of the SSL protocol performs few validations to ensure the requested host is not fake. This involves validation of the server’s X.509 certificate with the PKIX algorithm and checking the host name agains the certificate subject. If the SSL certificate is not validates as trusted or does not match the target host, an HTTPS and other SSL encrypted connection cannot be established and all attempts will result in SSLHandshakeException or IOException.
Example of HTTPS Connection in Java that will Fail Due to Certificate Validation Failure
Consider we are trying to download a resource from HTTPS server:
URLConnection con = url.openConnection();Reader reader = new InputStreamReader(con.getInputStream());while (true) { int ch = reader.read(); if (ch==-1) { break; } System.out.print((char)ch);}
If the server uses self-signed X.509 certificate, we will get SSLHandshakeException the following exception during the SSL handshaking:
Exception in thread "main" <strong>java.io.IOException: HTTPS hostname wrong: should be <www.nakov.com></strong>
at sun.net.www.protocol.https.HttpsClient.checkURLSpoofing(Unknown Source)
at sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
How to Turn Off Certificate Validation in Java HTTPS Connections
Avoiding these exceptions is possible by switching off the certificate validation and host verification for SSL for the current Java virtual machine. This can be done by replacing the default SSL trust manager and the default SSL hostname verifier:
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.net.URLConnection;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.security.cert.X509Certificate;
public class Example {
public static void main(String[] args) throws Exception {
// Create a trust manager that does not validate certificate chains
TrustManager[] trustAllCerts = new TrustManager[] {new X509TrustManager() {
public java.security.cert.X509Certificate[] getAcceptedIssuers() {
return null;
}
public void checkClientTrusted(X509Certificate[] certs, String authType) {
}
public void checkServerTrusted(X509Certificate[] certs, String authType) {
}
}
};
// Install the all-trusting trust manager
SSLContext sc = SSLContext.getInstance("SSL");
sc.init(null, trustAllCerts, new java.security.SecureRandom());
HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
// Create all-trusting host name verifier
HostnameVerifier allHostsValid = new HostnameVerifier() {
public boolean verify(String hostname, SSLSession session) {
return true;
}
};
// Install the all-trusting host verifier
HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);
URL url = new URL("https://www.nakov.com:2083/");
URLConnection con = url.openConnection();
Reader reader = new InputStreamReader(con.getInputStream());
while (true) {
int ch = reader.read();
if (ch==-1) {
break;
}
System.out.print((char)ch);
}
}
}
