Accept server's self-signed ssl certificate in Java client

Question

It looks like a standard question, but I couldn't find clear directions anywhere.

I have java code trying to connect to a server with probably self-signed (or expired) certificate. The code reports the following error :

[HttpMethodDirector] I/O exception (javax.net.ssl.SSLHandshakeException) caught 
when processing request: sun.security.validator.ValidatorException: PKIX path 
building failed: sun.security.provider.certpath.SunCertPathBuilderException: 
unable to find valid certification path to requested target

As I understand it, I have to use keytool and tell java that it's OK to allow this connection.

All instructions to fix this problem assume I'm fully proficient with keytool, such as

generate private key for server and import it into keystore

Is there anybody who could post detailed instructions?

I'm running unix, so bash script would be best.

Not sure if it's important, but code executed in jboss.

Answer 1

You have basically two options here: add the self-signed certificate to your JVM truststore or configure your client to

Option 1

Export the certificate from your browser and import it in your JVM truststore (to establish a chain of trust):

<JAVA_HOME>\bin\keytool -import -v -trustcacerts
-alias server-alias -file server.cer
-keystore cacerts.jks -keypass changeit
-storepass changeit 

Option 2

Disable Certificate Validation:

// Create a trust manager that does not validate certificate chains
TrustManager[] trustAllCerts = new TrustManager[] { 
    new X509TrustManager() {     
        public java.security.cert.X509Certificate[] getAcceptedIssuers() { 
            return new X509Certificate[0];
        } 
        public void checkClientTrusted( 
            java.security.cert.X509Certificate[] certs, String authType) {
            } 
        public void checkServerTrusted( 
            java.security.cert.X509Certificate[] certs, String authType) {
        }
    } 
}; 

// Install the all-trusting trust manager
try {
    SSLContext sc = SSLContext.getInstance("SSL"); 
    sc.init(null, trustAllCerts, new java.security.SecureRandom()); 
    HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
} catch (GeneralSecurityException e) {
} 
// Now you can access an https URL without having the certificate in the truststore
try { 
    URL url = new URL("https://hostname/index.html"); 
} catch (MalformedURLException e) {
} 

Note that I do not recommend the Option #2 at all. Disabling the trust manager defeats some parts of SSL and makes you vulnerable to man in the middle attacks. Prefer Option #1 or, even better, have the server use a "real" certificate signed by a well known CA.

Answer 2

I chased down this problem to a certificate provider that is not part of the default JVM trusted hosts as of JDK 8u74. The provider is www.identrust.com, but that was not the domain I was trying to connect to. That domain had gotten its certificate from this provider. See Will the cross root cover trust by the default list in the JDK/JRE? -- read down a couple entries. Also see Which browsers and operating systems support Let’s Encrypt.

So, in order to connect to the domain I was interested in, which had a certificate issued from identrust.com I did the following steps. Basically, I had to get the identrust.com (DST Root CA X3) certificate to be trusted by the JVM. I was able to do that using Apache HttpComponents 4.5 like so:

1: Obtain the certificate from indettrust at Certificate Chain Download Instructions. Click on the DST Root CA X3 link.

2: Save the string to a file named "DST Root CA X3.pem". Be sure to add the lines "-----BEGIN CERTIFICATE-----" and "-----END CERTIFICATE-----" in the file at the beginning and the end.

3: Create a java keystore file, cacerts.jks with the following command:

keytool -import -v -trustcacerts -alias IdenTrust -keypass yourpassword -file dst_root_ca_x3.pem -keystore cacerts.jks -storepass yourpassword

4: Copy the resulting cacerts.jks keystore into the resources directory of your java/(maven) application.

5: Use the following code to load this file and attach it to the Apache 4.5 HttpClient. This will solve the problem for all domains that have certificates issued from indetrust.com util oracle includes the certificate into the JRE default keystore.

SSLContext sslcontext = SSLContexts.custom()
        .loadTrustMaterial(new File(CalRestClient.class.getResource("/cacerts.jks").getFile()), "yourpasword".toCharArray(),
                new TrustSelfSignedStrategy())
        .build();
// Allow TLSv1 protocol only
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
        sslcontext,
        new String[] { "TLSv1" },
        null,
        SSLConnectionSocketFactory.getDefaultHostnameVerifier());
CloseableHttpClient httpclient = HttpClients.custom()
        .setSSLSocketFactory(sslsf)
        .build();

When the project builds then the cacerts.jks will be copied into the classpath and loaded from there. I didn't, at this point in time, test against other ssl sites, but if the above code "chains" in this certificate then they will work too, but again, I don't know.

Reference: Custom SSL context and How do I accept a self-signed certificate with a Java HttpsURLConnection?

Answer 3

Apache HttpClient 4.5 supports accepting self-signed certificates:

SSLContext sslContext = SSLContexts.custom()
    .loadTrustMaterial(new TrustSelfSignedStrategy())
    .build();
SSLConnectionSocketFactory socketFactory =
    new SSLConnectionSocketFactory(sslContext);
Registry<ConnectionSocketFactory> reg =
    RegistryBuilder.<ConnectionSocketFactory>create()
    .register("https", socketFactory)
    .build();
HttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(reg);        
CloseableHttpClient httpClient = HttpClients.custom()
    .setConnectionManager(cm)
    .build();
HttpGet httpGet = new HttpGet(url);
CloseableHttpResponse sslResponse = httpClient.execute(httpGet);

This builds an SSL socket factory which will use the TrustSelfSignedStrategy, registers it with a custom connection manager then does an HTTP GET using that connection manager.

I agree with those who chant "don't do this in production", however there are use-cases for accepting self-signed certificates outside production; we use them in automated integration tests, so that we're using SSL (like in production) even when not running on the production hardware.

Answer 4

Rather than setting the default socket factory (which IMO is a bad thing) - yhis will just affect the current connection rather than every SSL connection you try to open:

URLConnection connection = url.openConnection();
    // JMD - this is a better way to do it that doesn't override the default SSL factory.
    if (connection instanceof HttpsURLConnection)
    {
        HttpsURLConnection conHttps = (HttpsURLConnection) connection;
        // Set up a Trust all manager
        TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager()
        {

            public java.security.cert.X509Certificate[] getAcceptedIssuers()
            {
                return null;
            }

            public void checkClientTrusted(
                java.security.cert.X509Certificate[] certs, String authType)
            {
            }

            public void checkServerTrusted(
                java.security.cert.X509Certificate[] certs, String authType)
            {
            }
        } };

        // Get a new SSL context
        SSLContext sc = SSLContext.getInstance("TLSv1.2");
        sc.init(null, trustAllCerts, new java.security.SecureRandom());
        // Set our connection to use this SSL context, with the "Trust all" manager in place.
        conHttps.setSSLSocketFactory(sc.getSocketFactory());
        // Also force it to trust all hosts
        HostnameVerifier allHostsValid = new HostnameVerifier() {
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        };
        // and set the hostname verifier.
        conHttps.setHostnameVerifier(allHostsValid);
    }
InputStream stream = connection.getInputStream();

Answer 5

Trust all SSL certificates:- You can bypass SSL if you want to test on the testing server. But do not use this code for production.

public static class NukeSSLCerts {
protected static final String TAG = "NukeSSLCerts";

public static void nuke() {
    try {
        TrustManager[] trustAllCerts = new TrustManager[] { 
            new X509TrustManager() {
                public X509Certificate[] getAcceptedIssuers() {
                    X509Certificate[] myTrustedAnchors = new X509Certificate[0];  
                    return myTrustedAnchors;
                }

                @Override
                public void checkClientTrusted(X509Certificate[] certs, String authType) {}

                @Override
                public void checkServerTrusted(X509Certificate[] certs, String authType) {}
            }
        };

        SSLContext sc = SSLContext.getInstance("SSL");
        sc.init(null, trustAllCerts, new SecureRandom());
        HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
        HttpsURLConnection.setDefaultHostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String arg0, SSLSession arg1) {
                return true;
            }
        });
    } catch (Exception e) { 
    }
}

}

Please call this function in onCreate() function in Activity or in your Application Class.

NukeSSLCerts.nuke();

This can be used for Volley in Android.

Answer 6

If 'they' are using a self-signed certificate it is up to them to take the steps required to make their server usable. Specifically that means providing their certificate to you offline in a trustworthy way. So get them to do that. You then import that into your truststore using the keytool as described in the JSSE Reference Guide. Don't even think about the insecure TrustManager posted here.

EDIT For the benefit of the seventeen (!) downvoters, and numerous commenters below, who clearly have not actually read what I have written here, this is not a jeremiad against self-signed certificates. There is nothing wrong with self-signed certificates when implemented correctly. But, the correct way to implement them is to have the certificate delivered securely via an offline process, rather than via the unauthenticated channel they are going to be used to authenticate. Surely this is obvious? It is certainly obvious to every security-aware organization I have ever worked for, from banks with thousands of branches to my own companies. The client-side code-base 'solution' of trusting all certificates, including self-signed certificates signed by absolutely anybody, or any arbitary body setting itself up as a CA, is ipso facto not secure. It is just playing at security. It is pointless. You are having a private, tamperproof, reply-proof, injection-proof conversation with ... somebody. Anybody. A man in the middle. An impersonator. Anybody. You may as well just use plaintext.

Answer 7

The accepted answer is fine, but I'd like to add something to this as I was using IntelliJ on Mac and couldn't get it to work using the JAVA_HOME path variable.

It turns out Java Home was different when running the application from IntelliJ.

To figure out exactly where it is, you can just do System.getProperty("java.home") as that's where the trusted certificates are read from.

Answer 8

There's a better alternative to trusting all certificates: Create a TrustStore that specifically trusts a given certificate and use this to create a SSLContext from which to get the SSLSocketFactory to set on the HttpsURLConnection. Here's the complete code:

File crtFile = new File("server.crt");
Certificate certificate = CertificateFactory.getInstance("X.509").generateCertificate(new FileInputStream(crtFile));

KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
keyStore.load(null, null);
keyStore.setCertificateEntry("server", certificate);

TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
trustManagerFactory.init(keyStore);

SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, trustManagerFactory.getTrustManagers(), null);

HttpsURLConnection connection = (HttpsURLConnection) new URL(url).openConnection();
connection.setSSLSocketFactory(sslContext.getSocketFactory());

You can alternatively load the KeyStore directly from a file or retrieve the X.509 Certificate from any trusted source.

Note that with this code, the certificates in cacerts will not be used. This particular HttpsURLConnection will only trust this specific certificate.