Does Java support Let's Encrypt certificates?
[Update 2016-06-08: According to https://bugs.openjdk.java.net/browse/JDK-8154757 the IdenTrust CA will be included in Oracle Java 8u101.]
[Update 2016-08-05: Java 8u101 has been released and does indeed include the IdenTrust CA: release notes]
Does Java support Let's Encrypt certificates?
Yes. The Let's Encrypt certificate is just a regular public key certificate. Java supports it (according to Let's Encrypt Certificate Compatibility, for Java 7 >= 7u111 and Java 8 >= 8u101).
Does Java trust Let's Encrypt certificates out of the box?
No / it depends on the JVM. The truststore of Oracle JDK/JRE up to 8u66 contains neither the Let's Encrypt CA specifically nor the IdenTrust CA that cross signed it. new URL("https://letsencrypt.org/").openConnection().connect(); for example results in javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException.
You can however provide your own validator / define a custom keystore that contains the required root CA or import the certificate into the JVM truststore.
https://community.letsencrypt.org/t/will-the-cross-root-cover-trust-by-the-default-list-in-the-jdk-jre/134/10 discusses the topic as well.
Here is some example code that shows how to add a certificate to the default truststore at runtime. You'll just need to add the certificate (exported from firefox as .der and put in classpath)
Based on How can I get a list of trusted root certificates in Java? and http://developer.android.com/training/articles/security-ssl.html#UnknownCa
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.KeyStore;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.PKIXParameters;
import java.security.cert.TrustAnchor;
import java.security.cert.X509Certificate;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLHandshakeException;
import javax.net.ssl.TrustManagerFactory;
public class SSLExample {
// BEGIN ------- ADDME
static {
try {
KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
Path ksPath = Paths.get(System.getProperty("java.home"),
"lib", "security", "cacerts");
keyStore.load(Files.newInputStream(ksPath),
"changeit".toCharArray());
CertificateFactory cf = CertificateFactory.getInstance("X.509");
try (InputStream caInput = new BufferedInputStream(
// this files is shipped with the application
SSLExample.class.getResourceAsStream("DSTRootCAX3.der"))) {
Certificate crt = cf.generateCertificate(caInput);
System.out.println("Added Cert for " + ((X509Certificate) crt)
.getSubjectDN());
keyStore.setCertificateEntry("DSTRootCAX3", crt);
}
if (false) { // enable to see
System.out.println("Truststore now trusting: ");
PKIXParameters params = new PKIXParameters(keyStore);
params.getTrustAnchors().stream()
.map(TrustAnchor::getTrustedCert)
.map(X509Certificate::getSubjectDN)
.forEach(System.out::println);
System.out.println();
}
TrustManagerFactory tmf = TrustManagerFactory
.getInstance(TrustManagerFactory.getDefaultAlgorithm());
tmf.init(keyStore);
SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, tmf.getTrustManagers(), null);
SSLContext.setDefault(sslContext);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
// END ---------- ADDME
public static void main(String[] args) throws IOException {
// signed by default trusted CAs.
testUrl(new URL("https://google.com"));
testUrl(new URL("https://www.thawte.com"));
// signed by letsencrypt
testUrl(new URL("https://helloworld.letsencrypt.org"));
// signed by LE's cross-sign CA
testUrl(new URL("https://letsencrypt.org"));
// expired
testUrl(new URL("https://tv.eurosport.com/"));
// self-signed
testUrl(new URL("https://www.pcwebshop.co.uk/"));
}
static void testUrl(URL url) throws IOException {
URLConnection connection = url.openConnection();
try {
connection.connect();
System.out.println("Headers of " + url + " => "
+ connection.getHeaderFields());
} catch (SSLHandshakeException e) {
System.out.println("Untrusted: " + url);
}
}
}
I know the OP asked for a solution without local configuration changes, but in case you want to add the trust chain to the keystore permanently:
$ keytool -trustcacerts \
-keystore $JAVA_HOME/jre/lib/security/cacerts \
-storepass changeit \
-noprompt \
-importcert \
-file /etc/letsencrypt/live/hostname.com/chain.pem
source: https://community.letsencrypt.org/t/will-the-cross-root-cover-trust-by-the-default-list-in-the-jdk-jre/134/13
Detailed answer for those of us willing to make local config changes that includes backing up the config file:
1. Test if it is working before the changes
If you don't have a test program already, you can use my java SSLPing ping program which tests the TLS handshake (will work with any SSL/TLS port, not just HTTPS). I'll use the prebuilt SSLPing.jar, but reading the code and building it yourself is a quick and easy task:
$ git clone https://github.com/dimalinux/SSLPing.git
Cloning into 'SSLPing'...
[... output snipped ...]
Since my Java version is earlier than 1.8.0_101 (not released at the time of this writing), a Let's Encrypt certificate will not verify by default. Let's see what failure looks like before applying the fix:
$ java -jar SSLPing/dist/SSLPing.jar helloworld.letsencrypt.org 443
About to connect to 'helloworld.letsencrypt.org' on port 443
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
[... output snipped ...]
2. Import the certificate
I'm on Mac OS X with the JAVA_HOME environment variable set. Later commands will assume this variable is set for the java installation you are modifying:
$ echo $JAVA_HOME
/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home/
Make a backup of the cacerts file we will be modifying so you can back out any change without reinstalling the JDK:
$ sudo cp -a $JAVA_HOME/jre/lib/security/cacerts $JAVA_HOME/jre/lib/security/cacerts.orig
Download the signing certificate we need to import:
$ wget https://letsencrypt.org/certs/lets-encrypt-x3-cross-signed.der
Perform the import:
$ sudo keytool -trustcacerts -keystore $JAVA_HOME/jre/lib/security/cacerts -storepass changeit -noprompt -importcert -alias lets-encrypt-x3-cross-signed -file lets-encrypt-x3-cross-signed.der
Certificate was added to keystore
3. Verify that it is working after the changes
Verify that Java is now happy connecting to the SSL port:
$ java -jar SSLPing/dist/SSLPing.jar helloworld.letsencrypt.org 443
About to connect to 'helloworld.letsencrypt.org' on port 443
Successfully connected