Import PEM into Java Key Store

Question

First, convert your certificate in a DER format :

openssl x509 -outform der -in certificate.pem -out certificate.der

And after, import it in the keystore :

keytool -import -alias your-alias -keystore cacerts -file certificate.der

If you only want to import a certificate in PEM format into a keystore, keytool will do the job:

keytool -import -alias *alias* -keystore cacerts -file *cert.pem*

I've developed http://code.google.com/p/java-keyutil/ which imports PEM certificates straight into a Java keystore. Its primary purpose is to import a multi-part PEM Operating System certificate bundles such as ca-bundle.crt. These often includes headers which keytool cannot handle

</self promotion>

In my case I had a pem file which contained two certificates and an encrypted private key to be used in mutual SSL authentication. So my pem file looked like this:

-----BEGIN CERTIFICATE-----

...

-----END CERTIFICATE-----

-----BEGIN RSA PRIVATE KEY-----

Proc-Type: 4,ENCRYPTED

DEK-Info: DES-EDE3-CBC,C8BF220FC76AA5F9

...

-----END RSA PRIVATE KEY-----

-----BEGIN CERTIFICATE-----

...

-----END CERTIFICATE-----

Here is what I did

Split the file into three separate files, so that each one contains just one entry, starting with ---BEGIN.. and ending with ---END.. lines. Lets assume we now have three files: cert1.pem, cert2.pem, and pkey.pem.

Convert pkey.pem into DER format using openssl and the following syntax:

openssl pkcs8 -topk8 -nocrypt -in pkey.pem -inform PEM -out pkey.der -outform DER

Note, that if the private key is encrypted you need to supply a password( obtain it from the supplier of the original pem file ) to convert to DER format, openssl will ask you for the password like this: "enter a passphrase for pkey.pem: ".

If conversion is successful, you will get a new file called pkey.der.

Create a new java keystore and import the private key and the certificates:

String keypass = "password";  // this is a new password, you need to come up with to protect your java key store file
String defaultalias = "importkey";
KeyStore ks = KeyStore.getInstance("JKS", "SUN");

// this section does not make much sense to me, 
// but I will leave it intact as this is how it was in the original example I found on internet:   
ks.load( null, keypass.toCharArray());
ks.store( new FileOutputStream ( "mykeystore"  ), keypass.toCharArray());
ks.load( new FileInputStream ( "mykeystore" ),    keypass.toCharArray());
// end of section..


// read the key file from disk and create a PrivateKey

FileInputStream fis = new FileInputStream("pkey.der");
DataInputStream dis = new DataInputStream(fis);
byte[] bytes = new byte[dis.available()];
dis.readFully(bytes);
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);

byte[] key = new byte[bais.available()];
KeyFactory kf = KeyFactory.getInstance("RSA");
bais.read(key, 0, bais.available());
bais.close();

PKCS8EncodedKeySpec keysp = new PKCS8EncodedKeySpec ( key );
PrivateKey ff = kf.generatePrivate (keysp);


// read the certificates from the files and load them into the key store:

Collection  col_crt1 = CertificateFactory.getInstance("X509").generateCertificates(new FileInputStream("cert1.pem"));
Collection  col_crt2 = CertificateFactory.getInstance("X509").generateCertificates(new FileInputStream("cert2.pem"));

Certificate crt1 = (Certificate) col_crt1.iterator().next();
Certificate crt2 = (Certificate) col_crt2.iterator().next();
Certificate[] chain = new Certificate[] { crt1, crt2 };

String alias1 = ((X509Certificate) crt1).getSubjectX500Principal().getName();
String alias2 = ((X509Certificate) crt2).getSubjectX500Principal().getName();

ks.setCertificateEntry(alias1, crt1);
ks.setCertificateEntry(alias2, crt2);

// store the private key
ks.setKeyEntry(defaultalias, ff, keypass.toCharArray(), chain );

// save the key store to a file         
ks.store(new FileOutputStream ( "mykeystore" ),keypass.toCharArray());

(optional) Verify the content of your new key store:

$ keytool -list -keystore mykeystore -storepass password

Keystore type: JKS Keystore provider: SUN

Your keystore contains 3 entries:

• cn=...,ou=...,o=.., Sep 2, 2014, trustedCertEntry, Certificate fingerprint (SHA1): 2C:B8: ...

• importkey, Sep 2, 2014, PrivateKeyEntry, Certificate fingerprint (SHA1): 9C:B0: ...

• cn=...,o=...., Sep 2, 2014, trustedCertEntry, Certificate fingerprint (SHA1): 83:63: ...

(optional) Test your certificates and private key from your new key store against your SSL server: ( You may want to enable debugging as an VM option: -Djavax.net.debug=all )

        char[] passw = "password".toCharArray();
        KeyStore ks = KeyStore.getInstance("JKS", "SUN");
        ks.load(new FileInputStream ( "mykeystore" ), passw );

        KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
        kmf.init(ks, passw);

        TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        tmf.init(ks);
        TrustManager[] tm = tmf.getTrustManagers();

        SSLContext sclx = SSLContext.getInstance("TLS");
        sclx.init( kmf.getKeyManagers(), tm, null);

        SSLSocketFactory factory = sclx.getSocketFactory();
        SSLSocket socket = (SSLSocket) factory.createSocket( "192.168.1.111", 443 );
        socket.startHandshake();

        //if no exceptions are thrown in the startHandshake method, then everything is fine..

Finally register your certificates with HttpsURLConnection if plan to use it:

        char[] passw = "password".toCharArray();
        KeyStore ks = KeyStore.getInstance("JKS", "SUN");
        ks.load(new FileInputStream ( "mykeystore" ), passw );

        KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
        kmf.init(ks, passw);

        TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        tmf.init(ks);
        TrustManager[] tm = tmf.getTrustManagers();

        SSLContext sclx = SSLContext.getInstance("TLS");
        sclx.init( kmf.getKeyManagers(), tm, null);

        HostnameVerifier hv = new HostnameVerifier()
        {
            public boolean verify(String urlHostName, SSLSession session)
            {
                if (!urlHostName.equalsIgnoreCase(session.getPeerHost()))
                {
                    System.out.println("Warning: URL host '" + urlHostName + "' is different to SSLSession host '" + session.getPeerHost() + "'.");
                }
                return true;
            }
        };

        HttpsURLConnection.setDefaultSSLSocketFactory( sclx.getSocketFactory() );
        HttpsURLConnection.setDefaultHostnameVerifier(hv);

If you need an easy way to load PEM files in Java without having to deal with external tools (opensll, keytool), here is my code I use in production :

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.security.KeyFactory;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.security.interfaces.RSAPrivateKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.ArrayList;
import java.util.List;

import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLServerSocketFactory;
import javax.xml.bind.DatatypeConverter;

public class PEMImporter {

    public static SSLServerSocketFactory createSSLFactory(File privateKeyPem, File certificatePem, String password) throws Exception {
        final SSLContext context = SSLContext.getInstance("TLS");
        final KeyStore keystore = createKeyStore(privateKeyPem, certificatePem, password);
        final KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
        kmf.init(keystore, password.toCharArray());
        final KeyManager[] km = kmf.getKeyManagers();
        context.init(km, null, null);
        return context.getServerSocketFactory();
    }

    /**
     * Create a KeyStore from standard PEM files
     * 
     * @param privateKeyPem the private key PEM file
     * @param certificatePem the certificate(s) PEM file
     * @param the password to set to protect the private key
     */
    public static KeyStore createKeyStore(File privateKeyPem, File certificatePem, final String password)
            throws Exception, KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
        final X509Certificate[] cert = createCertificates(certificatePem);
        final KeyStore keystore = KeyStore.getInstance("JKS");
        keystore.load(null);
        // Import private key
        final PrivateKey key = createPrivateKey(privateKeyPem);
        keystore.setKeyEntry(privateKeyPem.getName(), key, password.toCharArray(), cert);
        return keystore;
    }

    private static PrivateKey createPrivateKey(File privateKeyPem) throws Exception {
        final BufferedReader r = new BufferedReader(new FileReader(privateKeyPem));
        String s = r.readLine();
        if (s == null || !s.contains("BEGIN PRIVATE KEY")) {
            r.close();
            throw new IllegalArgumentException("No PRIVATE KEY found");
        }
        final StringBuilder b = new StringBuilder();
        s = "";
        while (s != null) {
            if (s.contains("END PRIVATE KEY")) {
                break;
            }
            b.append(s);
            s = r.readLine();
        }
        r.close();
        final String hexString = b.toString();
        final byte[] bytes = DatatypeConverter.parseBase64Binary(hexString);
        return generatePrivateKeyFromDER(bytes);
    }

    private static X509Certificate[] createCertificates(File certificatePem) throws Exception {
        final List<X509Certificate> result = new ArrayList<X509Certificate>();
        final BufferedReader r = new BufferedReader(new FileReader(certificatePem));
        String s = r.readLine();
        if (s == null || !s.contains("BEGIN CERTIFICATE")) {
            r.close();
            throw new IllegalArgumentException("No CERTIFICATE found");
        }
        StringBuilder b = new StringBuilder();
        while (s != null) {
            if (s.contains("END CERTIFICATE")) {
                String hexString = b.toString();
                final byte[] bytes = DatatypeConverter.parseBase64Binary(hexString);
                X509Certificate cert = generateCertificateFromDER(bytes);
                result.add(cert);
                b = new StringBuilder();
            } else {
                if (!s.startsWith("----")) {
                    b.append(s);
                }
            }
            s = r.readLine();
        }
        r.close();

        return result.toArray(new X509Certificate[result.size()]);
    }

    private static RSAPrivateKey generatePrivateKeyFromDER(byte[] keyBytes) throws InvalidKeySpecException, NoSuchAlgorithmException {
        final PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        final KeyFactory factory = KeyFactory.getInstance("RSA");
        return (RSAPrivateKey) factory.generatePrivate(spec);
    }

    private static X509Certificate generateCertificateFromDER(byte[] certBytes) throws CertificateException {
        final CertificateFactory factory = CertificateFactory.getInstance("X.509");
        return (X509Certificate) factory.generateCertificate(new ByteArrayInputStream(certBytes));
    }

}

Have fun.