Import PEM into Java Key Store

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.

I used Keystore Explorer

1. Open JKS with a private key
2. Examine signed PEM from CA
3. Import key
4. Save JKS

I'm always forgetting how to do this because it's something that I just do once in a while, this is one possible solution, and it just works:

1. Go to your favourite browser and download the main certificate from the secured website.

2. Execute the two following lines of code:

   $ openssl x509 -outform der -in GlobalSignRootCA.crt -out GlobalSignRootCA.der
   $ keytool -import -alias GlobalSignRootCA -keystore GlobalSignRootCA.jks -file GlobalSignRootCA.der
   

3. If executing in Java SE environment add the following options:

   $ java -Djavax.net.ssl.trustStore=GlobalSignRootCA.jks -Djavax.net.ssl.trustStorePassword=trustStorePassword -jar MyJar.jar
   

4. Or add the following to the java code:

   System.setProperty("javax.net.ssl.trustStore", "GlobalSignRootCA.jks");
   System.setProperty("javax.net.ssl.trustStorePassword","trustStorePassword");
   

The other option for step 2 is to just using the keytool command. Bellow is an example with a chain of certificates:

$ keytool -import -file org.eu.crt -alias orgcrt -keystore globalsignrs.jks
$ keytool -import -file GlobalSignOrganizationValidationCA-SHA256-G2.crt -alias globalsignorgvalca -keystore globalsignrs.jks
$ keytool -import -file GlobalSignRootCA.crt -alias globalsignrootca -keystore globalsignrs.jks

There is also a GUI tool that allows visual JKS creation and certificates importing.

http://portecle.sourceforge.net/

Portecle is a user friendly GUI application for creating, managing and examining keystores, keys, certificates, certificate requests, certificate revocation lists and more.

I got it from internet. It works pretty good for pem files that contains multiple entries.

#!/bin/bash
pemToJks()
{
        # number of certs in the PEM file
        pemCerts=$1
        certPass=$2
        newCert=$(basename "$pemCerts")
        newCert="${newCert%%.*}"
        newCert="${newCert}"".JKS"
        ##echo $newCert $pemCerts $certPass
        CERTS=$(grep 'END CERTIFICATE' $pemCerts| wc -l)
        echo $CERTS
        # For every cert in the PEM file, extract it and import into the JKS keystore
        # awk command: step 1, if line is in the desired cert, print the line
        #              step 2, increment counter when last line of cert is found
        for N in $(seq 0 $(($CERTS - 1))); do
          ALIAS="${pemCerts%.*}-$N"
          cat $pemCerts |
                awk "n==$N { print }; /END CERTIFICATE/ { n++ }" |
                $KEYTOOLCMD -noprompt -import -trustcacerts \
                                -alias $ALIAS -keystore $newCert -storepass $certPass
        done
}
pemToJks <pem to import> <pass for new jks>

Although this question is pretty old and it has already a-lot answers, I think it is worth to provide an alternative. Using native java classes makes it very verbose to just use pem files and almost forces you wanting to convert the pem files into p12 or jks files as using p12 or jks files are much easier. I want to give anyone who wants an alternative for the already provided answers.

GitHub - SSLContext Kickstart

var keyManager = PemUtils.loadIdentityMaterial("certificate-chain.pem", "private-key.pem");
var trustManager = PemUtils.loadTrustMaterial("some-trusted-certificate.pem");

var sslFactory = SSLFactory.builder()
          .withIdentityMaterial(keyManager)
          .withTrustMaterial(trustManager)
          .build();

var sslContext = sslFactory.getSslContext();

I need to provide some disclaimer here, I am the library maintainer

OpenJDK keytool handles PEM certificates natively now (and has been for a few releases but I'm not sure since when).

keytool recommends against specifying the cacerts file path like any other keystore but using -cacerts option instead.

So the command line which works with OpenJDK 18 (and probably many earlier versions) is:

keytool -cacerts -import -alias <alias> -file <path_to_cert.pem>