Java Tutorial/Security/Keystore

Adding a Certificate to a Key Store

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.Key;
import java.security.KeyStore;
import java.security.cert.Certificate;
public class Main {
  public static void main(String[] argv) throws Exception {
    FileInputStream is = new FileInputStream("your.keystore");
    KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
    keystore.load(is, "my-keystore-password".toCharArray());
    String alias = "myalias";
    char[] password = "password".toCharArray();
    Certificate cert = keystore.getCertificate(alias);
    File keystoreFile = new File("your.keystore");
    // Load the keystore contents
    FileInputStream in = new FileInputStream(keystoreFile);
    keystore.load(in, password);
    in.close();
    // Add the certificate
    keystore.setCertificateEntry(alias, cert);
    // Save the new keystore contents
    FileOutputStream out = new FileOutputStream(keystoreFile);
    keystore.store(out, password);
    out.close();
  }
}

Create a keystore with a self-signed certificate, using the keytool command

keytool -keystore mySrvKeystore -keypasswd 123456 -genkey -keyalg RSA -alias mycert

Listing the Aliases in a Key Store: A key store is a collection of keys and certificates.

import java.io.FileInputStream;
import java.security.KeyStore;
import java.util.Enumeration;
public class Main {
  public static void main(String[] argv) throws Exception {
    FileInputStream is = new FileInputStream("yourfile"+".keystore");
    KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
    String password = "my-keystore-password";
    keystore.load(is, password.toCharArray());
    Enumeration e = keystore.aliases();
    for (; e.hasMoreElements();) {
      String alias = (String) e.nextElement();
      boolean b = keystore.isKeyEntry(alias);
      b = keystore.isCertificateEntry(alias);
    }
    is.close();
  }
}

Listing the Aliases in a Key Store using keytool:

keytool -list -storepass my-keystore-password

Retrieving a Certificate from a Key Store

import java.io.FileInputStream;
import java.security.KeyStore;
public class Main {
  public static void main(String[] argv) throws Exception {
    FileInputStream is = new FileInputStream("your.keystore");
    KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
    keystore.load(is, "my-keystore-password".toCharArray());
    // Get certificate
    java.security.cert.Certificate cert = keystore.getCertificate("myalias");
  }
}

Retrieving a Key Pair from a Key Store

import java.io.FileInputStream;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.cert.Certificate;
public class Main {
  public static void main(String[] argv) throws Exception {
    FileInputStream is = new FileInputStream("your.keystore");
    KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
    keystore.load(is, "my-keystore-password".toCharArray());
    String alias = "myalias";
    Key key = keystore.getKey(alias, "password".toCharArray());
    if (key instanceof PrivateKey) {
      // Get certificate of public key
      Certificate cert = keystore.getCertificate(alias);
      // Get public key
      PublicKey publicKey = cert.getPublicKey();
      // Return a key pair
      new KeyPair(publicKey, (PrivateKey) key);
    }
  }
}

Specify the keystore of certificates using the javax.net.ssl.keyStore system property:

java -Djavax.net.ssl.keyStore=mySrvKeystore -Djavax.net.ssl.keyStorePassword=123456 MyServer