Storing keys

The Keys and certificates used/generated are stored in a data base called as keystore. By default this database is stored in a file named .keystore.

You can access the contents of this database using the KeyStore class of the java.security package. This manages three different entries namely, PrivateKeyEntry, SecretKeyEntry, TrustedCertificateEntry.

• PrivateKeyEntry
• SecretKeyEntry
• TrustedCertificateEntry

Storing a Key in keystore

In this section, we will learn how to store a key in a keystore. To store a key in the keystore, follow the steps given below.

Step 1: Create a KeyStore object

The getInstance() method of the KeyStore class of the java.security package accepts a string value representing the type of the keystore and returns a KeyStore object.

Create an object of the KeyStore class using the getInstance() method as shown below.

//Creating the KeyStore object
KeyStore keyStore = KeyStore.getInstance("JCEKS");

Step 2: Load the KeyStore object

The load() method of the KeyStore class accepts a FileInputStream object representing the keystore file and a String parameter specifying the password of the KeyStore.

In general, the KeyStore is stored in the file named cacerts, in the location C:/Program Files/Java/jre1.8.0_101/lib/security/ and its default password is changeit, load it using the load() method as shown below.

//Loading the KeyStore object
char[] password = "changeit".toCharArray();
String path = "C:/Program Files/Java/jre1.8.0_101/lib/security/cacerts";
java.io.FileInputStream fis = new FileInputStream(path);
keyStore.load(fis, password);

Step 3: Create the KeyStore.ProtectionParameter object

Instantiate the KeyStore.ProtectionParameter as shown below.

//Creating the KeyStore.ProtectionParameter object
KeyStore.ProtectionParameter protectionParam = new KeyStore.PasswordProtection(password);

Step 4: Create a SecretKey object

Create the SecretKey (interface) object by instantiating its Sub class SecretKeySpec. While instantiating you need to pass password and algorithm as parameters to its constructor as shown below.

//Creating SecretKey object
SecretKey mySecretKey = new SecretKeySpec(new String(keyPassword).getBytes(), "DSA");

Step 5: Create a SecretKeyEntry object

Create an object of the SecretKeyEntry class by passing the SecretKey object created in the above step as shown below.

//Creating SecretKeyEntry object
KeyStore.SecretKeyEntry secretKeyEntry = new KeyStore.SecretKeyEntry(mySecretKey);

Step 6: Set an entry to the KeyStore

The setEntry() method of the KeyStore class accepts a String parameter representing the keystore entry alias, a SecretKeyEntry object, a ProtectionParameter object and, stores the entry under the given alias.

Set the entry to the keystore using the setEntry() method as shown below.

//Set the entry to the keystore
keyStore.setEntry("secretKeyAlias", secretKeyEntry, protectionParam);

Example

The following example stores keys into the keystore existing in the “cacerts” file (windows 10 operating system).

import java.io.FileInputStream;
import java.security.KeyStore;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class StoringIntoKeyStore{
   public static void main(String args[]) throws Exception {
  //Creating the KeyStore object
  KeyStore keyStore = KeyStore.getInstance("JCEKS");
  //Loading the KeyStore object
  char[] password = "changeit".toCharArray();
  String path = "C:/Program Files/Java/jre1.8.0_101/lib/security/cacerts";
  java.io.FileInputStream fis = new FileInputStream(path);
  keyStore.load(fis, password);
  
  //Creating the KeyStore.ProtectionParameter object
  KeyStore.ProtectionParameter protectionParam = new KeyStore.PasswordProtection(password);
  //Creating SecretKey object
  SecretKey mySecretKey = new SecretKeySpec("myPassword".getBytes(), "DSA");
  
  //Creating SecretKeyEntry object
  KeyStore.SecretKeyEntry secretKeyEntry = new KeyStore.SecretKeyEntry(mySecretKey);
  keyStore.setEntry("secretKeyAlias", secretKeyEntry, protectionParam);
  //Storing the KeyStore object
  java.io.FileOutputStream fos = null;
  fos = new java.io.FileOutputStream("newKeyStoreName");
  keyStore.store(fos, password);
  System.out.println("data stored");
   }
}

Output

The above program generates the following output −

System.out.println("data stored");