1. Java Cryptography
2. Java Cipher
3. Java MessageDigest
4. Java Mac
5. Java Signature
6. Java KeyGenerator
7. Java KeyPair
8. Java KeyPairGenerator
9. Java KeyStore
10. Java Keytool
11. Java Certificate
12. Java CertificateFactory
13. Java CertPath

• Creating a KeyGenerator Instance
• Initializing the KeyGenerator
• Generating a Key

The Java KeyGenerator class (javax.crypto.KeyGenerator) is used to generate symmetric encryption keys. A symmetric encryption key is a key that is used for both encryption and decryption of data, by a symmetric encryption algorithm. In this Java KeyGenerator tutorial I will show you how to generate symmetric encryption keys.

Creating a KeyGenerator Instance

Before you can use the Java KeyGenerator class you must create a KeyGenerator instance. You create a KeyGenerator instance by calling the static method getInstance() passing as parameter the name of the encryption algorithm to create a key for. Here is an example of creating a Java KeyGenerator instance:

KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");

This example creates a KeyGenerator instance which can generate keys for the AES encryption algorithm.

Initializing the KeyGenerator

After creating the KeyGenerator instance you must initialize it. Initializing a KeyGenerator instance is done by calling its init() method. Here is an example of initializing a KeyGenerator instance:

SecureRandom secureRandom = new SecureRandom();
int keyBitSize = 256;

keyGenerator.init(keyBitSize, secureRandom);

The KeyGenerator init() method takes two parameters: The bit size of the keys to generate, and a SecureRandom that is used during key generation.

Generating a Key

Once the Java KeyGenerator instance is initialized you can use it to generate keys. Generating a key is done by calling the KeyGenerator generateKey() method. Here is an example of generating a symmetric key:

SecretKey secretKey = keyGenerator.generateKey();