KeyPairGenerator genKeyPair() method in Java with Examples

The genKeyPair() method of java.security.KeyPairGenerator class is used to generate a key pair.
If this KeyPairGenerator has not been initialized explicitly, provider-specific defaults will be used for the size and other (algorithm-specific) values of the generated keys.

This will generate a new key pair every time it is called.

Syntax:

public final KeyPair genKeyPair()

Return Value: This method returns the generated key pair

Below are the examples to illustrate the genKeyPair() method

Note: These programs wont run in online IDE.

Example 1: With initialization  

Java

// Java program to demonstrate
// genKeyPair() method

import java.security.*;
import java.util.*;

public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {

            // creating the object of KeyPairGenerator
            KeyPairGenerator kpg = KeyPairGenerator
                                       .getInstance("RSA");

            // initializing with 1024
            kpg.initialize(1024);

            // getting key pairs
            // using genKeyPair() method
            KeyPair kp = kpg.genKeyPair();

            // printing the Keypair
            System.out.println("Keypair : " + kp);
        }

        catch (NoSuchAlgorithmException e) {

            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Keypair : java.security.KeyPair@12a3a380

Example 2: Without Initialization

Java

// Java program to demonstrate
// genKeyPair() method

import java.security.*;
import java.util.*;

public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {

            // creating the object of KeyPairGenerator
            KeyPairGenerator kpg = KeyPairGenerator
                                       .getInstance("RSA");

            // getting key pairs
            // using genKeyPair() method
            KeyPair kp = kpg.genKeyPair();

            // printing the number of byte
            System.out.println("Keypair : " + kp);
        }

        catch (NoSuchAlgorithmException e) {

            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Keypair : java.security.KeyPair@12a3a380