KeyPairGenerator initialize() method in Java with Examples
initialize(int keysize)
The initialize() method of java.security.KeyPairGenerator is used to initialize KeyPairGenerator object for further use.
Syntax:
public void initialize(int keysize)
Parameters: This method seeks keysize of int type as a parameter.
Return Value: This method has nothing to return.
Exception: This method throws InvalidParameterException if the greater or lesser value than the specified criteria is passed.
Note: The following program will not run on the online IDE.
Below are the examples to illustrate the initialize(int keysize) method:
Example 1:
Java
// Java program to demonstrate// initialize() methodimport java.security.*;import java.util.*;public class GFG { 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); } }} |
Keypair : java.security.KeyPair@12a3a380
Example 2: For InvalidParameterException
Java
// Java program to demonstrate// initialize() methodimport java.security.*;import java.util.*;public class GFG { public static void main(String[] argv) throws Exception { try { // creating the object of KeyPairGenerator KeyPairGenerator kpg = KeyPairGenerator .getInstance("RSA"); // initializing with 1024 kpg.initialize(-24); // 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); } catch (InvalidParameterException e) { System.out.println("Exception thrown : " + e); } }} |
Exception thrown : java.security.InvalidParameterException: RSA keys must be at least 512 bits long
initialize(int keysize, SecureRandom random)
The initialize() method of java.security.KeyPairGenerator initializes KeyPairGenerator for particular size with SecureRandom object to use further.
Syntax:
public void initialize(int keysize,
SecureRandom random)
Parameters: This method takes the following arguments as parameters:
- size: which is the keysize
- random: which is the object of SecureRandom type
Return Value: This method provides the object of KeyPairGenerator.
Exception: This method throws InvalidParameterException if the greater or lesser value than the specified criteria is passed.
Below are the examples to illustrate the initialize() method:
Example 1:
Java
// Java program to demonstrate// initialize() methodimport java.security.*;import java.util.*;public class GFG { public static void main(String[] argv) throws Exception { try { // creating the object of KeyPairGenerator KeyPairGenerator kpg = KeyPairGenerator .getInstance("RSA"); // creating the object of SecureRandom SecureRandom se = SecureRandom.getInstance("SHA1PRNG"); // initializing with 1024 kpg.initialize(1024, se); // 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); } catch (InvalidParameterException e) { System.out.println("Exception thrown : " + e); } }} |
Keypair : java.security.KeyPair@4e25154f
Example 2: For InvalidParameterException
Java
// Java program to demonstrate// initialize() methodimport java.security.*;import java.util.*;public class GFG { public static void main(String[] argv) throws Exception { try { // creating the object of KeyPairGenerator KeyPairGenerator kpg = KeyPairGenerator .getInstance("RSA"); // creating the object of SecureRandom SecureRandom se = SecureRandom.getInstance("SHA1PRNG"); // initializing with -24 kpg.initialize(-24, se); // 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); } catch (InvalidParameterException e) { System.out.println("Exception thrown : " + e); } }} |
Exception thrown : java.security.InvalidParameterException: RSA keys must be at least 512 bits long
