SecureRandom setSeed() method in Java with Examples
The setSeed() method of java.security.SecureRandom class is used to reseeds this random object. The given seed supplements, rather than replaces, the existing seed. Thus, repeated calls are guaranteed never to reduce randomness.
Syntax:
public void setSeed(byte[] seed)
Parameters: This method takes the seed as a parameter.
Note: Every time Secure Random class will generate random output
Below are the examples to illustrate the setSeed() method:
Example 1:
// Java program to demonstrate // setSeed() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) { try { // creating the object of SecureRandom SecureRandom sr = SecureRandom.getInstance( "SHA1PRNG" ); // Declaring the string variable String str = "Tajmahal" ; // Declaring the byte Array b byte [] b = str.getBytes(); // Reseeding the random object sr.setSeed(b); // getting the seeds byte [] seeds = sr.getSeed( 10 ); // printing the seed serialwise for ( int i = 0 ; i < seeds.length; i++) System.out.println( "Seed[" + i + "] : " + seeds[i]); } catch (NoSuchAlgorithmException e) { System.out.println( "Exception thrown : " + e); } catch (ProviderException e) { System.out.println( "Exception thrown : " + e); } } } |
Output:
Seed[0]:69 Seed[0] : 23 Seed[1] : -99 Seed[2] : -51 Seed[3] : 107 Seed[4] : 41 Seed[5] : -96 Seed[6] : -93 Seed[7] : -86 Seed[8] : 127 Seed[9] : 47
Example 2:
// Java program to demonstrate // setSeed() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) { try { // creating the object of SecureRandom SecureRandom sr = new SecureRandom( new byte [] { 1 , 2 , 3 , 4 }); // Declaring the string variable String str = "Tajmahal" ; // Declaring the byte Array b byte [] b = str.getBytes(); // Reseeding the random object sr.setSeed(b); // getting the seeds byte [] seeds = sr.getSeed( 10 ); // printing the seed serialwise for ( int i = 0 ; i < seeds.length; i++) System.out.println( "Seed[" + i + "]:" + seeds[i]); } catch (ProviderException e) { System.out.println( "Exception thrown : " + e); } } } |
Output:
Seed[0]:92 Seed[1]:127 Seed[2]:28 Seed[3]:-127 Seed[4]:-100 Seed[5]:-110 Seed[6]:86 Seed[7]:-55 Seed[8]:48 Seed[9]:-78
The setSeed(long seed) method of java.security.SecureRandom class is used to reseeds this random object, using the eight bytes contained in the given long seed. The given seed supplements, rather than replaces, the existing seed. Thus, repeated calls are guaranteed never to reduce randomness.
Syntax:
public void setSeed( long seed )
Parameters: This method takes the seed as a parameter
Note: Every time Secure Random class will generate random output
Below are the examples to illustrate the setSeed() method:
Example 1:
// Java program to demonstrate // setSeed() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { // creating the object of SecureRandom SecureRandom sr = SecureRandom.getInstance( "SHA1PRNG" , "SUN" ); // Reseeding the random object sr.setSeed(101L); // getting the seeds byte [] seeds = sr.getSeed( 10 ); // printing the seed serialwise for ( int i = 0 ; i < seeds.length; i++) System.out.println( "Seed[" + i + "] : " + seeds[i]); } catch (NoSuchAlgorithmException e) { System.out.println( "Exception thrown : " + e); } catch (ProviderException e) { System.out.println( "Exception thrown : " + e); } } } |
Output:
Seed[0] : -36 Seed[1] : -65 Seed[2] : -94 Seed[3] : 16 Seed[4] : -104
Example 2:
// Java program to demonstrate // setSeed() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) { try { // creating the object of SecureRandom SecureRandom sr = new SecureRandom( new byte [] { 1 , 2 , 3 , 4 }); // Reseeding the random object sr.setSeed(101L); // getting the seeds byte [] seeds = sr.getSeed( 10 ); // printing the seed serialwise for ( int i = 0 ; i < seeds.length; i++) System.out.println( "Seed[" + i + "]:" + seeds[i]); } catch (ProviderException e) { System.out.println( "Exception thrown : " + e); } } } |
Output:
Seed[0]:-29 Seed[1]:-93 Seed[2]:6 Seed[3]:66 Seed[4]:126 Seed[5]:93 Seed[6]:-58 Seed[7]:-91 Seed[8]:-62 Seed[9]:-58