SHA-256 Hash in Java

 Hello Guys,

    In Cryptography, SHA is cryptographic hash function which takes input as 20 Bytes and rendered the hash value in hexadecimal number, 40 digits long approx.

Message Digest Class :

• To calculate cryptographic hashing value in Java, MessageDigest Class is used, under the package java.security.

• MessageDigest Class provides following cryptographic hash function to find hash value of a text, they are:

                  MD5

                  SHA-1

                  SHA-256

This Algorithms are initialized in static method called getInstance(). After selecting the algorithm it calculate the digest value and return the results in byte array.

BigInteger Class : 

• BigInteger is used, which converts the resultant byte array into its sign-magnitude representation. This representation is converted into hex format to get the MessageDigest. 

SHA-256 PROGRAM

import java.io.*;

import java.util.*;

import java.math.BigInteger;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

class SHA256

{

   public static String getSHA256(String s)

   {

    try{  

        MessageDigest md = MessageDigest.getInstance("SHA-256");

      

       byte [] messageDigest = md.digest(s.getBytes());

      

       BigInteger no = new BigInteger(1,messageDigest);

      

       String hash = no.toString(16);

      

       while(hash.length() < 32)

       {

          hash = "0" + hash;

       }

        return hash;

     }  

      catch(NoSuchAlgorithmException e)

      {

         throw new RuntimeException(e);

      }

}

public static void main(String [] args)

{

    System.out.print("Enter the word :");  

    Scanner scan = new Scanner(System.in);

    String s = scan.next();

    System.out.println(s+ " : "+getSHA256(s));

}

}   

Output :

Enter the word :Hello

Hello : 185f8db32271fe25f561a6fc938b2e264306ec304eda518007d1764826381969

Enter the word :infopsh

infopsh : f3d96df7c3b21c554b5be9198b6ad27a2f49c25ad6c5709d30faef27c54d8044

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