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MD5 hash in Java

  • Difficulty Level : Easy
  • Last Updated : 05 Aug, 2020

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:
1. MD5
2. SHA-1
3. SHA-256

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

BigInteger class is used, which converts the resultant byte array into its sign-magnitude representation.

This representation converts into hex format to get the MessageDigest



Examples:

Input : hello world
Output : 5eb63bbbe01eeed093cb22bb8f5acdc3

Input : GeeksForGeeks
Output : e39b9c178b2c9be4e99b141d956c6ff6




import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
  
// Java program to calculate MD5 hash value
public class MD5 {
    public static String getMd5(String input)
    {
        try {
  
            // Static getInstance method is called with hashing MD5
            MessageDigest md = MessageDigest.getInstance("MD5");
  
            // digest() method is called to calculate message digest
            //  of an input digest() return array of byte
            byte[] messageDigest = md.digest(input.getBytes());
  
            // Convert byte array into signum representation
            BigInteger no = new BigInteger(1, messageDigest);
  
            // Convert message digest into hex value
            String hashtext = no.toString(16);
            while (hashtext.length() < 32) {
                hashtext = "0" + hashtext;
            }
            return hashtext;
        
  
        // For specifying wrong message digest algorithms
        catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }
  
    // Driver code
    public static void main(String args[]) throws NoSuchAlgorithmException
    {
        String s = "GeeksForGeeks";
        System.out.println("Your HashCode Generated by MD5 is: " + getMd5(s));
    }
}

Output:

Your HashCode Generated by MD5 is: e39b9c178b2c9be4e99b141d956c6ff6

References: Java Docs for MessageDigest

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