MD2 Hash In Java

The MD2 is a Message-Digest Algorithm. It is a cryptographic hash function developed by Ronald Rivest in 1989. It is optimized for 8-bit computers. The MD2 algorithm is used in public key infrastructures as part of certificates generated with MD2 and RSA. From 2014, this algorithm is now not considered as a secure algorithm.

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

MessagDigest Class provides following cryptographic hash function to find hash value of a text as follows:

MD2
MD5
SHA-1
SHA-224
SHA-256
SHA-384
SHA-512

These algorithms are initialized in static method called getInstance(). After selecting the algorithm the message digest value is calculated and the results are returned as a byte array. BigInteger class is used, to convert the resultant byte array into its signum representation. This representation is then converted into a hexadecimal format to get the expected MessageDigest.

Examples:

Input : hello world
Output : d9cce882ee690a5c1ce70beff3a78c77

Input : GeeksForGeeks
Output : 787df774a3d25dca997b1f1c8bfee4af

Below program shows the implementation of MD2 hash in Java.

// Java program to calculate MD2 hash value 
  
import java.math.BigInteger; 
import java.security.MessageDigest; 
import java.security.NoSuchAlgorithmException; 
  
public class GFG { 
    public static String encryptThisString(String input) 
    { 
        try { 
            // getInstance() method is called with algorithm MD2 
            MessageDigest md = MessageDigest.getInstance("MD2"); 
  
            // digest() method is called 
            // to calculate message digest of the input string 
            // returned as 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); 
  
            // Add preceding 0s to make it 32 bit 
            while (hashtext.length() < 32) { 
                hashtext = "0" + hashtext; 
            } 
  
            // return the 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 
    { 
        System.out.println("HashCode Generated by MD2 for: "); 
  
        String s1 = "GeeksForGeeks"; 
        System.out.println("
" + s1 + " : " + encryptThisString(s1)); 
  
        String s2 = "hello world"; 
        System.out.println("
" + s2 + " : " + encryptThisString(s2)); 
    } 
} 

Output:

HashCode Generated by MD2 for: 

GeeksForGeeks : 787df774a3d25dca997b1f1c8bfee4af

hello world : d9cce882ee690a5c1ce70beff3a78c77

Application:

Cryptography
Data Integrity

tags:

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