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

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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