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 : d9cce882ee690a5c1ce70beff3a78c77Input : 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( "\n" + s1 + " : " + encryptThisString(s1));
String s2 = "hello world" ;
System.out.println( "\n" + s2 + " : " + encryptThisString(s2));
}
} |
Output:
HashCode Generated by MD2 for: GeeksForGeeks : 787df774a3d25dca997b1f1c8bfee4af hello world : d9cce882ee690a5c1ce70beff3a78c77
Application:
- Cryptography
- Data Integrity