How can I generate an MD5 hash in Java?

Question

Is there any method to generate MD5 hash of a string in Java?

koregan_5752 · Answer

The MessageDigest class can provide you with an instance of the MD5 digest.

When working with strings and the crypto classes be sure to always specify the encoding you want the byte representation in. If you just use string.getBytes() it will use the platform default. (Not all platforms use the same defaults)

import java.security.*;

..

byte[] bytesOfMessage = yourString.getBytes("UTF-8");

MessageDigest md = MessageDigest.getInstance("MD5");
byte[] theMD5digest = md.digest(bytesOfMessage);

If you have a lot of data take a look at the .update(xxx) methods which can be called repeatedly. Then call .digest() to obtain the resulting hash.

user_43582 · Answer

You need java.security.MessageDigest.

Call MessageDigest.getInstance("MD5") to get a MD5 instance of MessageDigest you can use.

The compute the hash by doing one of:

Feed the entire input as a byte[] and calculate the hash in one operation with md.digest(bytes).
Feed the MessageDigest one byte[] chunk at a time by calling md.update(bytes). When you're done adding input bytes, calculate the hash with md.digest().

The byte[] returned by md.digest() is the MD5 hash.

user_49913 · Answer

If you actually want the answer back as a string as opposed to a byte array, you could always do something like this:

String plaintext = "your text here";
MessageDigest m = MessageDigest.getInstance("MD5");
m.reset();
m.update(plaintext.getBytes());
byte[] digest = m.digest();
BigInteger bigInt = new BigInteger(1,digest);
String hashtext = bigInt.toString(16);
// Now we need to zero pad it if you actually want the full 32 chars.
while(hashtext.length() < 32 ){
  hashtext = "0"+hashtext;
}

lutzh_52055 · Answer

You might also want to look at the DigestUtils class of the apache commons codec project, which provides very convenient methods to create MD5 or SHA digests.

user_42404 · Answer

Bombe's answer is correct, however note that unless you absolutely must use MD5 (e.g. forced on you for interoperability), a better choice is SHA1 as MD5 has weaknesses for long term use.

I should add that SHA1 also has theoretical vulnerabilities, but not as severe. The current state of the art in hashing is that there are a number of candidate replacement hash functions but none have yet emerged as the standard best practice to replace SHA1. So, depending on your needs you would be well advised to make your hash algorithm configurable so it can be replaced in future.

user_836967 · Answer

import java.security.*;
import javax.xml.bind.*;

byte[] bytesOfMessage = yourString.getBytes("UTF-8");
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] bytesOfDigest = md.digest(bytesOfMessage);
String digest = DatatypeConverter.printHexBinary(bytesOfDigest).toLowerCase();

Admin · Answer

MD5 is perfectly fine if you don't need the best security, and if you're doing something like checking file integrity then security is not a consideration. In such as case you might want to consider something simpler and faster, such as Adler32, which is also supported by the Java libraries.

user_4860043 · Answer

You can generate MD5 hash for a given text by making use of the methods in the MessageDigest class in the java.security package. Below is the complete code snippet,

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.xml.bind.DatatypeConverter;

public class MD5HashGenerator 
{

   public static void main(String args[]) throws NoSuchAlgorithmException
   {
       String stringToHash = "MyJavaCode"; 
       MessageDigest messageDigest = MessageDigest.getInstance("MD5");
       messageDigest.update(stringToHash.getBytes());
       byte[] digiest = messageDigest.digest();
       String hashedOutput = DatatypeConverter.printHexBinary(digiest);
       System.out.println(hashedOutput);
   }
}

The output from the MD5 function is a 128 bit hash represented by 32 hexadecimal numbers.

In case, if you are using a database like MySQL, you can do this in a more simpler way as well. The query Select MD5(“text here”) will return the MD5 hash of the text in the bracket.

user_6367213 · Answer

You could try using Caesar.

First option:

byte[] hash =
    new Hash(
        new ImmutableMessageDigest(
            MessageDigest.getInstance("MD5")
        ),
        new PlainText("String to hash...")
    ).asArray();

Second option:

byte[] hash =
    new ImmutableMessageDigest(
        MessageDigest.getInstance("MD5")
    ).update(
        new PlainText("String to hash...")
    ).digest();

user_13849761 · Answer

Simple function using java.security.MessageDigest library

public String stringMD5Hash(String text) throws NoSuchAlgorithmException {
        MessageDigest messageDigest = MessageDigest.getInstance("MD5");
        byte[] bytes = messageDigest.digest(text.getBytes());
        StringJoiner stringJoiner = new StringJoiner("");
        for (byte b : bytes) {
            stringJoiner.add(Integer.toHexString((b & 0xFF) | 0x100).substring(1, 3));
        }
        return stringJoiner.toString();
    }

user_12331220 · Answer

I have made this using php as follows

 0 ) {
                        print "$check $try
";
                        $show = $show - 1;
                    }
                    if($goodtext == $try){
                        break;
                    }
                }
                if($goodtext == $try){
                    break;
                }
            }
            if($goodtext == $try) {
                break;  
            }
        }
        if($goodtext == $try){
            break;
        }
    }
    // Compute ellapsed time
    $time_post = microtime(true);
    print "Ellapsed time: ";
    print $time_post-$time_pre;
    print "
";
}
?>

you may refer this - source

How can I generate an MD5 hash in Java?

34 Answers