Java MD5 Hashing Example

The MD5, defined in RFC 1321, is a hash algorithm to turn inputs into a fixed 128-bit (16 bytes) length of the hash value.

Note
MD5 is not collision-resistant – Two different inputs may producing the same hash value. Read this MD5 vulnerabilities. There are many fast and secure hashing algorithms like SHA3-256 or BLAKE2; For password hashing, we can use Bcrypt or Argon2. If possible, do not use MD5 in any security-related cryptography tasks.

In Java, we can use MessageDigest to generate the MD5 algorithm.


  MessageDigest md = MessageDigest.getInstance("MD5");
  byte[] result = md.digest(input);

1. Java MD5 Hashing

This Java example uses MD5 to produce a hash value from a String.

MD5Utils.java

package com.mkyong.crypto.hash;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Utils {

    private static final Charset UTF_8 = StandardCharsets.UTF_8;
    private static final String OUTPUT_FORMAT = "%-20s:%s";

    private static byte[] digest(byte[] input) {
        MessageDigest md;
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalArgumentException(e);
        }
        byte[] result = md.digest(input);
        return result;
    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            sb.append(String.format("%02x", b));
        }
        return sb.toString();
    }

    public static void main(String[] args) {

        String pText = "Hello MD5";
        System.out.println(String.format(OUTPUT_FORMAT, "Input (string)", pText));
        System.out.println(String.format(OUTPUT_FORMAT, "Input (length)", pText.length()));

        byte[] md5InBytes = MD5Utils.digest(pText.getBytes(UTF_8));
        System.out.println(String.format(OUTPUT_FORMAT, "MD5 (hex) ", bytesToHex(md5InBytes)));
        // fixed length, 16 bytes, 128 bits.
        System.out.println(String.format(OUTPUT_FORMAT, "MD5 (length)", md5InBytes.length));

    }

}

Output

Terminal

Input (string)      :Hello MD5
Input (length)      :9
MD5 (hex)           :e5dadf6524624f79c3127e247f04b548
MD5 (length)        :16

Try another String, for example, Hello MD5 Hello MD5. The input length varies, but the output of the MD5 hash value is still 128 bits, 16 bytes.

Output

Terminal

Input (string)      :Hello MD5 Hello MD5
Input (length)      :19
MD5 (hex)           :6219b1bc3542949e012616059409f1cc
MD5 (length)        :16

2. Java MD5 File Checksum.

For the file checksum, the ideas are the same, but we need some extra IO classes to handle the input stream.

Here is a text file.

c:\\test\\readme.txt

Hello MD5

This Java program will generate an MD5 file checksum from a file.

MD5Utils.java

package com.mkyong.crypto.hash;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Utils {

    private static final Charset UTF_8 = StandardCharsets.UTF_8;
    private static final String OUTPUT_FORMAT = "%-20s:%s";

    private static byte[] checksum(String filePath) {

        MessageDigest md;
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalArgumentException(e);
        }

        try (InputStream is = new FileInputStream(filePath);
             DigestInputStream dis = new DigestInputStream(is, md)) {
            while (dis.read() != -1) ; //empty loop to clear the data
            md = dis.getMessageDigest();
        } catch (IOException e) {
            throw new IllegalArgumentException(e);
        }
        return md.digest();

    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            sb.append(String.format("%02x", b));
        }
        return sb.toString();
    }

    public static void main(String[] args) {

        String file = "c:\\test\\readme.txt";
        System.out.println(String.format(OUTPUT_FORMAT, "Input (file) ", file));
        System.out.println(String.format(OUTPUT_FORMAT, "MD5 (checksum hex) ", bytesToHex(checksum(file))));

    }

}

Output

Terminal

Input (file)        :c:\test\readme.txt
MD5 (checksum hex)  :e5dadf6524624f79c3127e247f04b548

3. Apache Commons Codec

This example uses the commons-codec library to generate the MD5 hash value.

pom.xml

  <dependency>
      <groupId>commons-codec</groupId>
      <artifactId>commons-codec</artifactId>
      <version>1.14</version>
  </dependency>

3.1 MD5 hash value from a String.


import org.apache.commons.codec.digest.DigestUtils;

    String pText = "Hello MD5";
    System.out.println(DigestUtils.md5Hex(password));

Output

Terminal

e5dadf6524624f79c3127e247f04b548

3.2 MD5 hash value from a File.


  try (InputStream is = new FileInputStream("c:\\test\\readme.txt")) {
      String checksum = DigestUtils.md5Hex(is);
      System.out.println(checksum);
  } catch (IOException e) {
      e.printStackTrace();
  }

Output

Terminal

e5dadf6524624f79c3127e247f04b548

Download Source Code

$ git clone https://github.com/mkyong/core-java

$ cd java-crypto

References

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mkyong

Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter. If you like my tutorials, consider make a donation to these charities. Read all published posts by

Comments

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Vladimir
Guest
Vladimir

My friend, thank you very much from Russia !!!!

Cafebabe2018
Guest
Cafebabe2018

for (int i = 0; i < byteData.length; i++) {
sb.append(String.format("%02x", byteData[i]));
}

Qazi Jalil
Guest
Qazi Jalil

but if i do it over some file it works correctly but if i change its path or location of file its hash changes why me not able to fix this error

Eugen Maysyuk
Guest
Eugen Maysyuk

You forgot to close FileInputStream.

Nishu
Guest
Nishu

Its giving a different hash every time with the same input file which should not be the case with MD5 algorithm. I think there is some problem in this code

Napster85
Guest
Napster85

What about if you use this:

sb.append(String.format(“%02X”, buffer[i]));

😉

dinesh riyadh
Guest
dinesh riyadh

thank you soo much brother. you are the best.

julio
Guest
julio

alguien me dice como desencriptar esta clave E67480325049070253

Prashant
Guest
Prashant

What is the point to generate md5 hash of a password if that cant be reversed?

guest
Guest
guest

You save the generated md5 hash in a file or any other method, If someone fojnd it, s/he wont be able to get the original password (except by brute force) … anyway, when you or anyone else enter the password, you hash the entered password and compare it to the md5 you generated previously.

so in breif, instead of comparing the explict passwords to check if they match, you check theirs hashs.

Ahmed ElZayady
Guest
Ahmed ElZayady

Hi .. The string method above isn’t working fine if the string contains a £ sign, don’t know why. On other hand, the function provided in this link http://www.asjava.com/core-java/java-md5-example/ did work fine with £. May be it is something you might be interested to look into.

Murali Mohan
Guest
Murali Mohan

The world is a fast-changing place. Check out Apache Shiro’s cryptography capabilities.

https://www.youtube.com/watch?v=5ZepGFzYHpE

itsvenkis
Guest
itsvenkis

Hi!!! I really unable to understand why you had

Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1)

instead of

Integer.toString((byteData[i] & 0xff), 16)

If it is just for padding zeros you could have checked the length and added a zero. May be I am missing the whole point. Can you pelase help me understand?

none
Guest
none

Yes, it’s for padding, and It’s just easier syntax than introducing conditional branching.

elton
Guest
elton

hello sir,
i want a simple java code to calculate md5 of any input i give from a keyboard

trackback
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siri
Guest
siri

I have 100 file (which are not stored on my computer)that are located on a server and I have path to each one of them, I need a code to calculate the MD5 of each one of the and store it in an excel sheet individually.

Wilson
Guest
Wilson

Is there any way convert the digested “e10adc3949ba59abbe56e057f20f883e” key to original password “123456”. If you know please let us know.

Thanks
Wilson.

Tewari
Guest
Tewari

MD5 is one way digest algorithm, this means that you are not supposed/allowed to convert the hash back to text. I would not suggest you to go with Rainbow tables since you would then have to secure and manage the rainbow table itself, besides the bigger the table gets the higher the seek time gets and is therefore not effective. If you want to encrypt text so that it can be converted back to original text you can try base64encoding with secret key.

Saifur Rahman Mohsin
Guest
Saifur Rahman Mohsin

You can do this by generating a rainbow table and then comparing the hash with original text. However longer texts will not give the correct output for obvious reasons..!

Facepalm
Guest
Facepalm

Idiot.

natesan
Guest
natesan

Dear Sir,
in this example (ff) variable showing some errors.how to rectify the error. thank you sir.the error was ff cannot be resolved to a variable.

nordin
Guest
nordin

md5 is useful when hashing filenames for some reason. I’ll use this snippet of code to hash imagefile names, it’s temporary for a few weeks and than I’ll remove them. The advantage is that this hash method is less cpu intensive and the chances to have the same hash values are very very small. Furthermore, this is a nice simple example, so using a sha-1 instead of md5 is almost the same. Thank you for your snippet 🙂

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[…] Java MD5 Hashing Example. […]

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Cristian
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Cristian

Hello, I am wondering why you would use MD5, an algorithm thats has already been broken instead of something like GrandCentral which creates a password digest based on the time of day using SHA-512. GrandCentral also includes the SimpleCrypto class which can generate hashes and checksums using MD5, SHA1, SHA-256, SHA-384 and SHA-512. Just a suggestion. http://code.google.com/p/grandcentral/

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santosh
Guest
santosh

sir,
give me suggestion for password hashing using md 5 algorithm in java.

Rocky Madden
Guest
Rocky Madden

Been moving towards always using SHA hashing myself, especially with recent CPU processor support/improvements being added each generation. Trusty old MD5 doesn’t let down most of the time though.

gli00001
Guest
gli00001

new BigInteger(1, md.digest()).toString(16) should save the loop using stringBuffer