Java – Create file checksum with SHA and MD5

In this article, we will show you how to use a SHA-256 and MD5 algorithm to generate a checksum for a file.

1. MessageDigest.getInstance(“algorithm”)
2. Apache Commons Codec

1. MessageDigest

d:\server.log

hello world

1.1 Generate a file checksum with a SHA256 algorithm.

FileCheckSumSHA.java

package com.favtuts.crypto.hash;

import java.io.FileInputStream;
import java.io.IOException;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class FileChecksum {

    public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
        
        MessageDigest md = MessageDigest.getInstance("SHA-256"); // SHA, MD2, MD5, SHA-256, SHA-384...
        String hex = checksum("/home/tvt/workspace/favtuts/server.log", md);
        System.out.println(hex);
    }
    
    private static String checksum(String filepath, MessageDigest md) throws IOException {

        // file hashing with DigestInputStream
        try (DigestInputStream dis = new DigestInputStream(new FileInputStream(filepath), md)) {
            while(dis.read() != -1) ; // empty loop to clear the data
            md = dis.getMessageDigest();
        }

        // bytes to hex
        StringBuilder result  = new StringBuilder();
        for (byte b : md.digest()) {
            result.append(String.format("%02x", b));
        }
        return result.toString();
    }
}

Output

db42dbb4d57ff715c32d5b85fa8c340930590360f2db86280af75496c30b18a9

1.2 Generate a file checksum with a MD5 algorithm.

FileCheckSumMD5.java

package com.favtuts.crypto.hash;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class FileChecksum {

    public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
         
        MessageDigest md = MessageDigest.getInstance("MD5"); 
        String hex = checksum("/home/tvt/workspace/favtuts/server.log", md);
        System.out.println(hex);
    }
    
    private static String checksum(String filepath, MessageDigest md) throws IOException {

        // DigestInputStream is better, but you also can hash file like this.
        try (InputStream fis = new FileInputStream(filepath)) {
            byte[] buffer = new byte[1024];
            int nread;
            while ((nread = fis.read(buffer)) != -1) {
                md.update(buffer, 0, nread);
            }
        }

        // bytes to hex
        StringBuilder result  = new StringBuilder();
        for (byte b : md.digest()) {
            result.append(String.format("%02x", b));
        }
        return result.toString();
    }

}

Output

911e319109c6ff83cea342494e6599d4

2. Apache Commons Codec

pom.xml

	<dependency>
		<groupId>commons-codec</groupId>
		<artifactId>commons-codec</artifactId>
		<version>1.11</version>
        </dependency>

2.1 File checksum.

FileCheckSum.java

package com.favtuts.crypto.hash;

import java.io.FileInputStream;
import java.io.IOException;

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

public class FileChecksum {

    public static void main(String[] args) throws IOException {
        
        String filePath = "/home/tvt/workspace/favtuts/server.log";
  
        String checksumSHA256 = DigestUtils.sha256Hex(new FileInputStream(filePath));
        System.out.println("checksumSHA256 : " + checksumSHA256);

        String checksumMD5 = DigestUtils.md5Hex(new FileInputStream(filePath));
        System.out.println("checksumMD5 : " + checksumMD5);
    }

}

Output

checksumSHA256 : db42dbb4d57ff715c32d5b85fa8c340930590360f2db86280af75496c30b18a9
checksumMD5 : 911e319109c6ff83cea342494e6599d4

Download Source Code

$ git clone https://github.com/favtuts/java-core-tutorials-examples

$ cd java-crypto/hash

References

1. Java – List of available MessageDigest Algorithms
2. Apache Commons Codec
3. Java – How to convert Bytes to Hex
4. Wikipedia – MD5
5. MessageDigest JavaDoc
6. Java SHA Hashing Example
7. Java MD5 Hashing Example