Java MD5 Hashing Example

MD5 is a widely used hashing algorithm in many companies and industries, here are two examples for the MD5 implementation.

1. File checksum with MD5

It will use MD5 hashing algorithm to generate a checksum for file “c:\\loging.log”.

package com.mkyong.test;
 
import java.io.FileInputStream;
import java.security.MessageDigest;
 
public class MD5CheckSumExample 
{
    public static void main(String[] args)throws Exception
    {
        MessageDigest md = MessageDigest.getInstance("MD5");
        FileInputStream fis = new FileInputStream("c:\\loging.log");
 
        byte[] dataBytes = new byte[1024];
 
        int nread = 0; 
        while ((nread = fis.read(dataBytes)) != -1) {
          md.update(dataBytes, 0, nread);
        };
        byte[] mdbytes = md.digest();
 
        //convert the byte to hex format method 1
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < mdbytes.length; i++) {
          sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
        }
 
        System.out.println("Digest(in hex format):: " + sb.toString());
 
        //convert the byte to hex format method 2
        StringBuffer hexString = new StringBuffer();
    	for (int i=0;i<mdbytes.length;i++) {
    		String hex=Integer.toHexString(0xff & mdbytes[i]);
   	     	if(hex.length()==1) hexString.append('0');
   	     	hexString.append(hex);
    	}
    	System.out.println("Digest(in hex format):: " + hexString.toString());
    }
}

Output

Digest(in hex format):: e72c504dc16c8fcd2fe8c74bb492affa
Digest(in hex format):: e72c504dc16c8fcd2fe8c74bb492affa

2. Hashing String with MD5

It will use MD5 hashing algorithm to generate a hash value for a password “123456″.

package com.mkyong.test;
 
import java.security.MessageDigest;
 
public class MD5HashingExample 
{
    public static void main(String[] args)throws Exception
    {
    	String password = "123456";
 
        MessageDigest md = MessageDigest.getInstance("MD5");
        md.update(password.getBytes());
 
        byte byteData[] = md.digest();
 
        //convert the byte to hex format method 1
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < byteData.length; i++) {
         sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
        }
 
        System.out.println("Digest(in hex format):: " + sb.toString());
 
        //convert the byte to hex format method 2
        StringBuffer hexString = new StringBuffer();
    	for (int i=0;i<byteData.length;i++) {
    		String hex=Integer.toHexString(0xff & byteData[i]);
   	     	if(hex.length()==1) hexString.append('0');
   	     	hexString.append(hex);
    	}
    	System.out.println("Digest(in hex format):: " + hexString.toString());
    }
}

Output

Digest(in hex format):: e10adc3949ba59abbe56e057f20f883e
Digest(in hex format):: e10adc3949ba59abbe56e057f20f883e