How to Do Java SHA Hashing

SHA-2 is believe the most secure hashing algorithm as this article is written, here are few examples for the SHA implementation. The possible MessageDigest algorithm are SHA-1, SHA-256, SHA-384, and SHA-512, you can check the reference for the detail.It will use SHA-256 hashing algorithm to generate a checksum for file “c:\\loging.log”.

package org.best.example;
 
import java.io.FileInputStream;
import java.security.MessageDigest;
 
public class SHACheckSumExample 
{
    public static void main(String[] args)throws Exception
    {
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        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("Hex format : " + sb.toString());
 
       //convert the byte to hex format method 2
        StringBuffer hexString = new StringBuffer();
     for (int i=0;i<mdbytes.length;i++) {
       hexString.append(Integer.toHexString(0xFF & mdbytes[i]));
     }
 
     System.out.println("Hex format : " + hexString.toString());
    }
}

Output

Hex format : 21a57f2fe765e1ae4a8bf15d73fc1bf2a533f547f2343d12a499d9c0592044d4
Hex format : 21a57f2fe765e1ae4a8bf15d73fc1bf2a533f547f2343d12a499d9c0592044d4