Question

develop a algorithm to implement MD5 in Java to encrypt/hash passwords with salt.

Answer 1

CODE

public class SaltedMD5Example

{

    public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchProviderException

    {

        String passwordToHash = "password";

        byte[] salt = getSalt();

         

        String securePassword = getSecurePassword(passwordToHash, salt);

        System.out.println(securePassword); //Prints 83ee5baeea20b6c21635e4ea67847f66

         

        String regeneratedPassowrdToVerify = getSecurePassword(passwordToHash, salt);

        System.out.println(regeneratedPassowrdToVerify); //Prints 83ee5baeea20b6c21635e4ea67847f66

    }

     

    private static String getSecurePassword(String passwordToHash, byte[] salt)

    {

        String generatedPassword = null;

        try {

            // Create MessageDigest instance for MD5

            MessageDigest md = MessageDigest.getInstance("MD5");

            //Add password bytes to digest

            md.update(salt);

            //Get the hash's bytes

            byte[] bytes = md.digest(passwordToHash.getBytes());

            //This bytes[] has bytes in decimal format;

            //Convert it to hexadecimal format

            StringBuilder sb = new StringBuilder();

            for(int i=0; i< bytes.length ;i++)

            {

                sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));

            }

            //Get complete hashed password in hex format

            generatedPassword = sb.toString();

        }

        catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

        }

        return generatedPassword;

    }

     

    //Add salt

    private static byte[] getSalt() throws NoSuchAlgorithmException, NoSuchProviderException

    {

        //Always use a SecureRandom generator

        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "SUN");

        //Create array for salt

        byte[] salt = new byte[16];

        //Get a random salt

        sr.nextBytes(salt);

        //return salt

        return salt;

    }

}