mustafa cantürk blog

Hello! For my school project, I had been tought of crypting passwords of users. Due to the fact that, SHA1 algorithm has security problems (link) , I have decided using a SHA2. SHA2 has 3 variants: SHA256, SHA384 and SHA512. While I was searching how to implement SHA2 on Java,  I have found this link.

For SHA512 that code works:

import java.security.*;

public class cryptotest {
    public static void main(String[] args) throws NoSuchAlgorithmException {
        MessageDigest md;
        String message = "password";
        try {
            md= MessageDigest.getInstance("SHA-512");

            md.update(message.getBytes());
            byte[] mb = md.digest();
            String out = "";
            for (int i = 0; i < mb.length; i++) {
                byte temp = mb[i];
                String s = Integer.toHexString(new Byte(temp));
                while (s.length() < 2) {
                    s = "0" + s;
                }
                s = s.substring(s.length() - 2);
                out += s;
            }
            System.out.println(out.length());
            System.out.println("CRYPTO: " + out);

        } catch (NoSuchAlgorithmException e) {
            System.out.println("ERROR: " + e.getMessage());
        }
    }
}

If you want to hash password with SHA256, you can change the line:

md= MessageDigest.getInstance("SHA-512");

to

md= MessageDigest.getInstance("SHA-256");

For others:

md= MessageDigest.getInstance("MD5");
md= MessageDigest.getInstance("SHA");
md= MessageDigest.getInstance("SHA-1");
md= MessageDigest.getInstance("SHA-384");