import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Hash {
    private static MessageDigest md;

    static {
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            // do nothing
        }
    }

    public static byte[] encode(String str) {
        if (str == null) {
            return null;
        }

        return digest(str.getBytes());
    }

    public static byte[] encode(byte[] bytes) {
        if (bytes == null) {
            return null;
        }

        return digest(bytes);
    }

    private static byte[] digest(byte[] msg) {
        md.reset();
        return md.digest(msg);
    }
}