bitmex Signature java

import java.io.UnsupportedEncodingException;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import org.knowm.xchange.bitmex.service.BitmexDigest;
import org.knowm.xchange.utils.nonce.ExpirationTimeFactory;
import si.mazi.rescu.SynchronizedValueFactory;
public class SignatureUtil {
 private SynchronizedValueFactory<Long> nonceFactory = new ExpirationTimeFactory(30);
 
 private Long EXPIRES = (long)0;
 private String API_SECRET;
 private String API_KEY;
 public SignatureUtil(String API_KEY,String API_SECRET){
  this.API_SECRET = API_SECRET;
  this.API_KEY = API_KEY;
 }
 
 public String bitmex_signature() throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
  BitmexDigest BD = BitmexDigest.createInstance(API_SECRET);
  String API_SIGNATURE = "";
  String ENDPOINT = "/realtime";
  String VERB = "GET";
  String BITMEX_URL ="wss://www.bitmex.com";
  EXPIRES = nonceFactory.createValue();
  String data = VERB+ENDPOINT+String.valueOf(EXPIRES);
  return BD.digestString(data);
 }
 public String getAPI_SECRET() {
  return API_SECRET;
 }
 public void setAPI_SECRET(String aPI_SECRET) {
  API_SECRET = aPI_SECRET;
 }
 public String getAPI_KEY() {
  return API_KEY;
 }
 public void setAPI_KEY(String aPI_KEY) {
  API_KEY = aPI_KEY;
 }
 public Long getEXPIRES() {
  return EXPIRES;
 }
 public void setEXPIRES(Long eXPIRES) {
  EXPIRES = eXPIRES;
 }
}
xchange 활용한 wss 적용 
String bitmex_signature = signatureUtil.bitmex_signature();
ws.sendText("{\"op\" : \"authKeyExpires\", \"args\" : [\""+signatureUtil.getAPI_KEY()+"\","+signatureUtil.getEXPIRES()+",\""+bitmex_signature+"\"]}");