String secret = mConsumerSecret + "&" + mOauthToken;    SecretKey secretKey = new SecretKeySpec(secret.getBytes("US-ASCII"), "HmacSHA1");  Mac mac = Mac.getInstance("HmacSHA1");  mac.init(secretKey);    byte[] text = builder.toString().getBytes("US-ASCII");  byte[] finalText = mac.doFinal(text);  String base64Text = Base64.encodeToString(finalText, Base64.DEFAULT);  return encode(base64Text.trim());