code: public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
  		
  		HttpServletResponse res = (HttpServletResponse)response;
  		HttpServletRequest req = (HttpServletRequest)request;
  		
  		String et = req.getParameter("e");
  		String h = req.getParameter("h");
  		
  		if(null == et || null == h) {
  			badRequest(res);
  			LOG.warn("et & h attributes are null; Bad request from IP: " + req.getRemoteAddr());
  			return;
  		}
  			
  		String baseUrl = req.getRequestURI();
  		String passKey = secureUriMapper.getPassKey(baseUrl);		
  		
  		String salt = passKey + baseUrl + "?e=" + et;
  		String hash = SpringExtensionsUtil.getMD5(salt);		
  		if(!hash.trim().equals(h)) {
  			badRequest(res);
  			LOG.warn("Hash Value doesn't match; Bad request from IP: " + req.getRemoteAddr());
  			return;
  		}
  		
  		long expiryTime = Long.parseLong(et);		
  		if(expiryTime > 0 && !(new Date().getTime() <= expiryTime)) {
  			badRequest(res);
  			LOG.warn("Secure Link expried, link accessed from IP: " + req.getRemoteAddr());
  			return;
  		}		
  		
  		/** making chain call for following filters*/
  		chain.doFilter(request, response);
  	}
docs: {@inheritDoc}
  
  @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)