code: public void close() 
      {
          forwardEngine.close();
          if (forwardEngine != reverseEngine)
              reverseEngine.close();
  
          Iterator<Map.Entry<Long, SRTCPCryptoContext>> iter
              = contexts.entrySet().iterator();
  
          while (iter.hasNext()) 
          {
              Map.Entry<Long, SRTCPCryptoContext> entry = iter.next();
              SRTCPCryptoContext context = entry.getValue();
  
              iter.remove();
              if (context != null)
                  context.close();
          }
      }
docs: Close the transformer and underlying transform engine.
  
  The close functions closes all stored crypto contexts. This deletes key data
  and forces a cleanup of the crypto contexts.