code: public void close() {
  		forwardEngine.close();
  		if (forwardEngine != reverseEngine) {
  			reverseEngine.close();
  		}
  		for (Long ssrc : contexts.keySet()) {
  			SRTPCryptoContext context = contexts.get(ssrc);
  			if (context != null) {
  				context.close();
  				contexts.remove(ssrc);
  			}
  		}
  	}
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.