"An example of ... function secrecy, was the British utilization of the intelligence gathered by cryptanalysts during World War II (Project Ultra). Since one of the most valuable assets in the war was the access to German communications made possible by cracking their ciphers, it was of extreme importance that the Nazis not know their code had been penetrated. To insure this, all information derived from Ultra intercepts was "discovered" - that is, overtly confirmed - by other means. If Ultra had located an important target for a bombing raid, for instance, the military made sure some reconnaissance planes would be sent there first to hide from the Germans the true source of the information.
"An instance of ... parasitic secrecy, may be found in the same war. The British espionage agency SIS, was, despite its legendary status, a largely inefficient organization mistrusted by the military. In order to guarantee their own survival, they monopolized access to the Ultra operation (conducted by GCCS, the Government Code and Cipher School) and presented the Ultra triumphs as their own successes. In the process of concealing this parasitism they squandered some of the Ultra material, created suspicions at GCCS against politicians and in general decreased the functionality of communications-interception and code-breaking as a whole."
(Manuel De Landa, War in the Age of Intelligent Machines, pp. 186-187)