That reminds me of G. H. Estabrooks
"This psychologist reminisces about his long career as a hypnotist: how he "programmed" American spies with hypnosis:"
"One of the most fascinating but dangerous applications of hypnosis is its use in military intelligence. This is a field with which I am familiar though formulating guide lines for the techniques used by the United States in two world wars.
Communication in war is always a headache. Codes can be broken. A professional spy may or may not stay bought. Your own man may have unquestionable loyalty, but his judgment is always open to question.
The "hypnotic courier," on the other hand, provides a unique solution. I was involved in preparing many subjects for this work during World War II. One successful case involved an Army Service Corps Captain whom we''l call George Smith.
Captain Smith had undergone months of training. He was an excellent subject but did not realize it. I had removed from him, by post-hypnotic suggestion, all recollection of ever having been hypnotized.
First I had the Service Corps call the captain to Washington and tell him they needed a report of the mechanical equipment of Division X headquartered in Tokyo. Smith was ordered to leave by jet next morning, pick up the report and return at once. Consciously, that was all he knew, and it was the story he gave to his wife and friends.
Then I put him under deep hypnosis, and gave him -- orally -- a vital message to be delivered directly on his arrival in Japan to a certain colonel -- let's say his name was Brown -- of military intelligence. Outside of myself, Colonel Brown was the only person who could hypnotize Captain Smith. This is "locking." I performed it by saying to the hypnotized Captain: "Until further orders from me, only Colonel Brown and I can hypnotize you. We will use a signal phrase 'the moon is clear.' Whenever you hear this phrase from Brown or myself you will pass instantly into deep hypnosis." When Captain Smith re-awakened, he had no conscious memory or what happened in trance. All that he was aware of was that he must head for Tokyo to pick up a division report.
On arrival there, Smith reported to Brown, who hypnotized him with the signal phrase. Under hypnosis, Smith delivered my message and received one to bring back. Awakened, he was given the division report and returned home by jet. There I hypnotized him once more with the signal phrase, and he spieled off Brown's answer that had been dutifully tucked away in his unconscious mind.
The system is virtually foolproof. As exemplified by this case, the information was "locked" in Smith's unconscious for retrieval by the only two people who knew the combination. The subject had no conscious memory of what happened, so could not spill the beans. No one else could hypnotize him even iv they might know the signal phrase."
https://www.whale.to/b/estabrooks.html
I have both books, it's hard to watch more clearly the different layers of truth, one for the public (only an expert on public opinion...) and the more classified one (real mind hacking)