[ziofill]

I forget who told me this story, but at some point the British tried a crazy known-plaintext attack by planting handwritten notes in dead German soldiers’ pockets that contained an “important message” to be sent, and then in the following days they would attempt to decrypt enigma communications against the known plaintext.

[a_bonobo]

Few years ago I read 'Between Silk and Cyanide': Britain's Wartime Spies and Saboteurs', the autobiography of Leo Marks who worked in the British Special Operations Executive. He designed cryptography for agents behind enemy lines (thus the title: you could print one time pads on silk, and silk was harder to discover during pat-downs than paper).

Lots of interesting stories in there, including when he suspected that Germans had captured all of their Dutch spies and were transmitting fake messages: real agents made mistakes when encoding due to stress, the Germans' fake encodings were all perfect.

[the13]

How German, LOL.

[aspenmayer]

https://en.wikipedia.org/wiki/Gardening_(cryptanalysis)

[RugnirViking]

That's not what gp was talking about.

[aspenmayer]

It was more of an allusion than a reference, but expectations in communication ought be acknowledged and accommodated, so I apologize if you misunderstood my point as it wasn’t clear from context. Please see my edit.

(My prior comment referenced Operation Mincemeat at the time of its reply, for those reading after the fact.)

[aspenmayer]

Why did you say this to me, and not also to the other person who came after me? The fact that the other person is also upvoted kind of puts your argument to rest. Being contrary isn’t a great argumentative style on HN. You have no way of knowing what GP meant.

https://news.ycombinator.com/item?id=45088082

[RugnirViking]

because the other person hadn't said their piece by the time I said this, and because I stand by the fact that it's simply wrong to conflate leaving a body from england to deceive an enemy about the indented invasion location of an operation (regular deception, no cryptographic purpose). I think it's different, cryptographically speaking, to trying to provoke the enemy to use a known plaintext to try and help breaking their code, which I find a very interesting concept. For what its worth, I also downvoted the other comment yesterday, and the third comment today. I'm frankly astonished so many people are conflating the imo clearly different ideas.

I appreciate your edit that completely replaced the topic of your post; it is now much more interesting. But unfortunately, I could not edit my comment by the time I saw you had changed it

[aspenmayer]

> For what its worth, I also downvoted the other comment yesterday

Seems like you just don’t like me. Sounds like motivated reasoning to me. But I thought you meant (my) other comment, not theirs. I think it’s possibly an issue with tone being hard to read in text. In any case, I try to add a correction instead of simply calling out mistakes, but you were right to say whatever you thought. I don’t mean to silence you, but your words had a chilling effect on my speech, so maybe give some reasoning and a correct answer next time instead of just calling someone wrong. Anyone can do that, and they too often do.

At least now I know it’s due to that argument being kind of a weak one. I thought they were concerned with the notes especially, which is why I included that reference because it specifically referred to notes. I think there may be other WW2 examples, but I couldn’t lay hand to them at the time.

> I appreciate your edit; it is now much more interesting.

I appreciate you saying that. I don’t mean to assume you don’t like me, but it seemed that way at the time you said it. Apologies for assuming, and for any offense caused.

Edit: For what it’s worth I didn’t downvote you either time, and in fact I upvoted the comment this one is in reply to.

[aspenmayer]

I can’t edit this anymore, but you are correct.

> (regular deception, no cryptographic purpose)

That is a very good distinction with a difference, and you were right to elucidate this; I only wish you had done it in your original reply to me. In any case, my stream of consciousness post above was in haste, and I think we were both editing at the time. I will try to post better. I wonder if folks are copy posting me? I honestly can’t say.

https://en.wikipedia.org/wiki/Copypasta

https://knowyourmeme.com/memes/copypasta

[W3zzy]

You can listen to the podcast, if you want.

It's called operation Mincemeat

https://pca.st/podcast/0d412ec0-af39-0139-c19f-0acc26574db2

[RugnirViking]

that's... not what gp was talking about. Why are so many people jumping in with this mistake?

Operation mincemeat wasn't a german officer, it wasn't anything about using a known plaintext to compare to coded messages, it wasn't pretending to be german documents, and it wasn't to help with cryptanalysis. About the only similarity is a dead body

[W3zzy]

You're right. The while planting messages on bodies is what put me on the wrong track.

[Angostura]

Now also a quite good West End musical

[blaesus]

Couldn't enjoy it at all. One of the first scenes shows MI6 officers, during WWII, making plans on a post-1991 world map, with reunified Germany and independent Baltic countries, etc. Kills immersion for me immediately, along with the gender politics every few minutes in a history show. Maybe I'm old fashioned.

[pimlottc]

https://en.m.wikipedia.org/wiki/Operation_Mincemeat

[jjmarr]

The story of the man[1] whose body was used to fool German intelligence during Operation Mincemeat is quite tragic:

> Michael was born in Aberbargoed in Monmouthshire in South Wales. Before leaving the town, he held part-time jobs as a gardener and labourer. His father Thomas, a coal miner, killed himself when Michael was 15, and his mother died when he was 31. Homeless, friendless, depressed, and with no money, Michael drifted to London where he lived on the streets.

> Michael was found in an abandoned warehouse close to King's Cross, seriously ill from ingesting rat poison that contained phosphorus. Two days later, he died at age 36 in St Pancras Hospital. His death may have been suicide, although he might have simply been hungry, as the poison he ingested was a paste smeared on bread crusts to attract rats.

> After being ingested, phosphide reacts with hydrochloric acid in the stomach, generating phosphine, a highly toxic gas. One of the symptoms of phosphine poisoning is pulmonary oedema, an accumulation of large amounts of liquid in the lungs, which would satisfy the need for a body that appeared to have died by drowning. Purchase explained, "This dose was not sufficient to kill him outright, and its only effect was to so impair the functioning of the liver that he died a little time afterwards". When Purchase obtained Michael's body, it was identified as being in suitable condition for a man who would appear to have floated ashore several days after having died at sea by hypothermia and drowning.

[1] https://en.wikipedia.org/wiki/William_Martin_(Royal_Marines_...

[bawolff]

> Part of the wider Operation Barclay, Mincemeat was based on the 1939 Trout memo, written by Rear Admiral John Godfrey, the director of the Naval Intelligence Division, and his personal assistant, Lieutenant Commander Ian Fleming

Wonder if we'll ever see it on a bond movie.

[mikk14]

Not a Bond one, but there's already a movie about it: https://www.imdb.com/title/tt1879016/

[henrik_w]

The book by Ben Macintyre, "Operation Mincemeat: How a Dead Man and a Bizarre Plan Fooled the Nazis and Assured an Allied Victory", is very good.

https://www.goodreads.com/book/show/7632329-operation-mincem...

[Cthulhu_]

That's cool, I hadn't heard of that. I did hear that they made the mistake of repeating certain phrases, including signing everything with a "heil hitler", but also something about the weather forecast starting the same way every time.