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Famous cryptographers’ tombstone cryptogram decrypted (nakedsecurity.sophos.com)
409 points by wglb 8 days ago | hide | past | web | 35 comments | favorite

At first glance, having no information on this other than a title and an image, I assumed there was some data encoded in the odd pattern on the flags at the top of the tombstone. I then read through the article waiting to learn what was there, and of course it was never mentioned.

A google search turned up a higher-resolution photo of the tombstone: http://elonka.com/friedman/Tombstone.JPG

The lines on the flags appear to be ordinary stripes, with nothing encoded in them. So I guess I can thank my own imagination for turning an otherwise fascinating story into a bit of a disappointment.

Two flags crossing a torch is the insignia of the U.S. Army Signal Corps. The stripes here stand in for the areas of the flags that are red in the insignia.

I'm confused, they definitely mentioned the what was decrypted. It was the "Knowledge is Power" using different types of fonts decode his initials.

Thank you for the high res photo, it was cool to actually be able to see the close up lettering.

You don’t have a lot of artistic license for headstones in Arlington National Cemetery.

also, a book just came out about Elizebeth Friedman and how a lot of her contributions to cryptology and the birth of sigint in general have been erased from histroy: https://www.amazon.com/Woman-Who-Smashed-Codes-Outwitted-ebo...

it's supposed to be very good, but I just started it last night so don't have much of an opinion yet.

It is utterly fantastic, a gripping, fascinating, heart-breaking love story.

According to the author, it's in plans to become a mini-series.

Excellent book; I highly recommend it.

Confirmed, it’s great

Link to the original source is buried within - http://elonka.com/friedman/FriedmanTombstone.pdf

Awww, that's lovely.

Geocaching tends to use bacon cyphers extensively, as they are very useful for hiding messages in plain sight.

This discussion of ciphers vs puzzles has reminded me of one of my favorite books growing up. It was Helen Fouché Gaines Elementary Cryptanalysis. I found it in the library in 1962 and treasured the copy my Aunt purchased for me.

This book predates the age of computers so every chapter introduces the common ciphers, including, military and diplomatic ones, in use at the time (I believe the first edition was written in 1943) along with the methods used to attack them.

Over time I worked my way through the exercises that appear at the end of each chapter. Computers make light work of these challenging puzzles now, but it’s still fun to write programs to break these old cipher systems.

Around 1987, I approached a very prominent professor in my CS program about being my Ph.D. dissertation advisor for a research project on Cryptography. He said that I should work in another area because cryptography had all been figured out and it didn’t look like there was anything interesting left in that field!

Nice little cryptogram, but they didn't secure the side-channel papers.

My nit here would be that these things aren't "ciphers" so much as they are "puzzles".

'Baconian cipher' is a particular kind of steganography, invented by Francis Bacon - he wrote about it and called it a 'cipher' in 1605. This is really more of an SNL Coffee Talk topic than a nit - 'Bacon ciphers are neither ciphers nor made of bacon, talk amongst yourselves'.

You're the worst.

There is an old Wikipedia grudge behind my nit, unfortunately.

How do you get there? You have a message text and you have a cipher text and you have an algorithm to go from one to the other. Seems like a cipher to me.

It's splitting hairs to make a distinction, but a cipher has an intended recipient and potential eavesdroppers, whereas a puzzle has no known recipient other than the potential eavesdroppers.

A good cipher has to be readable by the intended recipient, and not by eavesdroppers, whereas a good puzzle cannot be impossible to crack.

In that sense, DRM is a sort of anti-puzzle, as the intended recipients are treated as the eavesdroppers, instead of the other way around.

> whereas a good puzzle cannot be impossible to crack.

This is a very important distinction. It would be no fun if the cipher on a given cryptographer's tombstone were created with a one-time pad.

Well, a certain type of person would find it fun to put an unsolvable puzzle on their own tombstone.

Interestingly a one time pad may be crackable. Its theoretical uncrackability is only true if a truly random number generator is used. Most cryptography is fine with urandom but a one time pad requires using something like radioactive decay to generate your pad.

This is one reason (among many) why it's impractical for most crypto purposes.

Assuming a flawless CSRNG, 128 bits of entropy is more than enough to withstand current attack power. It's hard to predict the future -- quantum computers employing Grover's algorithm could conceivably have 2x or more attack power per unit energy -- but 256 bits should be adequate for a long time.

It's fine to use low-grade sources of entropy like timestamps as long as we have enough of it. I might only generate a few bits of actual entropy per second when I move my mouse in somewhat predictable arcs, but if I keep at it for a while, I'll generate 256 bits of entropy eventually.

If the one-time pad were public somewhere, how hard would it be to find it? Say, if it were indexed by Google?


I would expect that the message was sent by Willaim after he died to people who knew him. A sort of inside joke, that people like me, seeing his tombstone would completely miss.

That said, I could see one making the case that it is steganography.

I don't think 'good' and 'bad' really come into play, a caesar cipher is still a caesar cipher even if it is pretty easy to crack. But when you see it, it doesn't look like something else.

Ideally, it should be "cryptographically" difficult to distinguish a steganographically-encoded message from an ordinary (noisy) encoding. The comparison between these kinds of cryptograms and steganography does about as much violence to the concept of steganography as it does to the concept of cryptography.

A decent threshold test is Kerckhoffs's principle.

Okay, read up on Kerckhoff.

I realize that when I talk about ciphers I don't distinguish between those which are easily reversed and those which are difficult to reverse. Kerckhoff was really concerned with cryptographic systems as a whole but his first principle that "The system must be practically, if not mathematically, indecipherable." would seem to be a function of the environment and the adversary.

To illustrate my thinking, I consider the mechanism on a Hallmark Diary cover that prevents you from opening it without the 'key' just as much a "lock" as the mechanism on the file cabinet that keeps secret material secret.

Given that, would my understanding be correct that any information obscuring or access preventing device which is susceptible to a 'lay person' inverting it, is, in your definition of things, a puzzle?

If that is correct, is the caesar cipher also a puzzle?

The conventional way to look at it would be to call rotation ciphers toy ciphers. They ostensibly depend on a key (the rotation) but fall apart trivially even without them.

I think the point downthread, about cryptograms being designed deliberately so that unrelated readers might eventually have some hope of figuring them out, adds nicely to the definition.

On the other hand, the Caesar cipher was supposedly really used by Caesar, and not with the intention of unrelated readers figuring it out. According to Wikipedia:

> It is unknown how effective the Caesar cipher was at the time, but it is likely to have been reasonably secure, not least because most of Caesar's enemies would have been illiterate and others would have assumed that the messages were written in an unknown foreign language.

So perhaps it’s best to think of it as a real cipher that was obsoleted by technological advances... much as modern ciphers can be obsoleted by advances in cryptanalytic techniques or computer hardware.

For a more modern example you could consider Navajo code talkers in WWII. As I just learned (you might know way more about this than me :), the code talkers weren’t just translating their messages into the Navajo language; rather, they typically spelled out English text using one code word per letter. Thus, what they did can definitely be seen as a cipher, in more than just the vague sense of a way to keep a message secret. And the list of code words could be seen as a key... but only to some extent. If they had just invented a word-per-letter code in English, the enemy would have been able to write down the words, and perhaps ultimately decipher the code using frequency analysis, which was a well-known technique at that point. Much of the code’s security rather depended on the use of the Navajo language, which was tonally complex, had few speakers, and had no published dictionaries at the time. These are all factors that don’t follow Kerckhoff’s principle: if the enemy had obtained Navajo speakers and proceeded to decipher the code, rekeying with a new word list wouldn’t have brought back the original level of security.

Of course, the scheme would not stand up well to modern computer-based techniques, and if used today would have to mostly be considered a toy cipher. But in its original historical context it was not a toy.

(And on the flipside, there are other historical ciphers that are just as obsolete thanks to computers, but did follow Kerckhoff’s principle with respect to attacks available at the time - such as the Enigma machine.)

Anyone know why Twitter blocks any attempt to tweet this URL?

Works for me, wait... are you from sophos?

It worked when I tweeted the google amp URL, oddly.

And LOL, not from Sophos. I assumed it was because it had the word "naked" in the URL, but it was odd because I attempted to tweet it many times and it failed UNTIL I used the google amp version of the URL.

not loading for me, but interested in reading!

I was able to get to it just now.

Interesting and good read. Thank you.

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