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GCHQ Cracks Frank Sidebottom's Codes

bbc.co.uk

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Re: GCHQ Cracks Frank Sidebottom's Codes

#31

Post by rocqua »

LeoPanthera wrote: post #3
bcherny wrote: post #2

Any more details on how the encoding worked? Was this just a substitution cypher with some gibberish sprinkled in?

Since the article mentions finding duplicate symbols which corresponded to duplicate letters in words, it's probably a simple substitution cipher. Such codes can usually be broken with a combination of frequency analysis, and guesswork. This one was apparently made more difficult by the fact that every other symbol was random. (And apparently using some symbols that did not otherwise appear in the code.)

It feels like they could've figured that out by simply looking at the distribution of triangles on the inside as compared to the outside.

Re: GCHQ Cracks Frank Sidebottom's Codes

#32

Post by rocqua »

dtf wrote: post #28
cortesoft wrote: post #8

Earlier quoted context omitted.

Nonce is short for "number used only once"

Once is from the Middle English "anes", meaning "one". Nonce is from "then anes", meaning "the one". The "-n" got smooshed into the latter word, to become "nonce", rather like "an ewt" became "newt".

Is the term that old? I was told it literally meant N(umber)once.

Re: GCHQ Cracks Frank Sidebottom's Codes

#33

Post by rocqua »

manquer wrote: post #27
jdietrich wrote: post #24

Earlier quoted context omitted.

The very complex modern approaches to cryptanalysis still borrow from the oldest attacks. A simple substitution cipher is easily broken by frequency analysis - find the most common letter in the ciphertext and it'll probably be E in the plaintext. Nothing so simple would work today, but we often see vulnerabilities in cryptosystems due to pseudorandom number generators with inadequate entropy. It's the same basic pri…

frequency analysis works easily if you know the source language, i.e. English in this case, while entropy of the message is critical to cracking, complex approaches are not the only ones which are immune to attacks, for example simple ciphers like using a one time pad is mathematically impossible to crack.

The power of a one time pad relies on the inherent entropy of the pad though. So attacks against a real one time pad still need to deal with entropy.

Re: GCHQ Cracks Frank Sidebottom's Codes

#34

Post by [deleted] »

ozzmotik wrote: post #10
paulgb wrote: post #7

If Frank Sidebottom is an unfamiliar name, I recommend the short audiobook Frank by Jon Ronson as an entertaining story. Jon played keyboards in his band and is an entertaining writer.

oh wow thanks for sharing that! I had never heard of frank but i definitely have heard of jon ronson from his research and look into psychopathy. oh and the men who stare at goats, of course. anyway i must now add yet another line to my ledger of things i really should be looking into

[deleted]

Re: GCHQ Cracks Frank Sidebottom's Codes

#35

Post by TeMPOraL »

lisper wrote: post #21
herodotus wrote: post #13

Earlier quoted context omitted.

A "nonce word" is a word that is created to be used once. For example, if we were surfing off the coast near the Kruger National Park, we might send this tweet: "We are on Surfari!" The wikipedia entry for Cryptographic nonce says: "It is similar in spirit to a nonce word, hence the name."

Also known as a hapax legomenon.

I... don't understand how it works. Isn't the Wikipedia page listing these words essentially invalidate their "hapax legomenon" status?

Also, GP's "Surfari" doesn't sound like a word meant to be used once, but as a word meant to be funny and with high probability of becoming a piece of jargon between a band of friends. My wife & I invent words like these all the time (half of them being born from misspelling or moments of confusions). Are they "nonces" too, even though we keep using them?

Re: GCHQ Cracks Frank Sidebottom's Codes

#36

Post by dtf »

rocqua wrote: post #32
dtf wrote: post #28

Earlier quoted context omitted.

Once is from the Middle English "anes", meaning "one". Nonce is from "then anes", meaning "the one". The "-n" got smooshed into the latter word, to become "nonce", rather like "an ewt" became "newt".

Is the term that old? I was told it literally meant N(umber)once.

Yes, the construction "for the nonce" goes back to the Middle Ages. The concept of a "nonce word" goes back to 1884, according to this article.

https://www.dailywritingtips.com/nonce-words-for-the-nonce-a...

Re: GCHQ Cracks Frank Sidebottom's Codes

#37

Post by OJFord »

rocqua wrote: post #32
dtf wrote: post #28

Earlier quoted context omitted.

Once is from the Middle English "anes", meaning "one". Nonce is from "then anes", meaning "the one". The "-n" got smooshed into the latter word, to become "nonce", rather like "an ewt" became "newt".

Is the term that old? I was told it literally meant N(umber)once.

I'm not necessarily arguing there's shared etymology, but consider 'for the nonce' - it's not merely a made up word used exclusively in cryptography.

Re: GCHQ Cracks Frank Sidebottom's Codes

#38

Post by willyt »

dtf wrote: post #28
cortesoft wrote: post #8

Earlier quoted context omitted.

Nonce is short for "number used only once"

Once is from the Middle English "anes", meaning "one". Nonce is from "then anes", meaning "the one". The "-n" got smooshed into the latter word, to become "nonce", rather like "an ewt" became "newt".

It’s also UK slang for peadophile, so be careful that everyone understands you are talking about cryptography not sex offenders if you use the word in public as there could be a nasty misunderstanding!

Re: GCHQ Cracks Frank Sidebottom's Codes

#39

Post by mattlondon »

cortesoft wrote: post #8
brad0 wrote: post #4

Earlier quoted context omitted.

Is gibberish called nulls or nonces? I forget.

Nonce is short for "number used only once"

It is also the word for a paedophile which is pretty unfortunate.

https://en.oxforddictionaries.com/definition/nonce

Re: GCHQ Cracks Frank Sidebottom's Codes

#40

Post by ColinWright »

benj111 wrote: post #30
krackers wrote: post #22

Earlier quoted context omitted.

Does code cracking still work in the era of modern cryptography? I thought that cryptosystems like AES and others were essentially impossible to crack if implemented right. What role do codebreakers play these days?

Theres still room for users to 'mess up' though. I believe allied code cracking in WW2 was helped by one wireless operator habitually ending their transmission "Heil Hitler" or something.

Also ...

German Enigma operators in WW2 were told always to send a certain number of messages per day to make it harder to perform traffic analysis. One bored operator sent a message composed entirely of "W" repeated 4000 times (or so).

One on-the-ball analyst noticed a message that had no "W"s in it, and deduced what had been sent[0]. That allowed the daily settings to be cracked, and thus all messages for that day.

[0] Enigma has a weakness in that no letter can be encrypted as itself[1].

[1] Enigma is effectively a "one-time-pad" where the pad is a pseudo-random sequence determined by the daily settings.

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