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“This telegram must be closely paraphrased before being communicated to anyone”

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Re: “This telegram must be closely paraphrased before being communicated to anyone”

#51

Post by philwelch »

maxbond wrote: post #24

ETA: Note that I appear to have been mistaken about the connection to ENIAC. Note that it is equally dangerous to send paraphrased messages using the same key (which is called sending messages "in depth"). This was used to crack the Lorenz ("Tunny") cipher. Interestingly Bletchley Park hadn't gotten their hands on a Lorenz machine, they cracked it based on speculation. And it lead to the development of the first tube…

This is the first I’ve heard of Colossus influencing the ENIAC. I was under the impression that Colossus was so secret that ENIAC was designed independently and (falsely) touted as the first tube computer prior to Colossus’ existence being declassified. I’m not sure if I’m misremembering that though.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#52

Post by BigJono »

> In this process, deletion rather than expansion of the wording of the message is preferable, because if an ordinary message is paraphrased simply by expanding it along its original lines, an expert can easily reduce the paraphrased message to its lowest terms, and the resultant wording will be practically the original message.

This bit has me perplexed. If you had a single message that you wanted to send multiple times in different forms, wouldn't compressing the message exponentially limit possible variation whereas expanding it would exponentially increase it? If you had to send the same message more than a couple of times I'd expect to see accidental duplicates pretty quickly if everyone had been instructed to reduce the message size.

I guess the idea is that if the message has been reduced in two different ways then you have to have removed some information about the original, whereas that's not a guarantee with two different expansions. But what I don't understand is that even if you have a pair of messages, decrypt one, and manage to reconstruct the original message, isn't the other still encrypted expansion still different to the original message? How does that help you decrypt the second one if you don't know which parts of the encrypted message represent the differences?

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#53

Post by beerws »

Ironically, stating this at the beginning of telegram would precisely cause what it seeks to prevent (vulnerability to known plaintext attacks).

Which makes me wonder: how many permutations of this rule could be conceived (and needed) that on the one hand would keep the point clear to the receiver, but on the other hand prevent such attacks?

In any case the best option is to not have (to repeat) this rule inside messages.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#54

Post by tripplyons »

Stevvo wrote: post #44
maxbond wrote: post #24

ETA: Note that I appear to have been mistaken about the connection to ENIAC. Note that it is equally dangerous to send paraphrased messages using the same key (which is called sending messages "in depth"). This was used to crack the Lorenz ("Tunny") cipher. Interestingly Bletchley Park hadn't gotten their hands on a Lorenz machine, they cracked it based on speculation. And it lead to the development of the first tube…

An interesting quirk in Ethereum is that a contract address is determined by deployer address + nonce. So, you can send ETH to a contract that does not exist, then later deploy a contract there and recover it.

It is also the same address on many forks of Ethereum, which has led to some strange circumstances when Optimism sent tens of millions of dollars to a smart contract address on the wrong blockchain, and a hacker was able to create a smart contract they controlled using the same address on the blockchain it was accidentally sent to and steal the funds.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#55

Post by notherhack »

justsomehnguy wrote: post #50
anon_cow1111 wrote: post #22

Earlier quoted context omitted.

Might be unrelated in this example, but when a message is written in a lazy ROT13-like cypher, the letter e becomes a notorious rat that allows anyone to break the entire thing in very little time. Randomizing/obfuscating the letter case might buy you a little time, though I think it's something else entirely here.

Zvtug oR haeRyngRq va guvf RknzcyR, ohg juRa n zRffntR vf jevggRa va n ynml EBG13-yvxR plcuRe, guR yRggRe R oRpbzRf n abgbevbhf eng gung nyybjf nalbaR gb oeRnx guR RagveR guvat va iRel yvggyR gvzR. Enaqbzvmvat/boshfpngvat guR yRggRe pnfR zvtug ohl lbh n yvggyR gvzR, gubhtu V guvax vg'f fbzRguvat RyfR RagveRyl uReR.

V guvax gur vqRn jnf gb fcyvg guR uvtu seRdhrapl "r" gb gjb qvssReRag flzobyf r naq R ng yRffRe serdhrapvRf. Fvzcyl ercynpvat nyy r'f jvgu R qbrfa'g qb gung.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#56

Post by maxbond »

philwelch wrote: post #51
maxbond wrote: post #24

ETA: Note that I appear to have been mistaken about the connection to ENIAC. Note that it is equally dangerous to send paraphrased messages using the same key (which is called sending messages "in depth"). This was used to crack the Lorenz ("Tunny") cipher. Interestingly Bletchley Park hadn't gotten their hands on a Lorenz machine, they cracked it based on speculation. And it lead to the development of the first tube…

This is the first I’ve heard of Colossus influencing the ENIAC. I was under the impression that Colossus was so secret that ENIAC was designed independently and (falsely) touted as the first tube computer prior to Colossus’ existence being declassified. I’m not sure if I’m misremembering that though.

I think you're right, my mistake. I didn't find anything definitive but given they were developed around the same time by (on cursory inspection) different people and that Colossus was as secret as you say (it wasn't declassified until the 70s), it does seem unlikely. I thought that had been mentioned in a Computerphile/Numberphile video on the topic but I must be mistaken.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#57

Post by andoma »

maxbond wrote: post #24

ETA: Note that I appear to have been mistaken about the connection to ENIAC. Note that it is equally dangerous to send paraphrased messages using the same key (which is called sending messages "in depth"). This was used to crack the Lorenz ("Tunny") cipher. Interestingly Bletchley Park hadn't gotten their hands on a Lorenz machine, they cracked it based on speculation. And it lead to the development of the first tube…

I visited Bletchley Park museum this summer when in London. Can recommend and it's also really easy to get there; just a 50 minute train ride from London Euston station, and 5 minute walk to the museum. Entire family enjoyed the museum (have two teenage kids). There is also the "National Museum of Computing" located next to it which contains the Bombe, Collosus and related equipment. As I understand it most (or all?) of the original hardware was destroyed after the war to avoid leaking any information about the British code breaking skills. Thus, the machines on display are replicas, but should be fully working.

The computer museum also exhibits post-war computers all the way to modern machines. I'd say that museum is more for the geeks while the Bletchley Park museum is definitely worth a visit even if you're not into computers.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#59

Post by pyuser583 »

Known-plaintext attacks aside, if you're going to compress text, it must be done before encryption.

I don't know if compression offers much protection against plaintext attacks.

This also makes me wonder how helpful AI is in such situations. AI is essential an extremely effective, lossy, compression algorithm.

Re: “This telegram must be closely paraphrased before being communicated to anyone”

#60

Post by hcs »

pyuser583 wrote: post #59

Known-plaintext attacks aside, if you're going to compress text, it must be done before encryption. I don't know if compression offers much protection against plaintext attacks. This also makes me wonder how helpful AI is in such situations. AI is essential an extremely effective, lossy, compression algorithm.

Compression + encryption can be dangerous if the compression rate is exposed somehow (between messages or within packets of a message).

> we show that it is possible to identify the phrases spoken within encrypted VoIP calls when the audio is encoded using variable bit rate codecs

https://crypto.stackexchange.com/a/2188

See also https://breachattack.com/ when the plaintext is partially attacker-controlled.

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