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Discovering Cryptographic Weaknesses with Claude

anthropic.com

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Re: Discovering Cryptographic Weaknesses with Claude

#181

Post by cousinbryce »

Exoristos wrote: post #143
Chabsff wrote: post #136

Earlier quoted context omitted.

I almost entirely agree with this. However, after coding quite a few large projects with LLM assistance, I can say with certainty that there is some form of "art" at play with regards to structuring requests for LLMs. However, this "art" is not so much about how to present a given request to the LLM, but rather guestimating what the scope of the next chunk of work should be to balance getting as much out of the model…

Hypothesis: Good Jenga players will make good coding-assistant prompters.

This happened to me last night. Did a lazy prompt and the tower started to lean dangerously

Re: Discovering Cryptographic Weaknesses with Claude

#182

Post by adrian_b »

vessenes wrote: post #103
adrian_b wrote: post #57

Earlier quoted context omitted.

It should be noted that the attack is not only an attack against a weakened AES, but it is also a chosen-plaintext attack. It is standard in cryptography to analyze ciphers under this kind of attack, which is stronger than normal attacks, because a cipher that resists to a stronger attack will also resist to weaker attacks, so using the strongest possible attack increases the confidence in a cipher. While using the s…

I do not believe that chosen plaintext attacks are obsolete. Any time you have an encrypting oracle setup in which the scheme itself does not require some sort of modification of the plaintext itself, you can reach for a chosen plaintext attack. I believe mitigations are known and can be applied or required in standards, but I don't think it's a 'dead' area of cryptanalytic research -- there's so much devil in the de…

Chosen plaintext attacks can work against things like hashing algorithms.

But with methods of encryption like AES GCM or any other based on the counter mode, an encrypting oracle does not encrypt the text provided by the adversary.

It encrypts a sequence of numbers that cannot be influenced in any way by the adversary, which is then used as an encryption mask for the text chosen by the adversary.

No matter what text is chosen by the adversary, it cannot obtain any other information from the oracle except which was the encryption mask.

Therefore, the chosen plaintext attack is converted into a much weaker known plaintext attack, because in the worst case the adversary knows both the initial counter value, i.e. the sequence of numbers, and the encryption mask generated by encrypting that sequence.

Only if AES were used in a hashing algorithm, instead of being used for encryption, while using a dedicated hash function for hashing, then AES would be exposed to a chosen plaintext attack, when the adversary would be able to provide the text to be hashed and the oracle would give the hash value.

IF AES were used in obsolete modes of operation for encryption, like AES-CBC, then it would be exposed to chosen plaintext attacks.

Re: Discovering Cryptographic Weaknesses with Claude

#183

Post by heaney-555 »

nojs wrote: post #141
heaney-555 wrote: post #42

Earlier quoted context omitted.

If a Chinese model can do it for $1-10K, then why hasn't one? Why have all the mathematical (and now cryptographic) breakthroughs come from OpenAI and Anthropic? Is it possibly because the Chinese models are so benchmaxxed they can't make novel discoveries?

For one thing they are extremely GPU constrained due to export controls, so it’s unlikely a priority compared to training

So why didn't anyone with access to Chinese models do it. They're open-source, right? So you're telling me no-one could afford $1K to solve a problem like this?

(hint: it's BS, the Chinese models either can't do it or can at the same or greater cost)

Re: Discovering Cryptographic Weaknesses with Claude

#184

Post by ameliaquining »

vrighter wrote: post #160
ameliaquining wrote: post #39

Earlier quoted context omitted.

That last sentence is not true; we have gotten much closer to building a quantum computer that can run Shor's algorithm. Organizations like Google and Cloudflare have declared a 2029 deadline to completely stop depending on the security of pre-quantum algorithms; hitting that deadline is going to cost a lot of engineering resources, but they're paying that cost because they think there's too great a chance that natio…

I don't trust promises from the ones who stand to gain from people believing them before they are delivered. Yes they claim it's jsut a couple of years out... we'll see then

Are you saying we shouldn't trust cryptographers, because there'll be more demand for their services if we need to urgently migrate to post-quantum algorithms? That seems a very radically-skeptic perspective that makes it hard to know anything, and I doubt any serious engineer applies it in the general case. Or were you talking about someone else?

In any rate, nobody (or at least none of the people I've heard from) is claiming we'll definitely have CRQCs by 2029. They're saying there's a real chance that we will, and that that means now's the time to pull the trigger on post-quantum migrations; if we wait for certainty, it'll be too late. Quoting Valsorda from the post I linked above (which I strongly recommend reading in full):

> If you are thinking “well, this could be bad, or it could be nothing!” I need you to recognize how immediately dispositive that is. The bet is not “are you 100% sure a CRQC will exist in 2030?”, the bet is “are you 100% sure a CRQC will NOT exist in 2030?” I simply don’t see how a non-expert can look at what the experts are saying, and decide “I know better, there is in fact > Put another way, even if the most likely outcome was no CRQC in our lifetimes, that would be completely irrelevant, because our users don’t want just better-than-even odds of being secure.

Re: Discovering Cryptographic Weaknesses with Claude

#185

Post by ameliaquining »

quotemstr wrote: post #41
JuniperMesos wrote: post #20

Earlier quoted context omitted.

The classical cipher component is additonal complexity in the protocol and maybe some meaningful amount of additonal time to compute and key data to store/transmit, is it not? I can see why we'd like to avoid effectively encrypting the same data twice with different protocols, one of which is known to be vulnerable to quantum computer based attacks.

Classic ciphers are damn fast and small compared to PQC. If you're doing PQC anyway , doing classical cryptography at the same time has negligible cost. That makes attempts to push PQC-only modes super suspicious to me. Smells like Dual_EC_DRBG.

I recommend reading https://keymaterial.net/2025/11/27/ml-kem-mythbusting/, which explains (1) why it's not possible for ML-KEM (the thing most people are using for post-quantum encryption) to be backdoored the way Dual_EC_DRBG was, and (2) some of the reasons some people don't like hybrids, not all of which are good but none of which should serve to undermine confidence in ML-KEM's security.

Re: Discovering Cryptographic Weaknesses with Claude

#186

Post by charcircuit »

TeMPOraL wrote: post #158
charcircuit wrote: post #97

Earlier quoted context omitted.

What do you mean how you never write? You can just write what for want to say instead of saying it out loud. It is not a special skill, it's no different than how you write a message, just that you don't hit backspace to go back and correct things.

> it's no different than how you write a message, just that you don't hit backspace to go back and correct things. Yes, that. If you do that when writing to another person, you come off as blabbering, incoherent moron. Fortunately, very few people do that, because communicating with people who write like they talk is incredibly hard. I'd worry about trying to do this on purpose; feels like the kind of "learning" that…

>I'd worry about trying to do this on purpose

You already have to juggle multiple writing styles between different people and use cases. It is easy to avoid submitting a pure stream of thought if you are writing a formal letter.

>there's an append-only procedure for fixing that, which I just demonstrated.

LLMs can figure out most typos on your own.

>you have to wait for LLM to finish.

I don't think any coding harnesses work like this. They let you send more messages to steer the model while it's working.

Re: Discovering Cryptographic Weaknesses with Claude

#187

Post by ameliaquining »

connorboyle wrote: post #78
_dwt wrote: post #22

I find that some of my friends and acquaintances have gotten obsessed with prompting style, "prompt engineering", which skills to use, which skills to build, "context engineering", and a billion other variations on "how to write smart things so the model does good". Friends, look at the prompts that Anthropic's own people are putting into the machine: > A few hours after the first message, we found that Claude was st…

Been skeptical for quite some time that "using AI" is a real skill/genuine field of expertise. I think I need to start sharing that skepticism more loudly and publicly! (I'll caveat that by saying I think machine learning fundamentals are useful for evaluating any estimator. And an ML background can be good to give one an appreciation of how hard some tasks are to estimate, such as machine translation, summarization,…

It definitely was a real skill; there was a time when you could get impressive results out of frontier LLMs if you knew the most advanced tricks for prompting them, but not if you just told them "hey solve this problem for me".

However, it's not a sustainable skill, because the labs care a lot about making "hey solve this problem for me" work well, and so put out models that are better and better at working with unsophisticated prompts over time.

There's an excellent piece about this, but it's unfortunately paywalled: https://www.theargumentmag.com/p/can-you-tinker-your-way-out...

Re: Discovering Cryptographic Weaknesses with Claude

#188

Post by cxseven »

staticshock wrote: post #47

When high quality effort is applied to a tool, such as AES or the linux kernel, we intuit that it "hardens" the tool. That is, it makes the tool more correct, more resilient, less assailable, etc. Similarly, when effort is applied to an open problem, such as the Riemann hypothesis or P v NP, without progress, it "hardens" the problem: it makes the problem feel more daunting to whoever takes a stab at it next. Andrew…

1. Some of the "AI" proofs applied existing human work from lesser-known papers. AI proofs could solve the long-standing problem in math of almost all attention concentrating on less than 1% of authors. Human effort from the other 99% would have otherwise been wasted, which AI can rescue and give credit to thanks to its superhuman ability to match patterns across reams of text.

Humans may remain superior in spatial / non-verbal reasoning for a while longer yet, and, in the meanwhile, computers may aid us in collaborating to put that to use better.

2. AI-assisted, computer-verified proofs could further democratize mathematics by reducing the power of connections to get a reviewer to look at a journal submission. We can then also decouple the two tasks of

  a. Verifying a statement is true
  b. Explaining it
3. Searching for previous work and finding the edges of human knowledge are now easier. And we can leap across tedious terrain that the machine has the patience to plod through to find more interesting questions.

Re: Discovering Cryptographic Weaknesses with Claude

#189

Post by vrighter »

ameliaquining wrote: post #184
vrighter wrote: post #160

Earlier quoted context omitted.

I don't trust promises from the ones who stand to gain from people believing them before they are delivered. Yes they claim it's jsut a couple of years out... we'll see then

Are you saying we shouldn't trust cryptographers, because there'll be more demand for their services if we need to urgently migrate to post-quantum algorithms? That seems a very radically-skeptic perspective that makes it hard to know anything, and I doubt any serious engineer applies it in the general case. Or were you talking about someone else? In any rate, nobody (or at least none of the people I've heard from) i…

i don't trust google

Re: Discovering Cryptographic Weaknesses with Claude

#190

Post by salawat »

AsyncBanana wrote: post #74
_dwt wrote: post #22

I find that some of my friends and acquaintances have gotten obsessed with prompting style, "prompt engineering", which skills to use, which skills to build, "context engineering", and a billion other variations on "how to write smart things so the model does good". Friends, look at the prompts that Anthropic's own people are putting into the machine: > A few hours after the first message, we found that Claude was st…

"prompt engineering" in general just boggles my mind. It is amazing how all of this investment has just created software that doesn't follow instructions well.

And lies to boot. No, I won't take the bait of "Models can't lie, they don't have intent" either. One can lie by omission, and just watching thinking traces is more than enough to demonstrate the machine is more than happy to deceive end users if it's training set, RLHF, or other harness quirks tell it to. Only difference is that now you don't have code that's as easy to track down to implement the deception as a red flag.

Made me sick the first time I ran a model on my machine. I'll take honest malware over a "well meaning liar" of an LLM any day.

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