LLMs won't break symmetric crypto • Hacker News Board

Re: LLMs won't break symmetric crypto

#61

Post by mindwok » Thu, Aug 06, 2026, 4:22 AM UTC

zkmon wrote: post #9

Cryptographic systems are based on 1) mathematical impossibility of reversing some integer/mod calculation, 2) time required for a brute force attack, 3) correctness of algorithms and code used in implementations. The last part (algorithms and code) is where LLMs have a chance. The first one is not similar to the mathematical breakthroughs LLMs are making recently. There is a loss of information in mods and integer c…

> mathematical impossibility of reversing some integer/mod calculation > There is a loss of information in mods and integer computations making them one-way

That's not correct. Trapdoor functions aren't one way because they destroy information, and if they were they wouldn't be very useful because you wouldn't be able to go back the other way (i.e. decrypt the text). You'd end up with many possible inputs for a given output, like a hash.

Re: LLMs won't break symmetric crypto

#62

Post by tptacek » Thu, Aug 06, 2026, 4:23 AM UTC

stingraycharles wrote: post #54

tptacek wrote: post #45

Earlier quoted context omitted.

Symmetric cryptography isn't based on complicated math the way asymmetric cryptography it is. The right way to think about symmetric cryptography is that the core hard problem is simply making PLAINTEXT XOR KEY work, efficiently, with a key that repeats.

Isn’t another aspect of it that it’s sufficiently random / unrecognizable, for example? I’m very much aware of the differences between symmetric and asymmetric encryption, and realize that symmetric encryption is much simpler, but I figure that if there are weaknesses to be found in algorithms such as md5, then surely there are also potential weaknesses in symmetric encryption algorithms? Now I’m not saying that this…

You can certainly invent a weak block cipher, and an LLM would probably do a decent job spotting e.g. something that could be productively attacked with a SAT solver.

Re: LLMs won't break symmetric crypto

#63

Post by tptacek » Thu, Aug 06, 2026, 4:25 AM UTC

volkercraig wrote: post #53

sghiassy wrote: post #6

Earlier quoted context omitted.

Thank you I guess I only know asymmetric cryptography. I should learn more about symmetric… Anyone care to boil it down for me :) Edit: Isn’t this just advanced static analysis of any code base?

There is already a mathematically secure algorithm for securing a message: One Time Pad. The problem is that OTP requires that the length of the key and the length of message must be the same, which is inconvenient for large amounts of data. So the solution is to find algos that let you use a smaller key, but the side effect is that by pigeonhole principle, your keyspace is smaller than the message space, so it MUST…

It's inconvenient for any amount of data, because it essentially begs the question; if you can securely transmit N bytes of key pad to a counterparty, just use that mechanism to transmit N bytes of plaintext instead.

Re: LLMs won't break symmetric crypto

#64

Post by zkmon » Thu, Aug 06, 2026, 4:26 AM UTC

deepsun wrote: post #55

zkmon wrote: post #9

Cryptographic systems are based on 1) mathematical impossibility of reversing some integer/mod calculation, 2) time required for a brute force attack, 3) correctness of algorithms and code used in implementations. The last part (algorithms and code) is where LLMs have a chance. The first one is not similar to the mathematical breakthroughs LLMs are making recently. There is a loss of information in mods and integer c…

> mathematical impossibility of reversing some integer/mod calculation No, there's no proof that most crypto "calculations" are impossible to reverse. That's why algorithms got weakened by researchers regularly. As of now, it's totally possible someone finds an algorithm to break a next one tomorrow. They just haven't found it yet.

Talking about proofs, there is no proof that just because AI found counter example for a conjecture, it can break math behind cryptography The belief that "if it did A and B it can do C,D,E ,,,Z" is what is driving the current AI hype.

Re: LLMs won't break symmetric crypto

#65

Post by kadoban » Thu, Aug 06, 2026, 4:30 AM UTC

tptacek wrote: post #60

kadoban wrote: post #57

Earlier quoted context omitted.

> with a key that repeats There's a _lot_ hiding in that, all of the interesting stuff for security and potential breaks. So...yeah it is based on complicated math, it's just in that bit instead of the xor. Even the xor is a bit of a fudge, but probably close enough.

There's a lot of basic computer science hiding in it that's been remarkably stable for generations of computer scientists, which is not something you can say about asymmetric cryptography.

Is there? Like...kind of, but on the face of it I'd say about the same amount in both. If you look back at DES there's a _lot_ in common with modern ciphers, but like, RSA is still in use and that's old as shit.

I think you're right if your point is that we're more likely to see big breaks in asymmetric crypto, but it's kind of based on vibes to me, it's not really clear that it's provable in any way with anything like our current understanding.

Re: LLMs won't break symmetric crypto

#66

Post by [deleted] » Thu, Aug 06, 2026, 4:32 AM UTC

arberx wrote: post #13

LLMs will accelerate math research, increasing understanding in areas like quantum which will eventually lead to breakthroughs that will break most standard asymmetric encryption algorithms with the side effect of breaking crypto

[deleted]

Re: LLMs won't break symmetric crypto

#67

Post by SKYNET800 » Thu, Aug 06, 2026, 4:41 AM UTC

[flagged]

Re: LLMs won't break symmetric crypto

#68

Post by danielmarkbruce » Thu, Aug 06, 2026, 4:47 AM UTC

insanitybit wrote: post #58

danielmarkbruce wrote: post #56

Earlier quoted context omitted.

I can't tell if you are serious at this point. I literally say, twice, that I'm not talking about a language model. And I also say the model would predict the key...not the plaintext.

And I'm asking you to describe the model.

Ouput: 128 logits. Input: maybe 10 samples of plaintext,ciphertext (using the same key), so maybe a 2560 length tensor. Loss function: binary cross entropy on the true key bits. Architecture: anyone's guess.

If you were in a place to debate this, you would have known the above (or something similar) is what I was suggesting when i said train on plaintext, cipertext -> key, and you'd have some deep mathematical insight as to why no architecture known is likely to work. And you would also know I wouldn't be here talking to you about it if I really had a solid idea of an architecture that is likely to work.

Re: LLMs won't break symmetric crypto

#69

Post by j16sdiz » Thu, Aug 06, 2026, 4:49 AM UTC

zkmon wrote: post #9

Cryptographic systems are based on 1) mathematical impossibility of reversing some integer/mod calculation, 2) time required for a brute force attack, 3) correctness of algorithms and code used in implementations. The last part (algorithms and code) is where LLMs have a chance. The first one is not similar to the mathematical breakthroughs LLMs are making recently. There is a loss of information in mods and integer c…

> 1) mathematical impossibility of reversing some integer/mod calculation

You are describing asymmetric encryption. This article was talking about symmetric encryption.

Symmetric encryption is generally considered much harder to break than asymmetric encryption

Re: LLMs won't break symmetric crypto

#70

Post by cootsnuck » Thu, Aug 06, 2026, 4:53 AM UTC

SKYNET800 wrote: post #67

[flagged]

Please consider taking a break from your use of LLMs. You are clearly deep in the throes of AI psychosis and need to talk to people you trust in your life instead of the chatbots.