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“This destroys the RSA cryptosystem”

279 points| renaudg | 5 years ago |eprint.iacr.org | reply

146 comments

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[+] Centigonal|5 years ago|reply
The author of this paper is Claus P. Schnorr[1], of Schnorr signature fame.

The paper has almost the same title as a 2017 draft paper[2] of his. The “This destroyes the RSA cryptosystem” quote is not in the linked paper abstract. This seems fishy.

[1] https://en.wikipedia.org/wiki/Claus_P._Schnorr

[2] https://www.math.uni-frankfurt.de/~dmst/research/papers/SVP9...

[+] yesenadam|5 years ago|reply
> The paper has the same title as a 2017 draft paper

Not quite the same title. He has papers with similar titles since at least 2010.

I wanted to say thanks - this document linked to on his wikipedia page was unexpectedly fascinating! NSA, patents, conspiracies..

https://marc.info/?l=cypherpunks&m=95280154624588&w=2

[+] tveita|5 years ago|reply
So are you saying I shouldn't run out and short the RSA stock? :)

I was curious about the submission process for ePrint, it looks like there is supposed to be some vetting, even though it is explicitly not fact checked or peer reviewed. You do get papers from cranks and blockchainers but presumably Schnorr doesn't fall into those categories.

https://eprint.iacr.org/about.html

[+] detaro|5 years ago|reply
EDIT: that draft appears in clearer sources with the same spelling, disregard below...

He also apparently misspelled(?) his own name. It's "Claus-Peter" (also on other publications), not "Claus Peter". agreed, seems odd.

[+] cnlp100|5 years ago|reply
It is strange, perhaps a pdf reader exploit?
[+] hyper_reality|5 years ago|reply
This is being discussed in CryptoHack Discord. We are struggling to understand the paper, it is written in a very dense style and the difficulty is compounded by the fact that lattice problems can be a challenging topic even for cryptographers.

Either way, we think that the title "this destroys the RSA cryptosystem" is sensationalistic and probably incorrect. It is presumably based on the fact that the paper claims to reduce some forms of integer factorisation to a lattice problem which can be solved in polynomial time. However, whether this technique applies in the general case to RSA moduli is not argued here and the claim seems to be premature.

[+] 7800|5 years ago|reply
It actually states, “This destroyes the RSA cryptosystem.”

Seems a bit like the way an old pirate might speak, or at least someone hundreds of years old.

[+] bjeds|5 years ago|reply
?

This is discussed here, at Hacker News. It's also discussed at many other places on the internet. :-)

Why is this chat room you mention relevant? And who are "we" you speak of? You are presenting yourself as some kind of authority, but you need to back that claim up.

[+] marktangotango|5 years ago|reply
Well, that's certainly provacative, can the title be updated to the title of the paper and year (2019)?

"Factoring Integers by CVP and SVP Algorithms"

[+] OJFord|5 years ago|reply
It is a direct quote from the end of the abstract. The paper could hardly be titled that way. It is editorialising and thus against the guidelines.. but it's reasonable IMO.

It would hardly be getting such attention with the original title, and that attention is either what it needs, or what it needs to promptly dispell it.

[+] baby|5 years ago|reply
Can we not do this, your suggestion prevents anyone from understanding what is at play here.
[+] elmo2you|5 years ago|reply
This last sentence of the abstract, "This destroyes the RSA cryptosystem", does not appear on the abstract of the actual PDF (which also appears to be dated).

How does it destroy RSA? Under what conditions? That claim sounds rather broad and definitely bold, to say the least.

[+] gpm|5 years ago|reply
> work in progress 31.10.2019

^ Date on the pdf

[+] jeofken|5 years ago|reply
Would someone competent in cryptography please explain this to a “regular” programmer?
[+] dfabulich|5 years ago|reply
RSA is a "public key" cryptography system, where you have a public key that everyone's allowed to know, and a private key that you keep secret. Anyone can use the public key to encrypt messages, but you need the private key to decrypt messages.

(You can also use it for digital signatures, where you provide a copy of the message and also "encrypt" the message with the private key; anyone can publicly decrypt it. If the "decrypted" message matches the original, then the signature proves that the message was signed by someone who has the private key.)

RSA works by starting with two large random prime numbers P and Q. You multiply P and Q to get a number M, and that number becomes part of the public key. An attacker who knows P and Q can compute your private key and decrypt your messages.

RSA assumes that it's computationally infeasible to factor M back into P and Q. It's supposed to be something like O(2^n), where n is the length of M.

A fast factorization algorithm breaks that assumption, allowing attackers to decrypt messages and forge digital signatures.

If Schorr has found an algorithm that does this, I would say it "destroyes the RSA cryptosystem."

(My guess: it probably doesn't work, because drafts of this paper have been out for a few years and the sky hasn't fallen yet.)

[+] pkulak|5 years ago|reply
Yeah, if this really is fast prime factoring, we're all in a lot of trouble.
[+] lquist|5 years ago|reply
Yes and if it is feasible given current computer architectures or requires significant advances in quantum algorithms/computers?
[+] nanis|5 years ago|reply
It looks like someone read the paper and came to the conclusion that this shortens the expected lifespan of RSA and submitted the paper to IACR. I doubt it was Schnorr himself who decided to make the sensationalist claim.

The final theorem in the paper is where the polynomial time claim is states. Can't quote it here because it would make no sense in isolation, but the math is readable and the claims should be independently verifiable.

[+] sjwalter|5 years ago|reply
If you've been following Schnorr's work, his pathway for the last decade can be summed up as thus:

* 2011, retires from work at RSA foundation

* 2015, publishes first version of this paper, stating, "This is a WIP".

* 2017, 2018, 2019: Publishes updates of this paper, still stating "This is a WIP". Paper mostly ignorred.

* 2021: Publishes this final update. Removes "WIP" marking. Adds sentence (verifiable in original paper), "This destroys RSA cryptosystems".

Whether or not it's true, the level of dismissal here is kinda insane. This guy has credibility up the wazoo. The paper is dense and beyond my understanding. But this guy ain't some crackpot, this isn't some out-of-nowhere change: He's been clear about his intent and goals for nearly a decade, and now he says it's achieved.

[+] randtrain34|5 years ago|reply
They only tested with numbers size of ~2^800, which is around 240 digits, but I believe (correct me if I'm wrong) there exists usages of RSA with over 600 digits, so it'll still take a massively long amount of time to factor those numbers...
[+] munchbunny|5 years ago|reply
Typical key lengths for RSA these days are 2048 and 4096 bits.

I don't know what that means for this paper, just happened to have those two key lengths off the top of my head.

[+] kaishiro|5 years ago|reply
Man, this is one of those HN pieces I open and immediately think "I'm not smart enough to understand any of this."
[+] gnulinux|5 years ago|reply
Can someone please correct me? We don't know polynomial CVP/SVP algorithms correct? In fact, isn't SVP an NP-Hard problem? Why would this "destroy" RSA?
[+] dleslie|5 years ago|reply
I'm not sure if this is the claim in the paper; but I'll try to explain in plain terms.

Let's say you have an algorithm that can solve NP-hard problems in polynomial time with an N% success rate.

What value of N makes the algorithm useful in practice depends on the practicality of its use as an attack against the NP-hard problem; there is an inflection point whereat the speed of the attack outstrips the speed at which the cypher can change secrets.

[+] BluSyn|5 years ago|reply
There's a difference between cryptography broken in "theory" and broken in "practice". Couldn't find anything relevant to that point in the paper. Who here is qualified to make that assessment?
[+] balupton|5 years ago|reply
I've gone ahead and updated the following wiki pages to get the right eyeballs on this: https://en.wikipedia.org/wiki/Integer_factorization https://en.wikipedia.org/wiki/RSA_(cryptosystem) https://en.wikipedia.org/wiki/Claus_P._Schnorr

Also cross-shared with Cloudflare's forum, as I believe they would be interested: https://community.cloudflare.com/t/this-destroys-the-rsa-cry...

[+] earonesty|5 years ago|reply
....and someone rolled back your edits. because it's not peer reviewed.
[+] ncann|5 years ago|reply
Obviously this went way over my head, but what is the claimed time complexity here?
[+] ramboldio|5 years ago|reply
"This proves the polynomial time bound."
[+] thomasahle|5 years ago|reply
It's hard to figure out what they are claiming, which makes the whole paper seem fishy.

On page 14 they seem to claim a factor 2 improvement in the exponent of the quadratic number field sieve, which might be better that the general sieve for some N, but is still worse asymptotically.

[+] olliej|5 years ago|reply
Given the claims I would have wanted the paper to include factoring for some of the known rsa public keys to demonstrate feasible time.
[+] intunderflow|5 years ago|reply
I agree, at this point I'm way out of my depth so I'm waiting for folks who know cryptography inside and out to give their comment