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Forging 1024-bit RSA signatures in nearly SNFS time [pdf]

40 points • by int0x29 • today at 2:26 PM • 6 comments • view on HN

https://arstechnica.com/security/2026/09/theres-a-new-way-to...


Comments

tptacek • today at 6:56 PM

The most important thing to know about this work, which is awesome, is that it relies on access to a raw RSA oracle, where you have a public key and an API that allows you to directly do RSA operations with the corresponding key. The idea is that you then lose access to the oracle, and thus to the private key, but you've gained enough information from your session with the oracle to make forgeries in the future.

So it's not a straightforward general-purpose RSA-1024 signature break; it's pretty situational. The paper goes into detail (in section 5) about how those situations can emerge in practical scenarios.

➕ show 2 replies
nk_kolja • today at 8:34 PM

I was unaware of snfs algorithms for generic moduli and/or signatures. Very nice. The theoretical result is purely due to the 2007 Joux et al. paper. What’s new is the implementation and the 1024-bit rsa signature forgery.

Also no ai, so we can expect some speedups soon.

I really didn’t expect rsa to be targeted so much this year. Hope that these results will motivate people to pursue algorithmic improvements!

benmmurphy • today at 9:48 PM

nice poem at the end of the paper

keeganryan • today at 7:09 PM

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