Adi Shamir's Cube Attacks
At this moment, Adi Shamir is giving an invited talk at the Crypto 2008 conference about a new type of cryptanalytic attack called “cube attacks.” He claims very broad applicability to stream and block ciphers.
My personal joke — at least I hope it’s a joke — is that he’s going to break every NIST hash submission without ever seeing any of them. (Note: The attack, at least at this point, doesn’t apply to hash functions.)
EDITED TO ADD (8/19): AES is immune to this attack — the degree of the algebraic polynomial is too high — and all the block ciphers we use have a higher degree. But, in general, anything that can be described with a low-degree polynomial equation is vulnerable: that’s pretty much every LFSR scheme.
EDITED TO ADD (8/19): The typo that amused you all below has been fixed. And this attack doesn’t apply to any block cipher — DES, AES, Blowfish, Twofish, anything else — in common use; their degree is much too high. It doesn’t apply to hash functions at all, at least not yet — but again, the degree of all the common ones is much too high. I will post a link to the paper when it becomes available; I assume Adi will post it soon. (The paper was rejected from Asiacrypt, demonstrating yet again that the conference review process is broken.)
EDITED TO ADD (8/19): Adi’s coauthor is Itai Dinur. Their plan is to submit the paper to Eurocrypt 2009. They will publish it as soon as they can, depending on the Eurocrypt rules about prepublication.
EDITED TO ADD (9/14): The paper is online.