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Why do people keep repeating this trope that it's only a matter of time before encryption will be broken? Use a Diffie-Hellman style protocol to create and exc
by mpyne 13y ago
Why do people keep repeating this trope that it's only a matter of time before encryption will be broken?
Use a Diffie-Hellman style protocol to create and exchange a secret key for each session, use AES-256 if you're ultra-paranoid, then forget the session key. It even works today, and there are no known attacks against AES that can reduce the work enough to beat the heat death of the universe.
- merlincorey 13y agoI'll bite. Because we can't really predict the future and some far-fetched science-fiction sounding things such as quantum computers and future advancements we can't currently conceive of may completely and utterly change that, perhaps even overnight. From a paranoid security point of view, it's definitely a bad idea to assume your cryptography is perfect and always will be.
- mpyne 13y agoAnd from a paranoid physical security point of view it's definitely a bad idea to assume I would survive my car trip to the grocery store every week.... I do it anyways, as it's still much better than the alternatives.
- merlincorey 13y agoI believe this a logical fallacy. I didn't argue that due to said paranoia one should not engage in cryptography, any more than I would argue that one should not drive their car to the grocery store every week. I'm talking about complacency, and how it's a better idea for us to assume that sooner or later (if not currently) our best-known cryptography will be broken. If I recall correctly, in 2008, Simple Nomad[1] told us to consider PGP broken by the government. He wasn't saying it is... just we should consider it as such and find something better, before it's too late. [1] http://www.youtube.com/watch?v=N9AKpHtgpoM http://www.youtube.com/watch?v=N9AKpHtgpoM
- mpyne 13y agoAnd if I just told you to assume AES is broken by the government and find something better, would that be all the incitement you need? Or would you want actual evidence that at least hints it's probably instead of just assumptions?
- merlincorey 13y agoYou're missing the point. I already am thinking of it as broken, even without evidence, because I want to look ahead. This doesn't mean I don't use cryptography "because it's broken", it means I don't trust it as if it wasn't broken. Also, to be a bit unfair, I have no idea who you are, but I know who Simple Nomad[1] is. If Simple Nomad told me the government had definitely owned PGP, AES, or anything else of that nature I'd be very concerned, no evidence necessary. The implication is that he already has the evidence, but maybe can't share it with me. Or he's really drunk and messing with me.... either way, good times ahead! [1] http://www.soldierx.com/hdb/Simple-Nomad http://www.soldierx.com/hdb/Simple-Nomad > He has spoken at DefCon, BlackHat, ^Shmoocon^, and ToorCon, and he is known for his somewhat paranoid mindset.
- Natsu 13y agoThe problem with cryptography is that you only have to be wrong once.
- mpyne 13y agoThat's also the problem with switching to a new and untested solution. You only get to be wrong once. Is there any symmetric cypher with more cryptanalytic effort put into than AES? Is there even one? You switch to something else out of paranoia and you could easily switch to something with a theoretical backdoor that NSA has already identified and exploited (after all, they're "10-20 years ahead of us", right?).
- rsync 13y agoUnless it's a one time pad with good RNG. In that case it is indeed a good idea to assume your cryptography is perfect and always will be.
- merlincorey 13y agoJust don't lose the key... As I'm sure I don't have to tell you. What book would you use? That's how "they" used to do it.
- lotsofcows 13y agoPerfect? Two people know the key.
- jjoonathan 13y agoWhat about quantum computation? My (only slightly informed) understanding is that quantum computing's greatest strength lines up perfectly with the problem of brute-forcing encryption.
- tptacek 13y agoQuantum computing is a threat to RSA, DH, DSA, EDH, and ECDSA, but not to AES.
- Dylan16807 13y agoThe question then becomes how you're going to establish an AES key across a public channel without using quantum-vulnerable algorithms.
- tptacek 13y agoPresumably, you swap RSA for a code-based cryptosystem; the TLS structure itself could probably remain intact.
- quotemstr 13y agoWhat does a "code-based cryptosystem" mean? You can approximate asymmetric cryptography using something like Kerberos, but these schemes requires a trusted third party.
- tptacek 13y agoYou seem to be under the misapprehension that quantum computing threatens all asymmetric cryptosystems. It doesn't. McElice is an example of an asymmetric scheme that uses binary error correcting codes as its trapdoor function, rather than discrete logs.
- betterunix 13y agohttps://en.wikipedia.org/wiki/Post-quantum_cryptography https://en.wikipedia.org/wiki/Post-quantum_cryptography
- deleted 13y ago[deleted]
- clarkm 13y agoThis is basically what OTR messaging does. But you're still vulnerable to man-in-the-middle attacks when using DH, unless you're already on a secure channel. And the most common solution to authentication is SSL/TLS, which the defeats the purpose of the whole thing. So we need to utilize other channels, like key-signing parties. Or, I suppose you can communicate using something like SRP to avoid this issue, though it sounds like a complicated layering of crypto that is destined to be screwed up at some point. However, this is what ZRTP does, and it seems to be pretty widely adopted.
- tsotha 13y ago>It even works today, and there are no known attacks against AES that can reduce the work enough to beat the heat death of the universe. Well, that's the problem isn't it? The known attacks aren't the ones you have to worry about. Nearly every form of cryptography to date was expected to last longer than it actually did. I would not be at all surprised to find AES-256 broken before I'm on the wrong side of the grass.