246 karma · joined February 7, 2014
This is a pretty interesting email chain and a fairly good case study for those of us who aim for zealous adherence to standards and rules vs. providing a practical and useful output for users. I know I tend to go zealous by default and often have to remind myself that I'm not just writing software to satisfy my own academic ego.
"For example, the current generation of chips (DDR SDRAM) has a refresh time of 64 ms and 8,192 rows, so the refresh cycle interval is 7.8 μs."
Sounds like your idea is already a thing! That's cool! Unfortunately it seems like the performance-cycle period tradeoff is difficult and Rowhammer is taking advantage of that.
Protecting subsets of memory is an interesting idea but what bits do you choose? What if I could Rowhammer the memory frame behind a COW page belonging to a setuid binary? I feel like it might be an all or nothing kind of thing in this situation. Who knows though, maybe there's merit in specifically protecting kernel owned frames, it's difficult to say for sure.
Am I missing some aspect of page mapping/cache management?
The backdoor argument (mentioned in an earlier email in the OP thread) is pretty reasonable to raise. The maintainers seems to be fairly on top of things though, acking and nacking as patches come in but this will take a while to process. I suspect very much that these commits will have to be rewritten to include subsystem labels and more accurate summaries by the maintainers if they want to include them. The patch set as an aggregate whole is garbage.
[0] https://www.offensive-security.com/metasploit-unleashed/msfv...
Plasmons are kind of cool because they can associate with photons to create polaritons. It's not clear to me without having read the paper if they're proposing that polaritons be induced or if the emissions are being caused by spontaneous plasmons in the graphene.
Well done to the people at MSR behind this paper!
[0] http://money.cnn.com/2015/06/26/technology/microsoft-windows...
The reason the language is all centered around Linux is because what they chose to do was do a Linux syscall compatibility layer. Really it could be called GNU/sLinux/kWindows but nobody is ever going to bother with that mouthful.
Edit: I should add that this doesn't mean I agree with the use of Linux here - I just understand why that's the case. I would much prefer if those involved went to the trouble of explaining what GNU is to those consumers who are interested. Pretty unlikely Microsoft would be leading that given GNU's position on Windows.
I don't think that you'd need a separate table for star bound listeners if the IP is mixed in since you could just hash in 0.0.0.0 but you'd need to check both the real IP and the special value too which is a potentially damaging performance hit. It's probably done with just the destination port for a good reason.
A naïve solution would be to choose a bucket based on the destination port as well as the source port if one is available (e.g. TCP). This might help balance load affecting particular local ports since we can assume the source port for TCP will be random enough. However, it doesn't solve the problem - it'll just hide it. Random spikes in latency for connections to random customers? Sounds undesirable.
A reasonable solution might be to work out a way to map gateway 53/UDP to a diverse set of ports which are bound to rrdns processes on the boxes which currently have 16K IP addresses. For UDP packets, this would be possible by doing on-wire modifications to the transport header and recalculating any checksums. Perhaps that just shifts the burden though.
It's not a recruitment operation. They're just some fun puzzles which are accessible to laypeople. It shows the fundamentals of cryptanalysis in a way that a casual reader can understand and even have a crack at solving.
Someone mentioned in another comment that Simon Singh's "The Code Book" starts in a similar way and they're dead on. You don't introduce someone to a subject by posing problems based on constructs they don't yet have the tools or context understand. The history of the field informs its current state - cryptography and cryptanalysis have a very rich and fascinating history.
Otherwise, an interesting project. I'd be interested to know why you chose Python and if/how you protect against code poisoning on the user's machine.
There is a middle ground and where it lies is directly related to the assessed risk. To support a mechanism is a binary choice but its design is not.
In the San Bernardino example, an unexpected potential adversary (Apple) has emerged. An unexpected vector is being discussed which has nothing to do with the encryption mechanism itself. Perfect cryptography doesn't imply a perfect cryptosystem and it sure doesn't imply perfect privacy.
The balance that needs to be found is around the assistance which is rendered to warranted agencies to enable their access to data. IMO vendor supported key material attacks are not an unreasonable solution but obviously that mechanism can go horribly wrong if the software is leaked and it is not adequately designed. The same can be said for signed updates in general though. This is a hard technical problem but it's not a binary choice where the agency has some magic key they can use wherever they want or they have nothing. If they can be enabled on a case by case basis such that it is cost effective for them to do the rest, that might be enough.
Obviously this is all based on the assumption of a robust local judicial process. However, whatever decision making process occurs needs to take into account global implications. Other commenters here and elsewhere have mentioned what this could mean for agencies in other countries where judicial process may be less robust. Many have commented about a lack of transparency in our own. This is a separate but very closely related concern. There are also considerations for the open source community and how precedent like this might be applied to them. It's a hard problem but it's not binary.
"And we agree on that, because we recognize that just like all of our other rights ... that there are going to be some constraints we impose so we are safe, secure and can live in a civilized society."
I'm not suggesting that this means POTUS and the government have the right answers at the moment. Despite that, we can't ignore the important role law enforcement plays in society, the requirements in support of their role, and the complexities surrounding the right to privacy. We need people advocating for the right balance, not just getting each other frustrated.
OP may have worries other than US law enforcement being from another country. This is one of the /many/ complexities in this space.
Previous thread on the phone before the release event:
That may or may not be what you were after since the book is probably more detailed at to the point than the course notes would be.
I picked up an old copy of the textbook and never read it. Maybe this is the kick I needed to pick up the newer edition and actually check it out in earnest!