Bitcoin Forum

https://bitcointalk.org/index.php?topic=113654.0

A test of the 51% attack post GPU age?

It's very interesting. It's a legitimate organization with no hostile intent though. Bitcoin can only benefit from something like this in the long term.

I guess you are right, but who knows?

Also, I think if they actually would achieve 51% of hashing power, that would startle alot of people and a flash crash would follow. Probably with quick recovery but still a heavy spike. Other than that I see little effect on price.

really doesn't sound like a 51% attack; more like an exploit in timing btwn block formation.

I'm interested in the hardware they are running to just magically have ~10% of the network lol

No.
Please go read their paper. What they are doing is more than just proving an attack vector. It is to prove a possible shortcoming for the security of fast transaction processing and to offer a possible solution for any issues they can prove with it.

They mis-speak imho when they state they are to prove 'it can be done cheaply', as it would undoubtly cost several millions of dollars for the ~10% of network total hashing power they are utilizing to prove their attack vector. This would be a greatly pohibitive cost for an entity looking to take advantage of a transaction that would likely be for less than $20 in the situations they are seeking to show would rely on fast transactions. None the less, their approach is thorough and their solutions are likely to be quite beneficial to future businesses and transactions carried out in BTC. I'm thinking more along the lines of banks or other entities who have a need to process large volumes of small transactions and to do so quickly.

cheers

I think this is great news.

Actually, the setup they propose to perform the double spending attack during 0-confirmation payment is very cheap. You only need a number of machines running standard Bitcoin clients and one attack machine with modified Bitcoin client.

hey, you changed it!  that's ok.  thanks for keeping it up so long.  you're a good sport.  :D

What's the new avatar proudhon? Does that somehow symbolize the bitcoin foundation?

My guess is they are somehow trying to exploit the variance in confirmation time by varying the network mining power.

No.  It's this (http://www.talkingalpacas.com/).

Is it your project? I look forward to some depressing doomsday talk! ;)

Yes, it is my project.  Had to put it on hold for a while, but I'm picking it up again.  I spur of the moment sort of thought that letting the cat out of the bag would put a fire under my feet to get some content out the door.  The fact of the matter is a pretty large proportion of what I post here is posted as a sort of parody of a lot of the sort of talk that goes on around here and, in weird way, a parody of a lot of my thinking and posting last year.  Embarrassing as it is to admit that, it is what it is and it's something I'd like to start moving away from (though, it's just so temping sometimes).  

This is a round about way of getting to the point that I intend to avoid depressing doomsday talk.  In fact, I'm intent to make market talk and price talk a very, very small part of the podcast, if it features at all.  Rather, my aim is provide discussion of relevant current events and, more prominently, I'd like the podcast to focus on stories.  Specifically, stories from and about notable people involved with bitcoin and stories and discussion about interesting events that have happened in this little universe since 2009.  I hope to offer something informative, entertaining, and well produced; so, yeah, you're going to see a side of me that's more serious and less absurd than my posting history.  I'm even thinking of moving off of Proudhon and to my IRL name...

Wow, sounds really interesting  ;D

I look forward to it! Incidentally Im working on something similar, soon to be announced, maybe I can draw some inspiration from you  ::)

Holy Cow.  we'll actually get to hear your voice.  throw a few bull snorts in there would you?  ;)

FUCK
This is bad. Real bad.  :o

Why? 5 blocks in a row and appearing fully legit.

False alarm. See the last post in that thread.

puh.. thanks.

still this raises the question how they got around to relaying this many blocks. By chance alone that means they are up to something.

link to what your talking about?

well no link but how it looks it's like they have a _very_ good connection to the bitcoin network. By network latency alone that is unlikely that they relay that much in that amount of time, there are probably some way to archive this result if you have multiple hosts, and some good connection on everyone. But I can't explain what exactly.

My guess is they are establishing a huge degree of connectivity (likely connecting to every node) and only passing out the nodes they control when outside nodes ask for peers.  They are the first to be notified of the blocks and then broadcast them out to every other node.

As a side note, they could also attack a particular node by sending a transaction to them and simultaneously sending a double spend transaction to everyone else.  That's likely what they are referring to in the article.

As for their solution, I couldn't find any info, but I'll think about it.

the guy who did it said in his thread, that he actually only "relayed" those blocks from some of his 5000! connected nodes but didnt actually mine any.