2013-11-04 Mashable: Bitcoin Researchers: You Can Game the System

[Arvicco]

http://mashable.com/2013/11/04/bitcoin-cornell-researchers/

Seems like the researchers "discovered" a 51% attack. Wow, what a find - someone, please call the Nobel committee asap!

EDIT: The strategy described is subtly different from a 51% attack, more detailed discussion here: http://bitcoinmagazine.com/7953/selfish-mining-a-25-attack-against-the-bitcoin-network/

[chriswilmer]

I think this is referring to something slightly different than a 51% attack.

[Stephen Gornick]

http://mashable.com/2013/11/04/bitcoin-cornell-researchers/

The researchers "discovered" a 51% attack. Wow, what a find - someone, please call the Nobel committee asap!

Further discussion:

Majority is not Enough: Bitcoin Mining is Vulnerable
 - http://bitcointalk.org/index.php?topic=324413.0

[Bitcoin-development] Auto-generated miner backbone
 - http://sourceforge.net/mailarchive/message.php?msg_id=31597291

The Twitter accounts for the two researchers:
 - http://twitter.com/ittayeyal
 - http://twitter.com/el33th4xor

[cloudswrest]

It's not a 51% attack, but you do need a sizable fraction of the hash rate in order to be successful.  According to the algorithm the longest block chain wins.

1.    Find a successful hash but do not publish it.

2.    Start working on the next block.  While your pool is working on the next block, everybody else is still wasting time working on the previous block.

3.     Find the next hash and publish.  Even if your second hash comes after someone else finds another hash to the previous block, your block chain is a block longer than theirs.  You win.

It's basically doubling down.

[TraderTimm]

Where this "attack" fails is the variance in finding blocks. All it takes is one pool or individual to strike it "lucky" and find N+1 blocks faster, broadcasting the results. Then you're back at zero.

This isn't a flaw, it isn't a problem - but of course every muppet news outlet will run with big headline banners about "BITCOIN HAS A FLAW, CHECK IT OUT", since they loathe us so much.

Typical idiocy.

[cloudswrest]

It's not a "fail" it's an algorithm which, averaged over time, boosts your odds greater than your share of the hash rate.  Of course, if other people are doing it too it could lead to a lot of block chain instability leading to a longer settling time.

-B