Majority is not Enough: Bitcoin Mining is Vulnerable
The authors argue that if a "selfish" mining pool of size above a certain threshold keeps newly discovered blocks secret, this pool will be able to build a <i>private</i> block chain that is <i>temporarily longer</i> than the public one, <i>frequently enough</i> to make the selfish strategy more profitable than the honest one (by revealing longer private chains just before the public one catches up), so in theory more and more rational miners will join the selfish pool, which will therefore quickly grow to control a majority of all nodes.<p>In theory. There are many complex and subtle issues that must be thoroughly analyzed before passing judgment on this paper. For example, what if other miners, instead of joining the selfish pool, decide to create their own competing selfish pools?  Also, as nullc points out elsewhere on this thread[1] and the Bitcoin Forum[2], peering between miners is already so extensive that temporarily keeping blocks secret could be much costlier than assumed by the authors of the paper.<p>The Bitcoin community must go through this paper in detail, but IF the authors' logic and math prove correct, this could be a real vulnerability.<p>--<p>[1] <a href="https://news.ycombinator.com/item?id=6669735" rel="nofollow">https://news.ycombinator.com/item?id=6669735</a><p>[2] <a href="https://bitcointalk.org/index.php?topic=324413.msg3476697#msg3476697" rel="nofollow">https://bitcointalk.org/index.php?topic=324413.msg3476697#ms...</a><p>--<p>Edits: moved paragraphs around and added sentence about and footnotes pointing to nullc's thoughts.