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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 priv

by cs702 13y ago

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 private block chain that is temporarily longer than the public one, frequently enough 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. 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. 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. -- [1] https://news.ycombinator.com/item?id=6669735 https://news.ycombinator.com/item?id=6669735 [2] https://bitcointalk.org/index.php?topic=324413.msg3476697#msg3476697 https://bitcointalk.org/index.php?topic=324413.msg3476697#ms... -- Edits: moved paragraphs around and added sentence about and footnotes pointing to nullc's thoughts.

toomuchtodo 13y ago
"Blockchain Mutiny"
zwass 13y ago
> For example, what if other miners, instead of joining the selfish pool, decide to create their own competing selfish pools? I think the authors demonstrate why this would not be a preferable strategy: "above a certain threshold size, the revenue of a selfish pool rises superlinearly with pool size above its revenue with the honest strategy." So why create a new selfish pool when you could benefit more from joining the largest existing?
maxander 13y ago
While it does seem like this would give pre-existing selfish pools a competitive advantage (in addition to making the whole Bitcoin network less efficient), if you suppose that the selfish pool allows newcomers to join then it itself gains a sizable vulnerability- namely, that its advantaged position relies upon a secret (its extended block chain) that it must share with any potential collaborators. An actor concerned with the viability of Bitcoin, in this scenario, would simply join the selfish pool and turn double-agent, broadcasting the selfish block chain. Assembling enough human Bitcoin operators to dominate the present-day Bitcoin network that way, and keeping such a rowdy band of idealists in line, sounds implausible.
- dlitz 13y ago
  I don't think that would work. Bitcoin miners only need a small header (the root of a hash tree, essentially) in order to mine, but you need the full contents of the block in order for it to be broadcast into the honest network.

by cs702 13y ago

toomuchtodo 13y ago

"Blockchain Mutiny"

zwass 13y ago

> For example, what if other miners, instead of joining the selfish pool, decide to create their own competing selfish pools? I think the authors demonstrate why this would not be a preferable strategy: "above a certain threshold size, the revenue of a selfish pool rises superlinearly with pool size above its revenue with the honest strategy." So why create a new selfish pool when you could benefit more from joining the largest existing?

maxander 13y ago

While it does seem like this would give pre-existing selfish pools a competitive advantage (in addition to making the whole Bitcoin network less efficient), if you suppose that the selfish pool allows newcomers to join then it itself gains a sizable vulnerability- namely, that its advantaged position relies upon a secret (its extended block chain) that it must share with any potential collaborators. An actor concerned with the viability of Bitcoin, in this scenario, would simply join the selfish pool and turn double-agent, broadcasting the selfish block chain. Assembling enough human Bitcoin operators to dominate the present-day Bitcoin network that way, and keeping such a rowdy band of idealists in line, sounds implausible.

dlitz 13y ago
I don't think that would work. Bitcoin miners only need a small header (the root of a hash tree, essentially) in order to mine, but you need the full contents of the block in order for it to be broadcast into the honest network.