On Tue, Nov 05, 2013 at 11:56:53AM -0500, Ittay wrote: > Hello, > > Please see below our BIP for raising the selfish mining threshold. > Looking forward to your comments.
<snip> > 2. No new vulnerabilities introduced: > Currently the choice among equal-length chains is done arbitrarily, > depending on network topology. This arbitrariness is a source of > vulnerability. We replace it with explicit randomness, which is at the > control of the protocol. The change does not introduce executions that were > not possible with the old protocol. Credit goes to Gregory Maxwell for pointing this out, but the random choice solution does in fact introduce a vulnerability in that it creates incentives for pools over a certain size to withhold blocks rather than immediately broadcasting all blocks found. The problem is that when the pool eventually choses to reveal the block they mined, 50% of the hashing power switches, thus splitting the network. Like the original attack this can be to their benefit. For pools over a certain size this strategy is profitable even without investing in a low-latency network; Maxwell or someone else can chime in with the details for deriving that threshold. I won't get a chance to for a few hours, but someone should do the analysis on a deterministic switching scheme. -- 'peter'[:-1]@petertodd.org 0000000000000005e25ca9b9fe62bdd6e8a2b4527ad61753dd2113c268bec707
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