Can't he just publish the series of blocks containing the double spend and stop mining as the honest miners will start mining on top of his last block? And when he wants to attack again start mining only then.
A single double-spend by someone investing in a majority of the control of the coin doesn't make much economic sense.
Against Dash and Satoshi's design (e.g. Bitcoin) that can theoretically be executed with a much less costly Finney attack (where the attacker wins a block but doesn't announce it right away and first announces his double-spend, which is even more likely in Dash's InstantX because the confirmation is instant making it much more feasible to fool the unwary merchant who was assured that InstantX is instantly confirmed so not to wait for chain confirmations), so no need to invest such massive resources. And there are other less costly attacks specifically on Dash that monsterer alluded to and I will be following up on in future posts.
So our crypto threat model for taking total control of the chain isn't really a single double-spend but rather:
- Ongoing double-spend or other mischief (e.g. dropping transactions by orphaning chains) to crash the price of the coin. This applies more to an altcoin that hasn't graduated to widespread adoption.
- Having the longest chain meaning they can blacklist any block announcement or transaction they want to, or even change the protocol entirely in subtle ways that the masses won't object to. This applies to a coin that has widespread adoption and geopolitical-economics implications.
Personally I am most concerned about state regulated pools and miners being able to blacklist transactions that don't carry KYC identification number on them, as dictated by some future NWO (or G20 cooperation recently announced) authority that has the power to take control of more than 49% of the hash rate ongoing. That is why even the excessive ongoing cost of such is not sufficient of an argument to me of security, because the State profits from being able to maintain their power of taxation and other monopolistic powers for those fascist corporations that effectively control (leech on) the State. Personally I think it is assured that is where Bitcoin is headed over time, because it is the most natural outcome.
So although the asymptotic math implication is astute and aids the conceptualization of a model, that is why I am not fully satisfied only with monsterer's distinction being that the cost is sublinear versus constant for PoS. And I was never satisfied with the standard retort from Bitcoin supporters that the people will move away from any ubiquitous coin which is being so abused, because the fact is the masses don't care. Once a crypto coin becomes ubiquitous we are stuck with that technology because the masses won't change their electronic unit-of-account and unit-of-exchange again. As long as the masses don't feel they are inconvenienced or troubled, they won't rise up to kill off such an insidious 49% attack that only blacklists those who don't comply with KYC. Instead for Bitcoin (perhaps with Lightning Networks for microtransactions) everyone will comply with KYC, not be blacklisted, and there will be no problem except for excessive taxation and global top-down command economy collapsing into a Dark Age that chokes off the Knowledge Age. For example, we can look forward to the EU, Obama, Putin, and China dictating to us what sorts of businesses we can't create, the net neutrality means we all pay through our nose an internet tax, and that we can't use encryption, etc.. Basically if we don't have permissionless commerce then the State can destroy humanity. That is way socialism dies. I'd prefer a permissionless release value so that the Knowledge Age can flourish and humanity can be free to conduct commerce without oppression of the Corporate-State-Fascism-Technocracy that we are sliding into now.
Note I have become more convinced that for technical and inertia reasons, Bitcoin can't scale even with Lightning Networks (because LN requires block chain scaling also for the worst case garbage collection surges and more importantly because LN isn't an end-to-end principled solution so it isn't always available and opaque to the ends thus it can't scale to spontaneous payments between 100s of millions of users). That isn't a 100% given, just my appraisal at the moment which is subject to adaptation. Thus I worry less about that NWO outcome coming from Bitcoin and instead worry more about the failure of Bitcoin and the implications thereof. But I think it is impossible the free market of hackers won't rise up with a solution. And I am one of them who is trying.
So that is one of the main reasons I have invented this new design, in addition to addressing the block chain scaling issue and the 1 second microtransaction instant confirmations issue (which is necessary to serve the viral growth I am planning for my marketing strategy). It all fits together. But executing this is a major undertaking and challenge for one past-middle-age man in a room in the Philippines (who also happens to have some sort of strange inflammation illness that mimics autoimmune disease such as Multiple Sclerosis, neuropathy, or something akin to that).
Edit: I explained to monsterer upthread, how I claimed to have reduced the electricity for PoW chain to an insignificant amount, thus correcting another long-standing issue with Satoshi's design.
If these claims sound like magic, then great. I prefer it to stay that way until I have already something launched. I have already revealed enough information that someone very determined could prove that my design is legit and implement it on their own. But that someone would need to be quite skilled. I am not spelling it all out in a coherent single paper at this time, because I am trying to keep potential copycats blinded for now. I have carefully phrased these discussions so that someone of monsterer's caliber can hopefully get the gist of it. I think it is important to at least verify that he wasn't able to shoot it down immediately due to some simple flaw. He needs a more comprehensive description to fully develop his analysis though. I am under no obligation to reveal details now, because I haven't launched nor sold anything to this forum (nor to the public any where yet). I am revealing some details now.