On Fri, Sep 15, 2017 at 10:14 AM, Adam Back via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > True however in principle a soft-fork can also be soft-forked out. Eg say > a publicly known soft-fork done by miners only that user node software did > not upgrade for first by opt-in adoption. > It depends on what software that the general user-base is using (especially exchanges). If a majority of miners have deployed a hidden soft fork, then the soft fork will only last as long as they can maintain their majority. If they drop below 50%, then the majority of miners will eventually make and then build on a block that is invalid according to their hidden soft fork rules. If the userbase doesn't support a censorship soft fork, then it will only last as long as a majority of miners support it. Once the cartel loses its majority, there is a strong incentive for members to disable their soft fork rule. Any that don't will end up mining a lower POW, but valid, chain. Users updating their nodes to enforce the soft fork is what makes the soft fork irreversible (without a hard fork). > A censorship soft-fork is harder, that's a standard hard-fork to bypass > with current fungibility mechanisms. > It's only a hard fork to reverse if the community is enforcing the soft fork. Forking off a minority of miners doesn't make it a hard fork. > > Adam > > On Sep 15, 2017 08:12, "ZmnSCPxj via bitcoin-dev" linuxfoundation.org> wrote: > >> Good morning Dan, >> >> My understanding is that it is impossible for soft forks to be prevented. >> >> 1. Anyone-can-spend >> >> There are a very large number of anyone-can-spend scripts, and it would >> be very impractical to ban them all. >> >> For example, the below output script is anyone-can-spend >> >> OP_TRUE >> >> So is the below: >> >> OP_SIZE OP_EQUAL >> >> Or: >> >> OP_1ADD OP_EQUAL >> >> Or: >> >> OP_BOOLAND >> >> Or: >> >> OP_BOOLOR >> >> And so on. >> >> So no, it is not practically possible to ban anyone-can-spend outputs, as >> there are too many potential scriptPubKey that anyone can spend. >> >> It is even possible to have an output that requires a proof-of-work, like >> so: >> >> OP_HASH256 OP_LESSTHAN >> >> All the above outputs are disallowed from propagation by IsStandard, but >> a miner can put them validly in a block, and IsStandard is not consensus >> code and can be modified. >> >> 2. Soft fork = restrict >> >> It is possible (although unlikely) for a majority of miners to run soft >> forking code which the rest of us are not privy to. >> >> For example, for all we know, miners are already blacklisting spends on >> Satoshi's coins. We would not be able to detect this at all, since no >> transaction that spends Satoshi's coins have been broadcast, ever. It is >> thus indistinguishable from a world where Satoshi lost his private keys. >> Of course, the world where Satoshi never spent his coins and miners are >> blacklisting Satoshi's coins, is more complex than the world where Satoshi >> never spent his coins, so it is more likely that miners are not >> blacklisting. >> >> But the principle is there. We may already be in a softfork whose rules >> we do not know, and it just so happens that all our transactions today do >> not violate those rules. It is impossible for us to know this, but it is >> very unlikely. >> >> Soft forks apply further restrictions on Bitcoin. Hard forks do not. >> Thus, if everyone else is entering a soft fork and we are oblivious, we do >> not even know about it. Whereas, if everyone else is entering a hard fork, >> we will immediately see (and reject) invalid transactions and blocks. >> >> Thus the only way to prevent soft fork is to hard fork against the new >> soft fork, like Bcash did. >> >> Regards, >> ZmnSCPxj >> >> -------- Original Message -------- >> Subject: [bitcoin-dev] hypothetical: Could soft-forks be prevented? >> Local Time: September 13, 2017 5:50 PM >> UTC Time: September 13, 2017 9:50 AM >> From: bitcoin-dev@lists.linuxfoundation.org >> To: Bitcoin Protocol Discussion >> >> Hi, I am interested in the possibility of a cryptocurrency software >> (future bitcoin or a future altcoin) that strives to have immutable >> consensus rules. >> >> The goal of such a cryptocurrency would not be to have the latest and >> greatest tech, but rather to be a long-term store of value and to offer >> investors great certainty and predictability... something that markets >> tend to like. And of course, zero consensus rule changes also means >> less chance of new bugs and attack surface remains the same, which is >> good for security. >> >> Of course, hard-forks are always possible. But that is a clear split >> and something that people must opt into. Each party has to make a >> choice, and inertia is on the side of the status quo. Whereas >> soft-forks sort of drag people along with them, even those who oppose >> the changes and never upgrade. In my view, that is problematic, >> especially for a coin with permanent consensus rule immutability as a >> goal/ethic. >> >> As I understand it, bitcoin soft-forks always rely on anyone-can-spend >> transactions. If those were removed, would it effectively prevent >> soft-forks, or are there other possible mechanisms? How important are >> any-one-can spend tx for other uses? >> >> More generally, do you think it is possible to programmatically >> avoid/ban soft-forks, and if so, how would you go about it? >> >> >> >> >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > >