Exactly.  I don't know why one calls that a "replay attack".  If the signature is out, the transaction is executed, and as the signature is valid on both chains, the transaction is of course executed on both chains.

Naive people who think that if they only send that signature out on one network, do the transaction on one network, forget that this signature will be *published in a public block chain* and will hence also be swooped by a miner of the other chain to get the fee.  But that's not an "attack", you PUBLISHED the signature.

The trick is to mix into every transaction that you only want to do on one chain, an UTXO that is only valid on one chain. Then the signature will not be accepted on the other chain.  Recently mined coins can do, or of course, the DAO coins.  But you need to get some, first !

Of course not.  It is a split.  A fork.  Every old coin is now both the new coins, and its value is the sum of the values of the new coins.  Ideally, the market cap splits too (but given the volatility, and the event itself, that's difficult to observe).

new-ETH is roughly about 90% of a pre-fork ETH and ETC is roughly about 10% of the pre-fork ETH at this moment, give or take it 5-10%.  That's true in market value, and in hash rate.

An old ETH is hence for about 90% a new ETH, and for about 10% an ETC.


Of course, but the pre-fork ETH is not the same as the post-fork ETH.  The pre-fork ETH was 90% post-fork ETH and 10% post-fork ETC.

Forking is not the creation of a new currency, it is splitting the old currency in two parts (which have different market valuations, but whose sum market valuation is more or less the continuity of the former market valuation of the pre-fork coin).

You can compare this best with something like shares in a company.  If you have shares in company XYZ, and then this company splits in two, namely new company X-new, and new company YZ-new, then your former shares are now shares of both companies.  So if you borrowed someone shares XYZ before the split, then they owe you BOTH shares in X and in YZ after the split.

The rationality of markets is often unfathomable.  But there's nothing inherently mysterious about it.  Monetary assets are infinitely recursive belief systems, and anything can happen in such systems.   It is a fairy tale of economy books that money has some "commodity" value, or some "debt promise" value.  Money is something you accept because you believe that someone believes that someone believes that someone .... will accept it.  So as long as you believe that someone believes that someone will accept a DAO token against value, you also accept it against value (especially if you think that some may believe that some may believe that it may be accepted against more value - which is the greater fool theory).

So anything goes, essentially, in the trading of monetary coins, because of this infinite belief recursion.

The whole bicycle was the pre-fork ETH.  Now only front wheels exist (ETC) and bicycle frames without a front wheel (post-fork ETH).

What line of code for ETH will not be also a line of code for ETC (apart from the few if statements concerning the DAO of course...) ?

The point is that the pre-fork ETH is AS WELL the new ETH as ETC.     If after the fork, you agree that they only have to return ETH, why don't they return only ETC then ?  (that's even closer to the original chain).

Normally, during a fork, the market cap also splits over the daughter coins.  If you were doing things on-chain, then the lending was a pre-fork signature for pre-fork eth, and the returning should have been a post-fork signature of exactly those same coins, which would give you a valid transaction both on the ETC and on the ETH chain (because they originated from a signature of a pre-fork coin, which is of course valid on both chains too).

If I lend you a bicycle, then you shouldn't return just the front wheel or the rest, but both.

ETH after the fork is only part of ETH before the fork.

But what is this thing with a "replay attack" ?  To me that's no attack at all.  If you sign a transaction that was on the old chain, then of course that signature is as valid on the new chain A as on the new chain B.  Remember that what was protecting your old UTXO on the old chain was the fact that you didn't gave out a valid signature and that you were the only one being able to produce one.  So once your signature is out, it is of course out for both chains.

The trick is to only sign transactions that include UTXO that are only valid on one chain.  For that, you need to obtain 1) DAO hacker coins or 2) DAO return address coins or 3) freshly mined coins on one of the chains.  You don't need much of it: a bit of dust of one of these is enough to make a transaction that will be considered invalid on the other chain, so that you can REDO a signature, but this time on the second chain.

But for sure it is not an "attack".  I don't know why people call it that way.  If you have given out the signature in public, of course people will use it.

I agree with the OP, but on the other hand, the demand for "the world computer" is essentially over.  The true platform for that is closer to ETC than to the ETH spreadsheet as you say, but I think that none of it is in demand.  Or maybe tiny contracts to lend out a bike :-)

On top of that, when ETC reaches $3, you will be able to buy 10 times more ETH with it :-)

I can go with the idea that it *became* a scam at a certain point, when the over-ambitious authors of it realized that this thing grew totally over their heads and didn't know how to get out of it.  But I do think they were honest at the beginning at least, with truckloads of hubris and ego-inflation.

I don't think that it was an intended scam from the beginning, but more something akin of this:

https://www.youtube.com/watch?v=K1kuy2yIRdc

I answered that.  He's not a thief according to the "code is law" system.  He might very well be considered a thief under "human paper contract law".  As the "code is law" system has been broken by the fork, the legal system in which he did his legal things has retro-actively changed from the law into something akin of the "decision of the King" (or of the mob).  As this whole circus of "the code is the law" is in ANY CASE probably not valid from a human law point of view, there's no point for him to go to court.  So why did he say something that wouldn't make sense in a human court (and he must have known that) ?

I have a theory of why he might have issued these legal threats even though he probably didn't have a foot to stand on in the human law frame: his goal was not to become rich, his goal was to break ethereum.  Now, by threatening with legal action, he made it much more probable that the OTHER SIDE (the DAO bagholders) would also threaten with legal action if nothing was done, and hence use them to scare the hell out of the ETH foundation, so that they would break their system with a fork or something.  As such, what should have been a DAO-limited disaster has affected ethereum itself, so that these guys showed that not only their coding language was tricky to use, but moreover that their whole block chain was rewindable, so that in the end, NOTHING remained of the ethereum proposition: a buggy star application, the DAO, a tricky programming language, and on top of that, a broken block chain and a broken promise of unstoppable contract.

In other words, his threat of going to court was nothing else but a bait to stimulate a fork and screw up the whole system.  One cannot say that he failed, but in any case, it was a win-win situation: by doing so, if the ETH foundation would have stood firm on its principles, he could have cashed out severely, or he would have lost his stash, but the ETH foundation would have screwed the last bit of credibility in their principles, which was his announced goal.

ETH (before the fork) was bubbling because of the promise of complex smart contracts.  People thought that in the long run, ETH would become the basis for a lot of business contracts which is a HUGE value.  But that's totally, finally, completely over now.  No-one in his right mind is going to put millions again in a risky programming adventure that most probably will not behave as intended and will hence be hacked.

So what's there for ethereum left to do apart being a coin, and maybe a testbed for tiny contracts that could, with some effort, be implemented on top of bitcoin too ?

As a matter of principle, I also prefer largely ETC.  I'm not invested in it at all (I don't do crypto apart from hodling a few bitcoin from long ago, at most I buy some coins with pocket money to play with and to buy a thing over the internet).

But I think that both reached more or less their level.  ETH was on its way to become a bitcoin challenger, but the inevitable happened with the DAO, and that was a good thing, because ethereum is fundamentally flawed because of its too complex contract system which is Turing complete.

Maybe it will remain a playground for very small contracts.  ETC would in principle be better, but I guess that ETH can be used too as they won't fork over tiny contracts.  But essentially the dream is dead.  There's a lot of money in ETH now, so they keep it alive amongst themselves.  The split between ETC and ETH is consumed.  But I don't see why either of them would take off.  Rationally, one would think that the optimal spread of risk would bring the market caps of ETC and ETH together.  But markets do not always behave as one would rationally expect.

In any case, the hype of complex smart contracts, and the "code is the law" is probably cooled off now, and without that hype, ETH has no genuine reason to exist, apart from the whales that have already money in it, and must keep the price on level.

We must thank the DAO hacker for stopping this madness in time, before it did real damage.

Now for real, don't you think the ethereum story is essentially over ?  Of course eth will still exist a long time and most probably etc too.  But the concept has shown to fail as a platform for smart contracts: Turing completeness is too dangerous.  The thing can still exist as a coin without smart contracts, but what's the point, besides yet another crypto currency ?

So now we have a criminals' ether, ETC, and a cheaters' ether, ETH.

The only thing we don't have, is people running smart contracts on them :-)

This is somewhat unfair.  An anonymous payment service only has to be anonymous concerning the payment, not concerning the counter service of course, with which it has nothing to do.  Of course, if I want to buy a physical good, I have to provide for some delivery information to the person I'm buying the good from, that's unavoidable.  But that has nothing to do with the payment.

But consider, for instance, that I want to be an anonymous funder of, say, the Islamitic State.  I only want to do an anonymous transaction of value so that nobody can find out that I was the one who has donated value.  Then there's a serious chance that something like Monero can help, while it would be utmost dangerous to do so with Bitcoin.

I would first buy bitcoin on an exchange.  This would be traceable.  Then I would transfer those bitcoins to an exchange that has monero on the list.  That would be traceable too.  Then I would convert my bitcoins to monero.  The exchange would know that.  I would then withdraw my monero.  That's also traceable.  There's no need to try to hide that, it won't work.

But then I would do several Monero-monero transactions between addresses of my own.  If I had a monero node running for a long time, I could do that directly on my monero node for some transactions, and I could use Tor for other transactions.

At this point, I can assume that the trace of the value to me is essentially whiped out.

Next, the most critical step would be to go to a public place, connect to a public net, and, through Tor, using something like TAILS, give the final order to transfer my donation to a monero account of the Islamic State in my example.

I think that that value transfer is essentially unlinkable to me.  In as far as it is, I would say that Monero succeeded in providing true anonymous transfer of value.

Just to make clear: I only use "Islamic state" as an extreme example of where you can think that the powers that be put all efforts to trace funding.  I'm not a funder of those criminals at all.

There's nothing "improved" by the ETH fork.  They only moved the DAO funds to a different address "deus ex machina" in order to bail out the failed project which had undergone unexpected transactions according to the code and with which many people disagreed with because it was against their profit.

That's funny, because ethereum classic is exactly the code and the chain that has been running since before the fork.  The only thing that was new was the modified code that goes now under the ETH name, but is in fact a modification of the original. 

Suppose that tomorrow, Satoshi makes himself known, and comes out with a modified version of bitcoin core.  Is the original chain from that point onward then a scam ?  Are people not updating to his new version scammers ?

In what way did they have an insecure smart contract ?  They simply had a smart contract that didn't do what they said/intended it to do.  But that's normal.  No code ever does exactly as intended.  They told you upfront that you shouldn't take their intentions as the law, but rather the code.  And then people came in and changed the block chain, so that what they said wasn't true either.  Now nor the code, nor their intentions are the law.