The old chain Ethernet parallel world workshop

The old chain Ethernet parallel world workshop

Although the etheric Fang through hard to solve the problem of TheDAO bifurcation of the stolen funds, side effects is the etheric Fang split into ETH and ETC in a parallel world, triggered a dual currency to sell, replay attack phenomenon. Analysis of the principle and Prospect of the future of double chain. The TheDAO incident, see: “or” Trilogy Mourning, “DAO” and “pilfer end coin” zhao.

The etheric double stranded life square

It was said that the etheric Fang community through hard bifurcation (hardfork) technology, “back” the hacker control of TheDAO funds, TheDAO refund after it come to an end. What was supposed to be silent, but had not expected, after the wash basin has a hole, the final blow to the hacker is fantastic to be abruptly split into two square Ethernet parallel world!

The house, the parallel world (ParallelUniverses) are not a strange concept in Physics: it is separated from the one in the world, with the original parallel world exists both similar and another world is different, the same thing has a completely different results in the two world.

The use of words hard branch technology, by modifying the etheric Fang software code, in the 1920000th block of all funds forced the TheDAO and DAO (including hacker control part) all go to a specific contract refund. This contract is the only to raise the public. According to the 100:1 DAO currency exchange for the original Ethernet coin.

This is a hard time before and after the bifurcation in block 1920000th, the left figure for block number, right 16 hexadecimal number represents block hash values. After the bifurcation lines represent new chain, most of the miners have to upgrade software and accounting in the chain (mining); the branches represent the original curve (old) chain, few upgrade miners still stay in the old chain accounting. A new chain speed is greater than the old chain, most stress have switched to the new chain.

In the hard bifurcation block chain, because of changes to the system of rules, in accordance with the new rules generated by new node block only recognized, old nodes do not think the new block legitimate. Therefore, the old node has been the old rules to organize their chain, so no matter how old the proportion of the number of nodes, will produce two chains. If a majority of nodes are upgrading to a new version of the old chain, survival depends on how much power support.

Before bitcoin blockchain also appears on the excellent bifurcation of the situation, the vast majority of miners are switching to a new chain, the old chain will automatically disappear. The etheric Fang hard is different because of the existence of bifurcation, differences in community, some miners also continue to maintain the old chain, so the old chain did not immediately disappear, still alive. From the economic point of view, the miners in the old chain dug out of the “old” in the etheric coins almost no value, not only in the exchange can not deal, but also because the old chain of dead or alive, no one is willing to bear the risk of buying old coins. The miners had no income, the old chain. It is only a matter of time.

Precarious in the old chain as Savior appeared. Poloniex is the world’s largest trading platform Ethernet Fang (P) first announced the start of the old version of the etheric currency trading. The new version of ETH and Ethernet for currency differences, old code named ETC (EthereumClassic, classical aether square). ETC has the value of circulation, because the price is very low, is willing to take the risk of investment (machine) to buy the miners to continue living. The old chain is much smaller than the new chain, difficulty and cost than the new chain is low, some swing miners (pool) see profitable, have joined the old mining chain, the whole network is rapidly increasing, and the new chain is from 1:20 soared to 1:4. In addition to P, other ETC originally opposed to trading platform, online wallet service see demand, also changed his mind and began to support ETC, and even Github in the branch a few days ago also appeared in the EthereumClassic project. The old chain back to life! In contrary to expectation, and in reason!

The price fluctuations of ETC

Replay attack (ReplayAttack)

At the same time there are two new Ethernet square chain (ETH and ETC), the same code (in addition to involving the TheDAO part), history books (as before, the private key bifurcation) address is the same, is broadcast to two online transactions are legitimate, many unbelievable thing happened. For example, hold etheric coins before the bifurcation (ETH) users, in the post bifurcation also have the same amount of ETH ETC coins and coin. That is to say that if you have 1 ETH money, after bifurcation suddenly nothing out of the 1 ETC money, and can sell flowers in the old chain, as a kind of money to fall from the sky.

In addition to more money into a “wonderful”, also brought a replay attack (ReplayAttack). For example, in the new chain of sending money transactions, will also be broadcast to the old chain, and the transaction can succeed (behind that exception), can be utilized as a means of attack.

If before the bifurcation of 100 ETH A address, B address has 500 ETH. After the bifurcation in the ETH chain, from A to 100 ETH address to B address, and then the 100 ETH from B A A to address, eventually have 100 ETH (net loss of a small amount of gas, B address) balance constant. The transaction in ETC chain also broadcast a (replay), also from A to 100 ETC to B, from B to 100 ETC to A, everything is normal. However, if the attacker managed to make the A balance in ETH in the chain of 100 ETH, in the ETC chain amounted to 0, the transaction in the ETC chain reproduction, B from A failed because of lack of balance; balance for B enough, from B to A successfully, the result is that A took away from B 100 ETC.

This is the most typical replay attack target currency exchange Ethernet, the attacker from his address to the A address of B exchange coin and then initiate the currency exchange request in the ETH chain to confirm the transaction and put money to A, but also do not know the transactions executed in the ETC chain, the ETC exchange had been withdrawn. Why is the exchange? Because the exchange address B general store multiple clients ETC coin, balance is large, so easy to attack. Part of the exchange because of lack of preparedness caught, some also have to pay to the customer ETC.

Replay attack is also a prerequisite, is the need to have a balance of two A in the address in the chain, this is how to do it? The easiest is to think of TheDAO chips, they can get their investment TheDAO ETH currency in hard after the bifurcation in the ETH chain, but the ETH in the corresponding ETC chain is still stored in the TheDAO contract, because of the bifurcation, ETC and ETH is the difference between the amount of the contract in more than TheDAO the following figure. People get their TheDAO chips ETH, have such a different address: balance in the old chain. The back will introduce another method of staggered address in the old and new balance chain.

The etheric Fang hard moment old chain block difference bifurcation

Distinguish between old and new currency chain ether

Two block chain ETH and ETC homology coexist, exchange each other, bring the confusion suddenly, do business in any chain, to take on a chain on whether there is a replay effect. The best way is to put in the ETH and ETC stored in a different address, which do not affect each other. The official recommended intelligent Ethernet square contract third party, you can put the original with the address of the ETH and ETC to the new address is different, which is originally in the double chain are stored in X Ethernet address to ETH address currency, respectively Y and ETC Z. The following is a safe partition contract code, in the split () in which the contract operation chain judgment method, and then put the ETH/ETC to the target address on different. This code is a bit like the operating system process fork call, determine the code in the end in the parent process or operation. Code used in another called Oracle (the Prophet) the contract AmIOnTheFork, the address is 0x2bd2326c993dfaef84f696526064ff22eba5b362. This contract is issued to the block chain in hard and hard in the bifurcation, bifurcation, according to the balance of TheDAO hacker contract, immediately record contract is in new or old chain chain, which provides a theoretical basis for other contracts. Because of the limited space, not including its principle, interested readers can view the source code of the Oracle contract:


Split contract source code

The old chain dispute

Although the long-term trend is not clear, at least short-term ETC has survived. The ETC value rose from 2 yuan to a maximum of 18 yuan (RMB), and accompanied by a huge amount of turnover, and even some people also estimated ETC in the future prices will be higher than ETH. So who is behind the ETC? A guess is bitcoin circle of people. Bitcoin is the boss in the money fully deserve encryption, certainly do not want to have a younger brother to become more and more powerful, and eventually become their opponents. Now, the rapid growth of the younger brother of the etheric Fang, there have been signs of beyond bitcoin, bitcoins can sit idly by? The bitcoin community on the etheric Fang hard bifurcation are condemned basically, there is now a ETC of this rare opportunity, bitcoin bigwigs couldn’t help eating cheap ETC chips (a large number of ETC with BTC was bought), with little cost, can control a confrontation and ETH chain this is a great opportunity for the car.

On the other hand, a large block and block between the two parties have been bitcoin community, large blocks of the bitcoin network can solve the problem of low throughput, but rely on hard bifurcation to achieve, this was strongly opposed to small pieces of pie. The bifurcation of the etheric Fang hard success, are of great significance to the whole block chain bitcoin community, small piece of pie certainly hope that ETC can survive, thus proving hard bifurcation with great risk, small piece of pie ETC should be the most loyal supporters. Exchanges are basically engaged in bitcoin started, influenced by various bitcoin forces, support ETC of the transactions be not at all surprising.

The emergence of ETC, the focus of the debate from the etheric square community TheDAO transferred to ETC and ETH’s future development. One view is that, compared to ETC and ETH, to the center of the system is more pure, it will win in the end. Another view is that ETH supported by the majority of people, as well as the core developers Vitalik support, ETH is representing the future. So, who is the master of public block chain system and judge?

The author believes that the etheric Fang (ETH) has abundant capital, excellent development team, technical route clear, ecological circle of many users and partners to form a huge, it has the advantage of long-term development. The classic etheric Fang (ETC) to catch up from behind, it is essential to have a core technical team of independent innovation. Now ETC and ETH are two items in the same source code, ETC and ETH are compatible. But if the long-term dependence and ETC follow ETH’s technical route, do not have their own team and development blueprint (similar to Ethernet from Frontier to Serenity square planning, even stir even ETC) its value is higher than ETH, the short-term to attract popularity, can finally win the trust of the users.

The ETC chain is 620GH/s from the peak from the 900GH/s down to the block height above, behind ETH2000, difficulty is also less than ETH


From the beginning to the TheDAO launched to raise the public, the stolen money to debate the soft and hard bifurcated, to double stranded Ethernet square coexist, experienced all forces were groundless talk, intense game in technology, economy, morality, ethics and other aspects, has a history of drama. I believe that many technology enthusiasts are like author, see many block chain novelty, such as DAO code control mode, all double stranded parallel world interaction etc.. The TheDAO series of articles and everyone to do the analysis and share, there is more progress in the future, will continue to communicate with you.

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