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BCHA is suffering from continuous computing power attacks from suspected BCHN supporters, mainly in the form of empty block attacks. The offensive and defensive sides have carried out multiple stages of strategic adjustments.
Regardless of the outcome of the attack, the BCHA offensive and defensive battle provides us with a good example for understanding PoW and the problems in the development of decentralized cryptocurrency, which is worth studying and thinking.
1. The three forks of BCH
On November 15, 2020, BCH forks again. This is the third fork after the birth of BCH on August 1, 2017 and the fork of BSV on November 15, 2018.
The reason why BCH will fork is that the decentralized crypto economy will produce different exploration directions in the evolution, just like the evolution of biology. However, the more frequent BCH forks are due to the fact that the decentralized cryptocurrency has not yet formed an effective governance mechanism, and BCH has a higher degree of decentralization, the development team is diversified, and the opinion leaders are diversified. It is easier to split due to major differences. cross.
Other public chains either have their own strong ecological centers, such as most public chains such as ETH and TRX; or they have moved from decentralization to centralization, such as BTC forming the Core center and BSV centered on the CSW team; or simply no development community , There will be no forks, such as Dogecoin, LTC, etc.
The 2017 BCH fork from BTC was due to the expansion dispute (see https://www.8btc.com/article/450758), and the 2018 BSV fork was the failure of the CSW team’s organized seizure of power (see https://www.8btc) .com/article/287572), experienced protracted and fierce wars on both occasions, and hostilities and attacks have even continued to this day.
In contrast, the cause of BCH’s fork was somewhat unexpected, the war was relatively mild, and the impact was relatively small. However, the internal logic of the decentralized crypto-economy ecosystem was drilled and demonstrated during the fork, which is still very valuable.
2. Reasons for the fork of BCHA
This time, the BCHA fork occurred. The root cause is the lack of an effective decentralized governance mechanism. The direct reason is that the original core development team of BCH, ABC, regardless of community differences, used code management rights to arbitrarily transfer IFP (8% new currency per block) (Pay to the address controlled by ABC) The code is written into the upgrade node program, and an announcement will be made to upgrade on November 15.
The problem behind this is that BCH, which does not have a mature governance mechanism, has in fact formed the greater power of the ABC team, while ABC is not good at governance and politics, and after leading the development for 3 years, it has a arrogant mentality and is more The opinions of the authors, related companies and other influential members are no longer taken seriously, and there are even more complaints.
At the same time, after a three-year bear market, ABC’s funding pressure is relatively high, and the opportunity cost of focusing on BCH development and maintenance is high. Due to some complaints and frictions, the relationship between ABC and donors has also deteriorated and donated funds have decreased.
ABC originally had high support in the ecology. Opponents of the IFP have also been trying to resolve the crisis through communication and avoid division. Some supporters of IFP also advocate the implementation of IFP under the premise of forming a consensus. However, ABC’s political experience and capabilities are severely lacking, and it naively took the wrong step of pushing IFP. It not only broke with IFP opponents, but also caused some IFP supporters to firmly oppose ABC and turn to support BCHN, including Jiang Zhuoer and myself.
It can be said that the naive behavior of ABC directly led to this fork of BCHA. When ABC wrote the immature IFP into the code and announced the upgrade on November 15, the fork has become irreversible. Because, for most people, this IFP version is unacceptable, and it is difficult to withdraw the announcement once it is published.
3. Harmonious bifurcation suggestion
Realize that forks are inevitable. On August 27th, I issued the “BCH Rational and Harmonious Bifurcation Proposal” to the community. (Https://read.cash/ ProfLiu/the-suggestion-for-the-rational-and-harmonious-fork-of-bch-cca9fb96)
In my opinion, since the fork is inevitable, we should try our best to make the fork proceed peacefully and determine the details of the fork as soon as possible to reduce uncertainty and the consumption of mutual attacks. The fork of the decentralized ecology is inevitable, and the establishment of a harmonious fork mechanism through this fork is more important for the orderly evolution in the future. This is the same as the meaning of a peaceful presidential election instead of bloodshed to change dynasties.
I suggest that BCHN and ABC put aside the most acute naming rights dispute, first reach a consensus on a harmonious fork, and sit down and talk. During the negotiations, the focus was on resolving the issue of naming rights. Once the issue of naming rights is resolved, other issues will be resolved, and ecological stability and the protection of user rights can also be achieved.
This proposal has been approved by some important members of the ecology, but the key war parties, BCHN and ABC, are firmly opposed. They both think that the other party is a bad person and should be driven out of the community. Both parties have firm convictions and are unable to waver.
Harmonious bifurcation cannot be achieved, which can reduce the uncertainty and intensity of the struggle. The key to reducing the ecological damage of BCH is to determine the naming rights as soon as possible.
For this reason, I suggested to Yang Haipo to launch BCHN and BCHA futures trading, and clearly name the higher price before the fork “BCH”. At the end of September, Coinex launched two futures trading pairs and announced the strategy of naming the higher bidder BCH. At that time, the BCHA/BCHN ratio was roughly 0.17.
As the transaction unfolded and other exchanges followed up, the situation gradually became clear. BCHA/BCHN all the way down from 0.17 to 0.05. The naming dispute is basically no more suspense. In early November, the ABC team announced the release of a version that supports BCHN, and is willing to hand over the management rights of the BCH official website bitcoincash.org, and mark the ABC chain as BCHA. The naming dispute has ended before the fork.
At this time, the suspense left is whether BCHA can survive the fork.
4. The birth of BCHA
On November 15th, at the height of block 661648, the moment of the fork came, the price of BCHN was higher, and the supporting computing power was also greater. The block was successfully produced after 3 minutes at block 661647. However, the price of BCHA is only about one-tenth, and the difficulty of the two chains is the same when forking. Therefore, mining BCHA means a loss of 90%.
If no one is responsible for mining the first dozens of blocks at a loss, the difficulty will never be adjusted, and the BCHA chain will fail to produce blocks and will die.
After 1 hour and 40 minutes, block 661648 of BCHA was finally born. Miners left a message on coinbase “Very good mining pool/ABC/”. It seems that foreign miners are thanking Chinese mining pools. Yang Haipo’s Viabtc mining pool has announced that it supports BCHA mining, and the thanks may be given to him.
It took about 6 days for BCHA to return to normal block time. For 100 blocks from 661647 to 661747, it takes only 17 hours under normal circumstances, while BCHA exceeds 5 days.
The founding miner dug the 22 most difficult and loss-making blocks from 661648 to 661670, which is not a small expense. Starting from block 661671, the anonymous founding miners stopped mining, and the miners whose coinbase marked “/ViaBTC/Mined by bucher/” continued to produce blocks.
5. Proposals for peaceful development
From early August to November 20th, due to the uncertainty and community friction caused by the fork, the price of BCH continued to fall, and the price of BTC kept breaking new lows. From the lowest of 0.0282 on August 2 to 0.0135 on November 18, it fell by half.
As BCHA tends to produce blocks normally, the fork seems to have settled, eliminating mutual interference, and both parties should invest in their respective construction as soon as possible.
For this reason, I released “BCH Post-Fork Recommendations” (https://read.cash/ ProfLiu/suggestions-after-the-fork-of-bch-bch-a2a853a6) on November 19th, mainly including:
1) It is recommended that both sides stop hostilities and develop independently.
2) After BCH completes some consensus items in the next upgrade, the hard fork time will be changed from half a year to 3 years to maintain ecological stability.
3) The market value of BCHA is relatively small, and it can maintain the hard fork upgrade for half a year and test governance mechanism improvements.
4) For the successful improvement of the BCHA test, BCH was introduced in the hard fork upgrade 3 years later.
This proposal did not receive a response from both parties. In fact, an attack is brewing.
6. Empty block attack and dust attack
As BCHA’s block production stabilized, on November 20th, the attack on BCHA began. At 22:45, the attacker dug up 661684, which is an empty block with only new currency issuance transactions and no other transactions. At the same time, the attacker sends a large amount of garbage transactions of about 0.002 to fill the memory pool.
The reason why the attacker did not use the common 51% attack of POW to reorganize the BCHA chain is because BCH adopted a reorganization protection strategy in the BSV defense battle, and the reorganization of more than 10 blocks will not be accepted by the node. In this way, as long as the exchange requires more than 10 confirmations, the double-spending attack cannot succeed. At that time, it directly repelled the 51% attack threat from CA and CSW.
The attacker adopts empty block attack + dust attack to keep empty blocks continuously, so that normal transactions can never be packaged, thereby destroying the normal transfer function of BCHA. Dust transactions try to congest the node memory pool and further hinder normal transfer and block production.
The attacker left a message on coinbase “Nov 25th 2020/”, which was later changed to “Nov 25th 2020: bcha dump|voluntarism.dev”, which seemed to be based on a voluntarism stance and threatened the market to sell BCHA in large quantities on the 25th.
After playing 15 empty blocks in a row, the defense began. At 3:31 on the 21st, 18228 transactions were packaged in the 661700 block with a size of 8M and a total miner fee of 0.3BCHA. Coinbase left a message “/ViaBTC/Mined by goatpharmer/”.
7. Suggestions to stop the attack
From the 20th to the 24th, the offensive and defensive sides were deadlocked. The attacker played most of the blocks, and the defender kept producing blocks. Each block was 8M and nearly 20,000 transactions were packaged.
In my opinion, empty block attacks and dust attacks are unprofitable irrational behaviors, and they are also difficult to succeed. On November 24th, I published the “Stop Attacking BCHA” recommendation on read.cash. The main reasons are:
1) The attacker consumes more than the defender, and the defender only needs two hours to come over and make a block.
2) Dust attacks each block to bring about 20 yuan in fee income for the defender.
3) There is no fierce community confrontation like the bsv fork, and there is no need to launch an attack.
4) In the absence of community confrontation, many people are dual-wielding. Attacks will cause everyone’s losses and are unpopular.
5) As long as there is support for computing power to issue a block package transaction every two hours, bcha will not be killed and the attack will be futile.
6) The ABC team continues to develop bcha, which has reference significance for bch, and is better than forcing them to abandon development or turn to closed bsv development.
7) If bcha is really killed, it is actually telling core fans and bsv fans that bch can be killed in the same way.
After the recommendation was released, at 4:36 on the 25th, starting from block 662116, the empty block attack stopped. The attacker’s 4M block and Viabtc’s 8M block cleaned up garbage transactions in the memory pool. Some other mining pools, such as ming-dutch, have also joined normal mining.
I once thought that the attacker had regained his rationality. But at 21:23 on the 25th, starting from block 662135, empty block attacks and dust attacks started again. Coinbase left a message “Nov 27th 2020: run the numbers|voluntarism.dev”, leaving an identity “voluntarism.dev”.
The attacker changed coinbase to Chinese “regardless of black hash and white hash, what can protect the interests of miners is a good hash”. This is a variant of Jiang Zhuoer’s commonly used cat theory. But this behavior does not conform to Jiang Zhuoer’s rational habits, and Jiang Zhuoer himself clearly supports harmonious bifurcation. This coinbase message seems a bit intentional.
8. Orphan block attack
Orphan block attack, when the attacker receives the block of the normally packaged transaction, immediately use greater computing power to hit two consecutive empty blocks to isolate the normal block. This is a small reorganization attack or 51% attack. The purpose is not to double spend, but to prevent the normal packaging of transactions.
After the attack resumed, ViaBTC continued to produce blocks normally, and normal transactions could be packaged within three or four hours.
On the 27th, the attacker Voluntarism.dev tweeted an attack threat: anyone who dares to mine the BCHA block will be isolated unless the block reward is 100% given to the ABC fund address. And given the code to teach miners how to increase the fund ratio from 8% to 100%.
Weibo blogger Bruce Lee reposted this threat and believes that in the face of this solitary block attack threat, it is impossible to protect BCHA from a large loss of computing power. ABC can only change the algorithm, or even change the pos.
On the 28th, the orphan attack occurred. After viabtc dug out block 662397, volunteerism.dev quickly dug out 662397, 98 and 99, and invalidated the 97 of viabtc.
However, the defender is also prepared. The anonymous defensive miner then used massive computing power to connect 12 blocks on the basis of viabtc’s 662397, isolating the attacker’s 3 blocks again, and more than 10 blocks will not be repeated. Was reorganized. An anonymous defensive miner posted “/voluntarism.dev,aka asicseer.com and u/ugtarmas, is a bully/” on coinbase, calling the attacker a “bully”.
This offensive and defensive battle ended with the defeat of the attacker Voluntarism.dev. Some people in the bch community believe that the asicseer.com mining pool is behind Voluntarism.dev, whose CEO is Alexander Levin Jr, and the id on reddit is u/ugtarmas.
9. Get together and “defend” it
After the solitary block attack failed, Voluntarism.dev temporarily gave up the solitary block attack that was too costly to fail, and continued to take empty block attacks and dust attacks.
Continued attacks, especially solitary block attacks, aroused some people’s resentment in the mining circle. At the same time, the price of BCHA has basically remained stable. It is still profitable to dig BCHA. Instead, the number of miners mining BCHA has increased.
From 28th to 29th, at least 5 mining pools or independent miners including anonymous defensive miners, viabtc, and ming-dutch participated in the defense of BCHA.
Anonymous defensive miners only pack normal transactions and do not pack dust attack transactions. The block is within 100k. Voluntarism.dev is called “bully” in coinbase, such as block 662406.
Viabtc mining pool packs 8M blocks, about 20,000 transactions, and different miners output. For example, 662453 is played for miner mminer55.
The Mining-Dutch mining pool packs 2M blocks, such as block 662454.
The Bcha.pro mining pool packs blocks within 1M. Such as block 662464.
Another anonymous mining pool packs 32M blocks, each including more than 75,000 transactions, and the transaction fee is as high as 1.5BCHA, which is the main force for digesting dust transactions. Such as block 662450.
At 11 o’clock on the 29th, the empty block attack on BCHA stopped, and blocks began to be produced normally at 662447 altitude; at 6 pm, at 662462 altitude, the dust transaction in the memory pool was cleared.
The offensive and defensive war came to an end again.
10. The price of “freedom”
At 7:57 on November 30th, block height 662589, empty block attacks and dust attacks began again. This time the coinbase message was changed to “evoluntarism.dev:6174 x/x|the price of freedom”.
This message indicates that 1) the attacker wants to put BCHA to death; 2) the attacker has paid a significant cost for the continuous attack; 3) the motivation of the attack is based on the concept of liberalism or anarchism, opposed to output from the block Extract governance funds from the
The PoW ecosystem has long established the practice of extracting funds from block output. Dash and ZEC have been running for many years, and no one has launched a computing power attack. The attacker’s attack on BCHA is fundamentally due to the hatred generated by ABC during the process of pushing IFP.
At this point, the attack has shown obvious irrational characteristics and has become an action based on belief and hatred, more of hatred. This kind of attack itself uses violence to force consistency and kill the forked chain, which violates the spirit of liberalism.
Under the belief of “the price of freedom”, the attacker adjusts the attack strategy again and implements “empty block attack + dust attack + isolated block attack” with greater computing power:
1) The attacker first attacks with large computing power and high-cost empty blocks to keep the difficulty high and drive away normal miners. For example, from blocks 662721 to 662740, 20 blocks are produced in 34 minutes, and the average block interval is only 1:47 minutes.
2) After the difficulty increases, stop mining, wait two or three hours, continue to start large-scale mining, and adjust the difficulty.
3) If a normal packaged block occurs, a 51% attack with large computing power will isolate the block. On the afternoon of December 1, 6 Viabtc blocks were isolated.
The attacker does not hesitate to pay, how should the defender respond?
11. Computing power VS consensus
Under the attacker’s powerful computing power attack, the BCHA block from each browser on the evening of December 1 stayed at the attacker’s block 662658, and no new blocks were generated.
On December 2, ABC urgently released version 0.22.8, set a checkpoint, discarded the attacker’s 662687 block and the attacker’s empty block, and packed the new 662687 block with defensive computing power, and based on this block. Form a defensive chain.
However, at this time, the main browsers of BCHA, such as blockchair.com and viawallet, stopped at block 662658 of the attacker. BCHA’s exchange also did not switch to the defensive chain. Coinex announced the suspension of deposit and withdrawal. The attacker seems to be about to succeed.
On December 2nd, evoluntarism.dev issued a harsh truce on Twitter:
1) The sha256 mining algorithm is no longer used.
2) The full name of the coin cannot contain “bitcoin”.
3) The code name of the coin cannot contain “bch”.
Except for the past mentioned in the third article, the first two are very excessive. In fact, there are dozens or hundreds of coins named “bitcoin” and sha256 algorithm in the market.
When ABC had given up the name of bch before the fork, and handed over the management of the official website, this request was completely a gesture of surrender.
However, whether the attacker’s chain is longer or appears earlier. The attacker is the attacker after all. Even if ABC lost most of his supporters in the BCH community, he still has his own supporters. As long as ABC and his supporters don’t give up, the future of this coin lies in ABC and supporters, not attackers for browsers, exchanges, and mining pools.
On the afternoon of December 2, BCHA’s main browsers such as blockchair and viawallet completed the node update, starting from block 662687 to update the defender’s chain. As of press time, the attacker’s empty block did not appear again.
Many strong supporters of PoW believe that BCHA does not abide by the longest chain rule and is developer-centric, mocking it as “Prove of Developer”. However, as long as someone develops and maintains, has supporting computing power, has supporters, has browsers, exchanges and other infrastructure support, computing power is difficult to kill a decentralized cryptocurrency. Consensus that computing power cannot kill.
12. Outlook of offensive and defensive warfare
Generally speaking, this offensive and defensive battle is not necessary because the naming dispute was resolved before the fork. ABC gave up the name of BCH and even handed over the management of the official website. This is completely different from the fierce competition between the two sides when BSV split in 2018.
The overall loss of this offensive and defensive battle is not large, which is determined by the nature of the attack.
The 2018 BSV fork was due to the CSW threat to carry out a 51% reorganization attack on BCH. Both the defender and the attacker have accumulated a large amount of computing power, which far exceeds the output income, and the total daily consumption is more than one million yuan. This dealt a heavy blow to the entire market in the cold winter of 2018.
In this offensive and defensive battle, both sides generally maintained their normal computing power, and only used a large amount of computing power when attacking isolated blocks. The price of BCHA has not fallen sharply either. Therefore, the loss of mining revenue is not large. This is also the reason why the offensive and defensive war can continue.
The offensive and defensive model determines that the attacker is at a significant disadvantage in terms of economic benefits. This is a huge difference from the 2018 fork.
In 2018, in order to avoid the 51% reorganization attack on BCH, the defender must maintain a large amount of computing power and continue to lose. The attacker does not need to attack all the time, but can launch an attack at any time. It can be said that the defender is in the light and the attacker is in the dark.
In this offensive and defensive war, reorganization protection eliminates the threat of 51% reorganization attacks. The attacker can only take empty block attacks, dust trading attacks, and isolated block attacks. The situation is reversed, that is, the attacker must continue to pack empty blocks to maintain dust transactions in the memory pool, while the defender only needs to pack a large block every few hours, pack a large number of transactions, and obtain additional transaction fee income.
Therefore, in this offensive and defensive war, the attacker is in the light, the defender is in the dark, and the attacker is passive. In order to prevent the defender from generating blocks, the attacker also needs to increase its computing power to make mining at a loss. This is a method of hurting 800 people and self-damaging 1000. This asymmetric offensive and defensive warfare that is not conducive to the attacker continues to consume the attacker’s resources.
Even if the attacker is based on hatred, regardless of reason, and does not hesitate to attack at his expense, the defender can still discard the attacker’s chain based on consensus or adopt other temporary measures to resist computing power attacks.
Because BCHA has a core development team, firm supporters, and its own consensus community. In addition, there is a huge market for trading on many important exchanges. As long as the price is low enough, there will be a large number of purchase orders, miners will be able to get profits, and there will be normal miners mining.
Therefore, as long as ABC does not give up and supporters do not give up, BCHA cannot be killed by computing power.
This is the huge difference between the information world and the material world. The material economy can completely kill the enemy through physical elimination, while the information world cannot kill the opponent through computing power. A true victory requires a greater consensus to create value in the market.
13. Fork Wars and the Evolution of Cryptocurrency
Regarding decentralized cryptocurrency as an innovative experiment that is constantly evolving, from the expansion fork in 2017, to the BSV fork in 2018, to this offensive and defensive battle, all three forks have revealed important issues with centralized cryptocurrencies.
The main problem exposed by the expansion and fork in 2017 is the governance problem of the decentralized ecology. This problem has not been solved and it continues to appear in new forms. The 2018 fork showed that it is difficult for the decentralized community to resist organized centralized attacks. This offensive and defensive battle is even more directly caused by the exploration of a new governance model (IFP).
The 2018 fork presents another important question: Does decentralized cryptocurrency need to evolve, or should it return to the classics to maintain stability? A large number of people who support CSW, especially developers, are officially attracted by CSW’s return to the classic route.
This offensive and defensive war also revealed a deep-seated question: Should the minority survive? I mentioned this question in both wars in 2016 and 2018. I think that since it is an innovation field, it is difficult to determine the path to success. Major and irreconcilable differences should diverge. The minority after the fork should survive and retain one more possibility of success.
Regrettably, all three forks were filled with shouts and actions to kill the minority. Before it was BTC supporters and BSV who wanted to kill BCH, this time it became BCH supporters who wanted to kill BCHA.
During and after the BSV fork, the BCH community as a whole maintained a tolerant attitude, has been on the defensive, and has never launched a hashrate attack on the BSV chain. Why is it so harsh on BCHA this time? Confusing.
14. The value and enlightenment of offensive and defensive warfare
In the previous two bifurcation studies, governance issues and minority survival rights issues have become my focus. In the long run, I think this is the key to the success of decentralized cryptocurrency. If you can’t effectively govern while maintaining decentralization, the road to success will be very long.
To this end, I started looking for solutions in 2017, and got verification and inspiration from the evolution of BCH. In the Freecash (FCH) system launched on January 1, 2020, it inherited the successful experience verified by BTC, BCH and other cryptocurrencies, and also made some deductions and new designs.
In terms of governance mechanism, taking the prisoner’s dilemma of ABC and donors as a lesson, governance is divided into two levels: the first level, governance funds must be publicly output, and cannot rely on donations. The second level is to explore a decentralized governance fund operation model to prevent public funds from causing ecological centralization. The trial has achieved initial success.
In terms of consensus divergence and minority survival issues, the principle of free forks has been established, and the block-by-block difficulty adjustment mechanism (DAA) and reorganization protection of BCH have been inherited, so that the minority can survive the fork.
As a new chain adopting the SHA256 algorithm, it can be said that FCH has been an absolute minority since its birth. For this reason, FCH has made more changes to the Bitcoin framework. What is interesting is that these transformations and related deductions have been drilled and verified in this BCHA offensive and defensive battle.
For example, shorten the block time to 1 minute. This makes the difficulty adjustment speed of FCH 10 times that of BCH. Therefore: 1) The difficulty of BCHA is adjusted to normal 5 days after the fork, and FCH only needs half a day in the same situation. 2) When encountering an empty block attack or a difficulty bomb attack, the time for normal block generation and difficulty recovery, the defensive computing power requirement is reduced to 1/10.
Another example is to extend the maturity time of output. In this offensive and defensive battle, the attacker can sell the dug up BCHA on the market. FCH has designed a 10-day mining output maturity period and a 100-day governance fund maturity period. This makes: 1) the risk and attrition of the attacker greatly increased, and 2) the cost of killing the minority by the majority at the fork.
This offensive and defensive warfare exercise performed the empty block attack, dust attack, and isolated block attack that were considered in the FCH design. The attack is still in progress, and there are likely to be attacks and defenses that were not thought of before.
In addition, in the information world, the success of a decentralized ecology lies in the final analysis of a group of people who have common ideals and are willing to take action. If this consensus does not die, the ecology can continue. Establishing a consensus that can create value, share value, and benefit society is the source of power for survival and development. Our cognition should rise from the world currency to a free consensus.