Last Sunday, August 15, 2021, the Foundry USA mining pool managed to mine 4 blocks of Bitcoin consecutively, as did the SBI Crypto pool, which confirmed 3 blocks in a row that same day.
Although it is not the first time that this has happened in the history of Bitcoin, it is more frequent today that a mining pool confirms only 2 consecutive blocks.
Foundry USA ranks fifth among mining pools with the highest processing power. The pool has 12.2 exahashes per second, 10% of the total power connected to the network, according to BTC.com.
SBI Crypto, meanwhile, is in 10th place, with 3 exahashes per second, 2.4% of the mining power connected to the network. Notably, both pools have been increasing their capacity this year, on an emerging basis, according to the data.
The blocks mined by Foundry USA were added to the chain at the height of 695,927, 695,928, 695,929 and 695,930, Kevin Zhang notified, vice president of Foundry, the pool’s parent company.
For its part, Carson Smith, CEO of SBI Pool, also reported on the hot streak of his group, which successfully mined the blocks 695,990, 695,991 and 695,992.
With the current block reward, the new bitcoins that are generated with each confirmed block, Foundry USA received 25 BTC, equivalent to USD 1 million 155 thousand, according to the CriptoNoticias price calculator.
For its part, SBI Crypto received 18.75 BTC, equivalent to USD 866 thousand. As we have explained in CriptoNoticias, said bitcoins do not remain in the hands of these companies, but are distributed among all the individual miners that are part of this pool, collectively uniting their power.
Curiously, block 695.930 contains a message alluding to the campaign and website WTFHappenedIn1971, regarding the fact that last Sunday they were fulfilled 50 years after the abolition of the Bretton Woods treaty, with which the then president of the United States, Richard Nixon, eliminated the support in gold for the dollar.
The Case for “Selfish Mining”: What Can Hide a Hot Streak?
There is no implicit risk of a Bitcoin miner confirming multiple consecutive blocks to their name, which it could be considered luck or chance.
However, the reiteration of this pattern among mining pools has caused suspicion in the past. In fact, it refers to a study published in 2013 by Ittay Eyal and Emin Gün Sirer, entitled “Majority is not Enough: Bitcoin Mining is Vulnerable”, or in Spanish “Most is not enough: Bitcoin mining is vulnerable.”
The study describes the attack of ‘selfish mining«, In which a miner obtains the solution to a block of transactions, and immediately abstains from transmitting said information to the rest of the miners on the network.
If then he manages to get the next block, while the other miners on the network continue working on the previous one, the “selfish miner” will be one step ahead of the rest of the participants.
This miner would always have the time to get a new block, to the advantage of his competitors, so that he could define the Bitcoin transaction history on his own, or reorganize the chain, imposing his version.
As the social consensus usually agrees in Bitcoin, the longest chain or with the most accumulated work, is usually considered as valid, a premise that would support the selfish miner since it did generate the Proof of Work (Proof-Of-Work, PoW) correct for the blocks you confirmed, but with reprehensible ethical practices.
On the other hand, it is not possible for the miner to work on two consecutive blocks at the same time, since to mine the second block he needs to know the previous one. Once the first block has been mined, and while looking for the solution of the second, another miner is much more likely to beat you.
Small and emerging pools would have incentives for selfish mining
Another study by the Blockchain Center of the University of Zurich (UZ), published in 2020, argues that selfish mining is a common practice among various pools, based on their findings. However, the authors think this is debatable.
In the first study, we have identified several very successful mining pools in continuously discovering two blocks in a row. We believe that the reason for this is that they use a selfish mining strategy, although it could be explained with a limitation in the time of dissemination of information about the blocks. In addition to that, our results show that selfish mining is very popular among lower income miners, and they do not use this technique continuously.
Blockchain Center, University of Zurich.
Foundry and SBI Crypto have grown to the top 10 most powerful pools in a short time, rubbing shoulders with the oldest and most established pools. Although the study indicates that these types of pools could incur this practice, these pools were not included in the sample studied, because by 2020 they still did not exist.
They also emphasize the possibility of a alleged “cartelization” of Bitcoin mining, where various pools would act in an organized way to continue engaging in more “selfish mining.”
The study has a quantitative approach, they limit, to offer another approach to previous research. It is very difficult to verify that selfish mining is taking place, but it is still an interesting concept to ponder.