Does Satoshi have a million bitcoin?

Abstract: We examine the extent to which one miner dominated Bitcoin in 2009. We review Sergio Demian Lerner’s 2013 analysis, where he discovered that the increase in the ExtraNonce value in the block can potentially be used to link different blocks to the same miner. We build on his analysis and conclude that although the evidence is far less robust than many assume, there is reasonable evidence that a single dominant miner in 2009 could have generated around 700,000 bitcoin. Although our analysis itself is weak and there is no perfect way of approaching this problem.

Bitcoin blocks mined in 2009 – ExtraNonce vs block height


 (Source: BitMEX Research, Bitcoin blockchain)

The history of the debate over the dominant miner in 2009

Towards the start of April 2013, blockchain researcher Sergio Demian Lerner attempted to argue that Satoshi had mined a million bitcoin in 2009. The logic behind this assertion was that the hashrate throughout 2009 was at a low level, around 7 million hashes per second and this was said to be consistent with one miner being highly dominant. At the same time this hashrate was around the same to that which was present in Bitcoin’s first 14 days, which Sergio assumes may be a period in which Satoshi was the only miner. Many in the community were sceptical of Sergio’s claims. The scepticism seems to be based on the following:

    The 7 MH/second estimate is based on block timestamps and unreliable, nor is the sample size large enough
    There is no reason to believe Satoshi mined alone in the first 14 days
    Many individuals recalled mining themselves in the period
    Sergio’s assumptions about hardware were incorrect

It is likely that some people could have been biased in dismissing Sergio’s claims, since if Satoshi had mined a significant proportion of the early coins, in the eyes of some that could damage the monetary integrity of the system. However, in our view, the evidence Sergio initially presented was somewhat weak.

The ExtraNonce bombshell

Just a few days later, Sergio then posted a far more persuasive argument on his blog, with much stronger evidence that a single miner was dominant. This then eventually convinced many in the community and to this day many people believe Satoshi is likely to have mined around one million bitcoin.

Sergio’s evidence centred around something called the ExtraNonce. The ExtraNonce is not part of the Bitcoin protocol, in that it is not part of the consensus rules nor is there a formal specification about how to interpret the field. The ExtraNonce is an area in the Coinbase transaction which can vary after several hashing attempts to provide extra entropy for miners, once the standard nonce in the block header has been used up. As the image below illustrates, as the ExtraNonce changes, the impact works its way up the merkle tree into the block header (although in 2009 most blocks contained only the Coinbase transaction, as the network was not used for transactions.)












(Illustrative diagram of the structure of a Bitcoin block)

Sergio published the below picture, with the ExtraNonce on the y-axis and the blockheight on the x-axis (He incorrectly labeled the x-axis as time). The image shows that the ExtraNonce increase over time, in a series of slopes. Some of the slopes (in black) are said to be of a similar gradient, not to overlap and to go back down to zero once they reach a certain height. This is said to demonstrate that all the black lines belonged to one miner (potentially Satoshi) and that this miner now controlled almost a million Bitcoin. Although the technical points about the gradient of the slopes, the height and the lack of overlap may be quite difficult to appreciate and evaluate, the image itself is clearly very powerful and persuasive, in our view.(Illustrative diagram of the structure of a Bitcoin block)

Sergio published the below picture, with the ExtraNonce on the y-axis and the blockheight on the x-axis (He incorrectly labeled the x-axis as time). The image shows that the ExtraNonce increase over time, in a series of slopes. Some of the slopes (in black) are said to be of a similar gradient, not to overlap and to go back down to zero once they reach a certain height. This is said to demonstrate that all the black lines belonged to one miner (potentially Satoshi) and that this miner now controlled almost a million Bitcoin. Although the technical points about the gradient of the slopes, the height and the lack of overlap may be quite difficult to appreciate and evaluate, the image itself is clearly very powerful and persuasive, in our view.