Bitcoin is trusted by governments and monetary establishments. Outstanding traders name it “digital gold,” and a few even declare it is higher than gold. Regardless of all this, Bitcoin nonetheless faces varied safety threats. Lots has been mentioned just lately concerning the potential risk of quantum computer systems. Nonetheless, Professor Campbell Harvey of Duke College revealed one other concern: 51% assaults towards the Bitcoin community are comparatively low cost.
abstract
- If profitable, a 51% assault would permit an attacker to take management of the Bitcoin blockchain (or one other proof-of-work based mostly blockchain). To achieve success, an attacker should management over 50% of the mining hash charge, which comes at a price.
- Previously, Bitcoin Gold and Ethereum Traditional skilled profitable 51% assaults leading to coin theft resulting from double spending. All through historical past, the Bitcoin blockchain has remained safe from 51% assaults.
- In keeping with Harvey, to monopolize hashrate era for per week, an attacker would want to spend “solely” $6 billion, lower than 0.5% of Bitcoin’s market capitalization. Harvey offered the opportunity of sensible use of such an assault.
Campbell Harvey, a professor at Duke College’s Fuqua College of Enterprise, revealed a paper targeted on potential threats to Bitcoin. in abstractThough Harvey likens Bitcoin to gold, he outlines that Bitcoin faces distinctive threats from quantum computer systems and, extra importantly, the opportunity of a 51% assault. He additionally acknowledges that Bitcoin has benefits over gold. For instance, he says that whereas “fashionable alchemy” permits for the manufacturing of extra gold, the availability of Bitcoin can’t exceed 21 million models.
What’s a 51% assault?
Mining Bitcoin is dear and requires particular {hardware}, so miners haven’t got the chance to tinker with ledger knowledge. Every node “votes” by way of its computing energy (hashrate) to validate transactions for brand spanking new blocks, and nearly all of miners vote for proper knowledge. Miners depend on the integrity of the Bitcoin blockchain, in order that they have an incentive to vote for proper knowledge, which brings worth.
Nonetheless, as soon as half of the full hashrate within the system is managed by a single entity (both a person or a bunch of plotters), it has the facility to vary the information on the Bitcoin ledger. This enables malicious events to maneuver another person’s Bitcoin and basically steal their Bitcoin.
Some individuals criticize Bitcoin, however low level of decentralization; Within the 16 years since Bitcoin was created, nobody has been capable of management the Bitcoin blockchain.
Within the early days of Bitcoin, mining was accessible to any PC proprietor. Nonetheless, as a result of mining is predicated on competitors and requires the luckiest miner to have the next hashrate stage than most of their rivals, computer systems, and even GPUs and FPGAs, rapidly turned out of date for mining. In 2013, the primary ASICs (gadgets specialised for Bitcoin mining) appeared available on the market. Bitcoin mining quickly become a multi-million greenback business, requiring important funding and tools crammed with whirring ASIC gadgets. In October 2025, Bitcoin mining problem reached a brand new excessive.
This makes hacking Bitcoin with a 51% assault a tough and costly process. As the problem of mining will increase, the price of a 51% assault additionally will increase yearly.
Campbell Harvey’s Discovery
51% assaults are pricey, however the associated fee shouldn’t be unimaginable. Networks like Bitcoin Gold and Ethereum Traditional have suffered a number of 51% assaults since 2017. In every particular person case, greater than 1 million cryptocurrencies have been stolen. In August 2025, the Qubic mining pool claimed to have captured over 50% of the hashing energy of the Monero community.
Professor Harvey calculated the prices and concluded that it will value “solely” $6 billion to dominate the Bitcoin blockchain for one week.
“{Hardware} is the largest expense, about $4.6 billion at present costs. It could value $1.34 billion to construct the information heart, and about $130 million per week in electrical energy to run the {hardware} and keep the information heart. In complete, a weekly assault would value about $6 billion, or 0.26% of the full worth of the Bitcoin community.”
This examine is predicated on the next indicators:
- Annual manufacturing of Bitcoin is 164,363BTC
- Vitality consumption is 166.4TWh
- Whole value: $12 trillion
- Whole power value is $8.4 trillion
- Whole value per unit is $73,000 per BTC unit
Harvey identified that if the 51% assault on Bitcoin was profitable, the value would drop considerably and hackers may nonetheless revenue from it and get well greater than $6 billion. Harvey estimated the day by day quantity of BTC perpetual futures at $60 billion and the day by day quantity of conventional BTC futures at $10 billion. Harvey believes brief positions in these markets earlier than a 51% assault couldn’t solely return the $6 billion, but in addition generate important income for the attackers. Harvey added that the motive is probably not profit-related.
However critics of Mr Harvey’s warnings argued that organising such a large-scale mining operation would take years and wouldn’t be ignored. Greater than that, it might be tough to brief promote such a lot of BTC whereas the 51% assault continues. It is because there’s a excessive risk that the alternate will flag the operation as market manipulation and disallow it.
Matt Prusak, president of American Bitcoin, commented on Harvey’s analysis: said Bloomberg: “My angle is that financial feasibility invalidates the 51% principle. I stay in the actual world and I am not anxious.”
