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Quantum computing has long been seen as a possible existential danger to cryptocurrencies, with fears of broken encryption and hacked blockchains causing worry in the sector. Vitalik Buterin, one of the co-founders of Ethereum, has been a strong supporter of strong privacy safeguards. However, he also warns that the true danger is being too comfortable. Buterin wrote in a recent X article that real decentralisation requires giving consumers authority over their data, not just making it easier for people to utilise blockchain networks. “The purpose is not to get people to use Ethereum. He wrote, “The goal is to get people used to openness and self-sovereignty,” which showed how important it is to have mechanisms that don’t let central control happen.
As 2025 comes to an end, quantum developments have brought up old arguments about how weak crypto is. Microsoft’s announcement in February of the Majorana 1 chip, which they called “the world’s first quantum chip powered by a new Topological Core architecture,” has made some even more worried. However, most analysts agree that 2026 will not be the end of the world for Bitcoin or other big blockchains, despite all the hype. Cryptanalytic attacks won’t be possible for years to come. Instead, the most important thing right now is the “harvest now, decrypt later” tactic that enemies are using. They are already gathering encrypted data in case they make any future breakthroughs. This strategy is making the crypto community speed up its defences so that the sector is ready when quantum threats show up.
The Main Weakness in Crypto Systems
Public-key cryptography is used by most cryptocurrencies, including Bitcoin, to keep them safe. Private keys sign transactions, public keys check them, and hash functions keep the ledger safe. If a quantum computer were powerful enough, it might be able to figure out private keys from public ones, which would make it easier for thieves to steal money. Bitcoin and many other cryptocurrencies employ the elliptic curve digital signature algorithm (ECDSA). Shor’s algorithm, a quantum method that might solve the math issues behind ECDSA far quicker than classical computers, is especially good at breaking it.
Sofiia Kireieva, a blockchain expert at Boosty Labs, says that ECDSA would be the “weakest link” if a quantum enemy went after Bitcoin. On the other hand, hash functions like SHA-256 are stronger. Grover’s technique only speeds things up by a factor of two, which can be undone by greater hashes. Ahmad Shadid, creator of the O Foundation, says, “The ECDSA digital signature algorithm is the most vulnerable part of cryptography, especially when it comes to the security of public/private key pairs used to sign transactions, especially when addresses are reused.” This makes things more dangerous since reused addresses show public keys, which makes them easier targets for future decryption.
Kireieva says that 25–30% of Bitcoin, or about 4 million coins, are in addresses that are susceptible since their public keys have been made public. This data isn’t useful right away, but it could become very useful if quantum technology keeps getting better.
Experts’ Opinions on the 2026 Timeline
Even if there are theoretical hazards, it is quite unlikely that a quantum discovery that may overcome crypto encryption will happen in 2026. Clark Alexander, co-founder and head of AI at Argentum AI, says that quantum technology will have “extremely limited commercial use” next year, and it won’t be used for cryptanalysis. Coin Bureau analyst Nic Puckrin is less impressed: “The whole ‘quantum threat to Bitcoin’ story is 90% marketing and 10% imminent threat…we’re almost certainly at least a decade away from computers that can actually break existing cryptography.”
There are a lot of technical problems. Right now, quantum devices only have hundreds or thousands of noisy qubits, which isn’t enough for Shor’s method, which needs millions of error-corrected qubits to factor big integers. Kireieva says, “This would require breakthroughs in materials science, quantum control, fabrication, and signal isolation.” “Engineering isn’t the only thing holding things up; it’s the very physics of the universe.” Adam Back, the CEO of Blockstream and an expert in cryptography, agrees and says that Bitcoin won’t be at risk from quantum computers for the next 20 to 40 years.
Even the best-case scenarios from companies like IBM, which showed off sophisticated chips in 2025, say that real quantum threats will happen in the 2030s. Vitalik Buterin has said that quantum could affect Ethereum sooner than predicted, but he says that people should upgrade their software instead of panicking.
The Real Danger: Collect Now, Decode Later
There are still no direct attacks, but there is a more sneaky threat going on right now: “Harvest now, decrypt later.” Today, enemies including state actors, cybercriminals, and intelligence agencies are gathering encrypted data in the hopes that quantum decryption will be possible in the future. “Bad actors are already gathering as much encrypted data as they can… so that when the tech is ready, all that stored data can be read,” says Sean Ren, co-founder of Sahara AI.
This plan takes advantage of the fact that blockchains are public: People can easily collect transaction data, such as public keys. “One common attack scenario is ‘harvest now, decrypt later,’ where enemies are already gathering sensitive encrypted data to unlock when quantum breakthroughs happen,” says Nicolas le Jeune, CEO of Courtyard. Millions of Bitcoin addresses are still open since past transactions show public keys.
Governments are also involved. The U.S. SEC’s crypto task team got suggestions in September 2025 that warned of quantum threats and called for “harvest” defences. Switzerland’s data export rules and the UK’s online authentication requirements are examples of similar concerns that lead to these kinds of actions.
There Won’t Be an End of the World in 2026, but You Need to be Careful
The business isn’t sitting around. Experts in cryptography suggested in July 2025 that Bitcoin’s signatures be replaced with quantum-resistant ones, pointing out that 25% of funds were at risk. In November, projects like Qastle started using post-quantum encryption to protect hot wallets at the quantum level.
Ethereum is the leader in privacy-preserving transactions with ZKPs, and protocols like Alchemix V3 and X402 (Coinbase) have quantum-safe features. Kireieva says, “We need to minimise exposure by not reusing addresses, keeping public keys hidden until the money is spent, and moving to wallets that are resistant to quantum computing.”
There are bigger upgrades coming: Bitcoin’s Taproot (2021) included Schnorr signatures, which is a step towards quantum resistance. Ethereum’s Fusaka (December 2025) makes ZKP more scalable. “Harvest” knowledge makes things more urgent, even though full transformations could take years.
The future of quantum computing in 2026 doesn’t look very good: It can only be used for niche research because it has few qubits and significant error rates. It is far from breaking ECDSA. Ren states, “The chance of a major quantum attack happening in 2026 is low to moderate,” but “quantum becomes a top-tier risk factor for crypto security awareness.”
Crypto holders need to take proactive precautions, such getting fresh wallets and using protected transactions. Buterin warns that the goal is sovereignty. The challenges to the harvest in 2026 require planning now to protect networks in the future.
