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Ethereum will not hide from quantum computers behind PoS shield

There are two mechanisms by which a quantum computer can violate a cryptoasset. Quantum computing is a threat that affects PoS and PoW equally. It is difficult to predict whether such a threat will emerge suddenly or gradually.

Quantum computing has long been considered the ‘bogeyman’ of Bitcoin (BTC). The popular fear is that just as secure as Bitcoin and other proof-of-work cryptoassets are in terms of standard cryptography, quantum computers could provide additional resources to break them.

Another popular assumption is that because they don’t use PoW, proof-of-stake cryptoassets such as Cardano (ADA), Polkadot (DOT), and Tron (TRX) (and possibly Ethereum (ETH)) are not as vulnerable to quantum computing. attacks such as networks such as Bitcoin, Bitcoin Cash (BCH) and Litecoin (LTC). However, according to several computer scientists and crypto experts, it is not a coin’s consensus mechanism that carries the greatest risk in terms of quantum computers, but rather its signature system.

In other words, since the vast majority of PoS cryptoassets also use (non-quantum) cryptographic signature systems to sign individual transactions, they are almost as vulnerable to quantum hacks as their PoW rivals. That said, the advent of sufficiently powerful quantum computers is still a long way off, while their emergence is likely to spur a widespread shift towards post-quantum cryptography.

51% attacks and signature attacks

The important point to make when considering whether PoS is less vulnerable to quantum computers is that there are two mechanisms by which a quantum computer could violate a cryptoasset:

The mechanism used to obtain the right to publish a block of transactions and to reach a distributed consensus (eg PoW or PoS)

The mechanism used to authorize individual transactions (usually with a public / private signature system)

It is the first mechanism to affect PoW more than PoS, with Bitcoin and other proof-of-work coins theoretically vulnerable to a 51% quantum computer-driven attack.

That said, Marek Naro?niak – a physics PhD student at New York University who has worked with Prof. Tim Byrne on research on quantum computers – explains that it’s still theoretical to talk about a 51% attack by quantum computers.

“If someone has a large enough quantum computer and wants to execute a 51% attack – consisting of outnumbering the remaining miners and producing invalid blocks – it should be a really huge quantum machine. This is because Bitcoin’s proof-of-work is based on a hash function for which there is no known efficient quantum algorithm [that it can reverse], ”he told

But while Bitcoin’s weakness compared to PoS cryptoassets is still quite hypothetical, quantum computing poses another threat that concerns PoS and PoW in equal measure.

Even if consensus does not require cryptographic ‘work’ [in the case of PoS], it still relies on cryptography that currently relies primarily on elliptic curves that are vulnerable to quantum algorithms. validators can break and still mess with the consensus, ”said Naro?niak. France Crypto website is popular.

This is a concern echoed by other commentators. In an analysis by Deloitte, Bram Bosch wrote that about four million bitcoins are stored in addresses that use p2pk and p2pkh scripting, which is vulnerable to attacks from quantum computers.

“Currently, about 25% of the bitcoins in circulation are vulnerable to a quantum attack. Even if someone’s own bitcoins are safe, someone can still be affected if other people will not (be able to) take the same safeguards, ”he told

Again, vulnerable scripting is something that can potentially affect both PoS cryptoassets and Bitcoin, even if quantum computers are far from being widely available. And even without older schemes like p2pk (h), Shor’s algorithm – a quantum computing algorithm – could be used to break many public key cryptography systems.

“If someone has a large enough and reliable quantum computer, it would be possible to crack the digital signature used to sign Bitcoin transactions. other people are transferred at will, “said Marek Naro?niak.

He addedn admits that the worst thing about this “is that it couldn’t even be detected”, and that PoS is just as vulnerable as PoW: “It would still be possible to produce transactions by breaking cryptographic signatures and producing transactions using someone else’s output. ”

Quantum-resistant solutions

Fortunately, current cryptographic research is more than aware of the theoretical threat posed by quantum computers, so you probably shouldn’t start selling all of your cryptocurrency just yet.

Researchers from Imperial College London published a paper in 2019 outlining a protocol that would allow Bitcoin users to move their money securely from non-quantum-resistant outputs to those who adhere to a quantum-resistant digital signature scheme.

In September 2020, Australian computer scientists from Monash Blockchain Technology Center and CSIRO’s Data61 developed what they described as ‘the world’s most efficient blockchain protocol that is … safe from quantum computers’.

So solutions seem to be available should a viable quantum computer emerge that could realistically be used to threaten PoW and PoS cryptoassets. And for most commenters, it is more likely that existing cryptos will switch to using post-quantum algorithms rather than new post-quantum cryptoassets that seem to take their place.

“I think the latest scenario of existing cryptocurrencies shifting to the use of post-quantum cryptography will be much more likely,” said cryptocurrency journalist and analyst Roger Huang. “It occurs to me that it will be much more difficult to rebuild the legitimacy, network effects and exchange / off-exchange volume of something like BTC from scratch than it is for BTC to adopt post-quantum cryptography alone.”

For Bram Bosch, it may be some time before the Bitcoin community (or any other) is forced to actually implement solutions to quantum computing risks. Italy cryptocurrency price prediction is popular.

“The threat of a quantum attack would have to be very clear and serious before the Bitcoin community could reach consensus on this. It is difficult to predict whether such a threat will emerge suddenly or gradually and as such whether there will be time to respond at all, ” he said.

That’s exactly what’s interesting about the danger of quantum computers: it’s an unknown, unpredictable quality. But since it is primarily a risk to the signatures used by virtually all cryptoassets, we know it will pose a threat to both PoS and PoW cryptos.