Blockchain vs. Quantum-Computing – Is Quantum Computing a Threat to Crypto? | Hacker News Reader

Blockchain vs. Quantum-Computing – Is Quantum Computing a Threat to Crypto?

blockchain-council.org

5 pointsTrouble_00712 comments

If you could build a (quantum or classical) computer that takes years of computation to solve a single elliptic curve discrete log, then there's a neat way to profit. Compute d = log_G(H), where G and H are the generators used in Pedersen commitments.

Then you can undetectably print infinite amounts of money in coins based on Confidential Transactions (such as most privacy coins), by writing 0*H + r*G as v*H + (r-v*d)*G, where the former represents a coin of value 0 and the latter a coin of value v.

Not sure why this is often labeled a blockchain-specific problem. As the article points out, it’s the algorithms commonly used for public-key cryptography that would be at risk from quantum computing advances.

This means that online security itself would be threatened, which is a far bigger deal than the failure of cryptocurrencies. Blockchains would have to move to post-quantum cryptography, just like everything else.

The scary thing is if the mass surveillance is dumping encrypted missives to disk, waiting for future quantum decryption to unlock it all.

> Not sure why this is often labeled a blockchain-specific problem ... This means that online security itself would be threatened

In fact, all forms of security would be compromised. However, quantum cryptography is a thing. For example, China recently launched an actual, working, "ultra-secure" satellite communication system based on quantum crypto (https://www.scientificamerican.com/article/china-reaches-new...).

A fully realized quantum computer would be able to factor prime numbers in linear team using Shor's algorithm, and therefore would break the assumptions public-key cryptography at currently used key sizes. My rough understanding is that quantum cryptography is magic that provides an answer to this problem, so that if/when quantum computing is advanced enough to break all classical cryptography, there will also be a secure quantum based cryptographic capability to counter that threat.

I don't know if there is work on applications of quantum cryptography to blockchain specifically. Seems like a very interesting question.

Are star trek style teleporters a threat to bank vaults?

The difference is that quantum computers exist, while star-trek teleporters don’t (yet).

Bitcoin is safe from quantum computers for now:

https://physicsworld.com/a/bitcoin-encryption-is-safe-from-q...

But there is such a thing as post-quantum secure cryptography. It seems, however, the biggest risk is human.

>Timeline of Quantum Computing and Communication< : https://en.wikipedia.org/wiki/Timeline_of_quantum_computing_...

It is like asking - are Trolls a threat to Ogres ? Both these tech supposedly have fantastic super powers, but in their own imaginary worlds.

However Bitcoin - the only usecase that works, will be able to pivot to quantum resistant algorithms long before anything even starts becoming a threat.

Seems to be effing itself up just fine with classical computers.

Plain old math can be a threat to crypto. None of the popular algorithms are rigorously proven to be so hard to break as advertised (like NP or similar). Quantum machines can exacerbate this but it's not the only possibility.

NP isn't rigorously proven to be hard yet either.

Reply on news.ycombinator.com