Can Quantum Computing Take Over Bitcoin in 2020?
Crypto community has long been monitoring and discussing the possibility of crypto quantum computing taking over Bitcoin (BTC), especially over the past 12 months. As numerous questions and doubts arise, it is necessary to resolve some of them, clarifying issues which require attention and dissipating myths.
Will somebody steal our Bitcoin?
Many believe that Google’s 54-qubit computer Sycamore will be able to break into the system and snuff out everyone’s Bitcoin. This would happen in some 5 to 10 years, if action was not taken to change the existing implementation of Bitcoin blockchain. However, companies are recommended to start preparations.
What’s really alarming is that some people deny any possibility of this, and urge for the concern to be suppressed. This is a very naive belief. Collective efforts should be directed towards upgrading the complex distributed systems (doesn’t it sound familiar for blockchain enthusiasts?) to a completely new crypto stack. After a decade or two of massive growth the industry can be on the brink of extinction, if quantum computing will evolve to the expected level.
The fact is that current encryption algorithms used in Bitcoin and Ethereum systems have proven vulnerable to signature forgery which can be done with quantum computers.
Asymmetric algorithms, used in most blockchains, rely on keypairs (public and private keys), in which public key can be calculated from private one, but the reverse is impossible. This results from certain mathematic problems such as number factoring, which means decomposition of large numbers into a product of smaller multiplicands (in order to find the public key generator).
If the calculation can be done in reverse (i.e. finding private key from public one), the whole system collapses. To make such attacks executable we only need more qubits and stability in these systems.
Will Google mine all the Bitcoin left?
This questions also worries many people. In fact quantum computers are not so good at symmetric crypto-related computations, compared to asymmetric ones. For instance, traditional computer needs 2^128 operations to obtain private BTC key from public one, when quantum computer needs only 128^3 operations to do the same.
For hashing, the difference, though enormous, is far less. Anyway, we should be concerned more about people armed with quantum computers, who will try to steal our Bitcoin, then about Google mining all the remaining Bitcoin. Even if this happens, after mining 2016 blocks the difficulty will be set to ”quantum level” — and since then mining will be possible only for quantum computers.
The most interesting point here is that difficulty is already so high that miners often have to wait until the timestamp on their blocks will be readjusted, as they have already checked all nonces for the blocks below the difficulty level and failed to find the answer. Therefore, we can dare to say that mining problem is more theoretical than practical, because time is the key issue in mining, not performance.
A point which requires everyone’s attention
Should Bitcoin holders worry about quantum computing in 2020? No, but there is a warning: cryptocurrency developer teams and companies should take the issue into consideration.
What if somebody has managed to build a quantum computer which surpasses Google’s Sycamore? We can not be sure, since we are not allowed to know it.
We should focus on upgrading the existing blockchains and related systems (banks, governments etc.) to quantum-resistant crypto stack. Quantum dominance is inevitable — it is only a matter of time.