Can Quantum Computers Hack Bitcoin?!?

So, when can a quantum computer destroy bitcoin?

Or can it at all?

And if it can, when should we really start worrying?

In this video, I’m going to talk about quantum computings potential impact on bitcoin.

There’s two things that people are concerned about. The mining, and the transactions.

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0:00 Can quantum computers break bitcoin?
0:27 The blockchain & mining
1:07 Can quantum computers mine bitcoin faster?
3:17 Can quantum computers affect bitcoin transactions?
5:44 Vulnerabilities to quantum computers in BTC - Public Key
6:38 DO NOT REUSE WALLETS
7:16 Attacks during confirmation of transactions
8:34 Lost Private Keys
9:28 Post quantum cryptography
10:19 How many qubits for quantum computer break bitcoin?
11:05 How long until we have a big enough quantum computer?
12:05 Looking forward to a quantum computing future
12:49 Do I own bitcoin?

How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits: https://arxiv.org/pdf/1905.09749.pdf

Quantum Resource Estimates for Computing Elliptic Curve Discrete Logarithms: https://eprint.iacr.org/2017/598.pdf

John Preskill - Introduction to Quantum Information: https://www.youtube.com/watch?v=Q4xBlSi_fOs

Chart/Tweet on Bitcoin private keys:
https://twitter.com/marcotomamichel/status/989843515759738881

Can quantum computers mine bitcoin faster?

Quantum computers do not “brute force” SHA-256 faster, or parallelize the process more. There is no known quantum algorithm that can “undo” SHA-256 hashing to “guess” the correct nonce needed.

Let’s say we did discover a quantum algorithm that could figure out this hash faster..

Bitcoin is designed to adjust the difficulty required to mine blocks. So even if that happened, the difficulty would be adjusted.

Of course, if we did have that algorithms, quantum mining was a lot more effective, perhaps only people with quantum computers would have likely have the chance to actually get those coins. It would really depend on the quantum algorithm. This is why mining with just your computer is really not practical at this point, because people are mining with ASICs much more efficiently suited to this problem.

The second part people worry about is how can quantum computers affect the actual spending and transactions of bitcoin and other cryptocurrencies.

Of course, the elliptic curve crytography has been under scrutiny since the quantum computing hype began.

Two of the most common cryptosystems are Rivest–Shamir–Adleman (RSA) and elliptic curve cryptography (ECC). Both of these are vulnerable to attacks by quantum computers. A large enough quantum computer will become a security problem for anyone interacting online.

Bitcoin uses elliptic curve encryption to generate the public key - which is shown publicly - from the private key that authorizes spending.

First, a malicious actor would need to find the public key. While the wallet address is based on the public key, it’s hashed by algorithms that currently are not vulnerable to quantum computing attacks. However, during a transaction, the public key is exposed.

However, one mitigation is the hierarchical deterministic wallet, which is now the standard for most mature exchanges. Their wallets allow you to have many wallet addresses. This means that once the private key is used for a transaction, all the coins move, and that key is no longer valid.

However, not all exchanges do this. Some reuse wallet addresses!

If they reuse wallet addresses, the private key can be used again to sign a transaction. That means a transaction long in the past could be used to recover the private key, and then that private key could be used again today to move coins.

Even if we do not reuse addresses, there’s an argument to be made that there’s still time during the transaction to intercept the coins.

How big does this quantum computer bitcoin killer need to be to actually affect cryptography though? Microsoft Research has shown fewer qubits are needed for computing elliptic curve discrete logarithms – as few as about 2500 for a standard 256-bit key than 2048-bit RSA, which needs 4000. However, these are perfect, “logical” qubits. Because of error correction and other necessary processes, we need many more physical qubits. John Preskill noted in his lecture on quantum information that a 10 million physical and 10,000 logical qubit quantum computer would be needed

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#bitcoin #cryptocurrency #quantumcomputing

Видео Can Quantum Computers Hack Bitcoin?!? канала Anastasia Marchenkova