Quote from: donlogan on Today at 03:34:43 AM

I did a search and it looks like the last time a QC topic was active was more than 3 years ago. That struck me as surprising because I though that QC could pose a threat to the security of BTC keys.

Google has been making exponential progress in the power of their QC machines. I believe I read an article saying that it is possible that within five years QC might be able to crack 128 bit encryption (the stuff bank websites use). I'm not that well versed in the technology of QC. It's just been something I've kept up with in relation to its possible effect on BTC.

Is the consensus here that QC will not be able to crack private keys?

Again this has been discussed countless time and user https://bitcointalk.org/index.php?action=profile;u=886521 has given a a good summation of some of the more recent discussions on Quantum Computing already in this thread.

My opinion is that Yes Quantum Computing(QC) does pose a threat to Bitcoin as it is today, but as QC technologies advance so will Bitcoin. Here is a quote From Vitalik Buterin "For every cryptographic algorithm that quantum computers can break, we know that we have a replacement [] that quantum computers cannot break."

Here are some easily available links On Quantum Computing and how it relates to Bitcoin

1) https://cryptobriefing.com/bitcoin-survive-quantum-computers/
2) https://en.bitcoin.it/wiki/Quantum_computing_and_Bitcoin
3) https://decrypt.co/28560/quantum-computers-could-crack-bitcoins-encryption-by-2022
4) https://cointelegraph.com/explained/how-the-crypto-world-is-preparing-for-quantum-computing-explained

Currently an Interesting idea being debated about are Lamport Signatures.

Which very briefly is a method for constructing a digital signature from any cryptographically secure one-way function; usually a cryptographic hash function is used.

Here is the math behind how it works if you are interested

Keys

Let k be a positive integer and let P={0,1}k be the set of messages. Let f:Y→Z be a one-way function.

For 1≤i≤k and j∈{0,1} the signer chooses yi,j∈Y randomly and computes zi,j=f(yi,j).

The private key K consists of 2k values yi,j. The public key consists of the 2k values zi,j.

Signing a message

Let m=m1mk∈{0,1}k be a message.

The signature of the message is sig(m1mk)=(y1,m1,,yk,mk)=(s1,,sk).

Verifying a signature

The verifier validates a signature by checking that f(si)=zi,mi for all 1≤i≤k.

In order to forge a message Eve would have to invert the one-way function f. This is assumed to be intractable for suitably sized inputs and outputs.

Source: https://cryptography.fandom.com/wiki/Lamport_signature
Source: https://www.geeksforgeeks.org/lamport-one-time-signature-scheme/

I would also highly Implore you to go through both these links for a clearer understanding on Lamport signatures. Also if anyone else over here could kindly share their views on it it would be very helpful.

Also could anyone shed some insight on QC in relation to mining.( I guess this shouldn't be an issue assuming most miners are using QC for mining but couldn't this lead to massive centralization)

Thoughts?