Bitcoin uses a 256-bit encryption system based on the Elliptic Curve Digital Signature Algorithm (ECDSA). Breaking this encryption would require a quantum computer with over 1 million stable qubits - nearly 10,000 times more powerful than Willow’s current 105 qubits.
More conservative estimates suggest needing approximately 317 million physical qubits to crack a single Bitcoin key within an hour.
Seems it’s years away … plenty of time for BTC community to convert to something else - although with the investments of the mining community (in sha-256 ASIC’s) it will be a hard ask until the threat is closer.
This could be a helpful thing though - if they are forced to move away from sha-256, then they can adopt a much more decentralized and perhaps energy efficient means to mine, which would strengthen the network further. They could also switch up the block rewards to spread it out more in time and space. But I’m likely just dreamin’
Be aware though hashing and symmetric encryption are already quantum proof in terms of hardness.
The threat is the asymmetric algorithms, first those that rely on factoring prime numbers (RSA etc.) and then those that rely on logarithm methods (ECDSA or any ECC methods).
The signing mechanisms already have alternatives like FALCON etc. and it will be those that require upgrades when the time comes, if indeed it ever does.
Then there is AI already able to simulate quantum algorithms that are happening.
My opinion is that what will happen is bitcoin etc. will need to upgrade in a few years to a quantum proof algorithm and do a time limited hard fork (i.e. at a block number) the signing algorithm. Anyone who has not transferred the coins to that fork will lose them (including satoshi) as the old wallets will all be cracked, but for normal folk who hold bitcoin etc. the issue will be simply do a single transaction to a new wallet.
The miners can all still mine in SHA but the sig algorithm they use needs to update to ensure the transactions they validate are properly signed.
Satoshi used a huge number of addresses, with some estimates suggesting he could have more than 20,000 different addresses. He used a different address to receive each block reward, and since he was the most prominent miner in the early days of Bitcoin, he received a large number of block rewards.
I would expect them to go after the addresses that hold the most first. I guess that, as you say, simply moving them to a new address post fork will prove to be a viable solution. So only abandoned wallets will take a hit. Seems like it will still take some time to crack all of them though - especially Satoshi’s - given he has so many of them.
edit:
Would also imagine that Google or the US gov. would be the ones who would do it too as they will have first priority access to the tech. - and the US gov may see it as a strategic necessity to take control of them before anyone else to preserve the BTC market - given that so many in the US are invested in it.
So u saying that current quantum secure for autonomi will be cracked in a future? Or I understand incorrectly, and if no, what happens to data for example?
No, quantum secure is secure form quantum computing. There may be scientific advances in the future, we cannot tell, but chunks are information theoretically secure. i.e. it’s impossible to reverse any algorithm and crack them.
However we do use ECC sigs for Transactions/Pointers etc. and these would be under threat, but not data/chunks.