Quote from: hatshepsut93 on January 10, 2019, 02:33:15 AM

This article says that attacking Bitcoin requires 1500 qubits: https://en.bitcoin.it/wiki/Quantum_computing_and_Bitcoin

IBM Q System One has only 20, though they claim that they have better quality, meaning less errors.

Quote from: HeRetiK on January 09, 2019, 01:06:21 PM

Quote from: merclyn on January 09, 2019, 10:22:10 AM

I dont believe any quantum computers that are out or coming out anytime soon can break SHA256 yet.
When something like that comes out, we should have some time to react before it starts breaking things.

Dont forget that a computer that can break SHA256 is a huge threat to the entire internet, not just bitcoin.

For SHA256 there is currently no known algorithm that would give quantum computers an edge above classical CPUs, let alone ASICs.

Grover's algorithm? Not that it will break hash functions completely, but it will hugely reduce their security, so bigger hashsizes would be needed.

a hash is 32byte (64hex) which in binary is 256bit
which in qubits is 128qubit
(though an asic hash thousands of chips per asic.. and thousands of asics.. QC just has one chip)