4 ms·
SHA2 hashing which secures the chain itself faces no known threats from quantum-computing. ECDSA wallet signatures can easily be broken with a sufficiently siz
by BelenusMordred 6y ago
SHA2 hashing which secures the chain itself faces no known threats from quantum-computing.
ECDSA wallet signatures can easily be broken with a sufficiently sized QC and now are essentially a billion dollar bounty on whether a country or corp has gotten there.
Switching over to post-quantum signatures is a simple matter but the coins will have to be moved to secure them.
So, someone with access to such a computer can learn the private key for any wallet on the planet and steal the contents, but they can't magically mine with 100% hashpower or undo history and all prior tx's.
- tromp 6y agoThe hashcash proof-of-work scheme that bitcoin uses is vulnerable to Grover's quantum search algorithm, that can find a solution in the 2^76 search space for the current target difficulty in roughly sqrt(2^76) = 2^38 quantum hashing steps, for a 2^38 factor speedup. Other proof-of-work schemes (e.g. finding cycles in graphs [1]) are not vulnerable to quantum speedup. [1] https://github.com/tromp/cuckoo https://github.com/tromp/cuckoo