Quote from: mixoftix on November 25, 2018, 09:51:56 AM

Quote from: tromp on November 25, 2018, 08:34:35 AM

Quote from: bones261 on November 25, 2018, 07:04:16 AM

I think if we are at the point in technology that a QC can be made that can break SHA256 in a relatively trivial manner

Wrong; quantum computers need to run for 2^80 steps to find a private key mapping to a given 160 bit public key. That will remain infeasible for decades to come.

however the threat of QC is 51% attack, not directly breaking the key-pairs but while cryptographers think in probability space (2^80) of breaking something secure (in theory), there are Cryptanalysis methods out there to find shortcuts (in practice) and decrease the steps they need to pass:

https://en.wikipedia.org/wiki/Cryptanalysis

the most important point of failure that I see in asymmetric encryption is running a Random Function in key generation stage. providing real randomness is one of the hardest problems that I ever seen - because what you think is random at first sight, in fact carries a hidden pattern inside. so most of the time random number generation is where Cryptanalysis begin their job from.

Wrong. There is no shortcut for sha2 and if it would be ever possible to find such a shortcut the whole bitcoin blockchain security will become void and you don't need to wait for QC to bring it down.