Quote from: mixoftix on November 25, 2018, 10:41:02 AM

Quote from: aliashraf on November 25, 2018, 10:27:27 AM

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.

misunderstood. the SHA256 is not broken in output. what I wrote above is about the weakness in providing input for the SHA256 - because of weakness in random number generation. this is much more about vulnerabilities that exist in implementation stages of a secure platform - not the Math behind it. so we need to know how QC could influences in the structure of providing (and predict) input for SHA256 (or any other hash algorithm).

Now it makes a bit more sense but not enough. Again, it has nothing to do with QC:

If hypothetically, one could find such a vulnerability in the RNG used in a wallet, to be able to "narrow" the search space in brute forcing RIPEMD-160 hash he needs to:
1- 'Guessing' a 'more likely' private key (using the vulnerability in the Random Number Generator),
2- Performing one simple multiplication to compute a public key for it,
3- Generating ripemd-160 hash of the public key,
4- Praying for a match.

None of the above is QC related.