XCGTech Just Solved the 51% Vulnerability that is found in every POW Coin.

[Matchveil]

When block 90,000 turned over, crypto was changed forever. The amazing Devs with XCG have now enabled their mid block difficulty re targeting. Making this coin 51% Proof!

Here is the actual code behind it too.

https://github.com/Xcgtech/Wallet/blob/master/src/pow.cpp

Here is an easier to read version of what they accomplished.

https://github.com/zawy12/difficulty-algorithms/issues/36

[aliashraf]

Op, Thanks for sharing. There are two points to be reminded tho:

1- It is not a 51% attack general mitigation, it is just about making harder for rental hashpower (from niceHash and alikes) and on-off mining like in merged mining and multi pools when miners jump from this coin to that one as for low hashrate altcoins.

2- The difficulty algorithm used is somehow dependent on timestamp service from oracles, .., which is not considered a best practice in crypto literature although there are some prominent figures supporting it. Current status for bitcoin that uses network adjusted time and allows up to 2 hours re-adjustment of node local time is not challenged and is doing well.

For above reasons I'm afraid this idea won't get enough support for PoW coins like bitcoin or ethereum that are not subject to on-off mining or niceHash rental attacks. other than that, the idea definitively worth spending some time to read and to think about and it is what I'm going to do right now.

[monsterer2]

It should be obvious that you cannot solve the 51% attack problem.

Greater than 50% is the smallest amount required for a majority. If your selection rule doesn't follow the majority vote, the process has broken down completely.

This leads us to the natural conclusion that 50% adversary proof is the best you can ever hope for in the byzantine generals problem - it is the theoretical maximum.