>One way to sidestep this: every few minutes, post the longest hash to some distributed medium that can't be edited, like Twitter. Then the threat model moves to "do we trust the person with the keys to this twitter account?"
The XRPL does this by broadcasting. Every node tells everyone what they think is right, therefore everyone can see who lies and more importantly no one can see who you listen too. Its hard to trick me if you dont even know whom I listen too.
And you cant test it because once you lie to me you lie to everyone and that the last time anyone listened to you.
The "zero trust" thing is an illusion. All decentral systems trust that the majority of something does "the right thing".
Some system use the majority of hashpower other use other metrics and some lets you pick and include or exclude participants.
BTC for example doesn't give you any options you simply trust that from 100% hashpower more than 50% is controlled by honest people. Its not zero trust its more like zero choice trust.
Yes, one thing is unavoidable, you have to assume that the majority is honest else the system simply can not work.
Identifying the majority is however optional. BTC for example does not. You pick the longest chain you can find at a given time. You assume the majority saw the same as the longest. If a longer shows up you switch and again you assume the majority saw that too and switched swell.
Other systems like the XRPL dont assume, every node defines from whom they want a majority.
If 99% of them made a Tx final then there is no way that at a later point in time this final state can be changed because 1% can not ever reach a majority. The only thing that could happen is that the network forks and different parts of the network reach majority on different states. This problem is solved by raising the majority needed to 80% rather than >50% and on top of that is is further reduced by intentionally overlapping the nodes who are defined by each node.
Essentially you need many nodes who listen to each other both ways. So I choose your node to be part of my nodes that must reach majority and you list my node.
If you have 10 nodes all listen to the other 9 and require that form the other 9 80% agree then there is no way the network can ever fork. No 2 different states could ever reach 80%, its just not possible.
Now these 10 nodes are publicly known so if you operate a node you have to pick from these nodes the one you want but you must make sure that your node can not reach a majority without them. So you could pick all 10 and then add for example 5 others. Your node can hen also not fork because the 5 alone can never reach an 80% majority. and so on and on. every new node must have ~80% overlap to prevent forking.
And all of that is super simple because the nodes are public and use public key encryption to identify themself.
> The only thing that could happen is that the network forks and different parts of the network reach majority on different states.
That's the main thing that Bitcoin solved, how to resolve this exact situation. You can't just ignore this problem and claim to have a similarly resilient design.
> This problem is solved by raising the majority needed to 80% rather than >50% and on top of that is is further reduced by intentionally overlapping the nodes who are defined by each node.
The first part just makes it slightly more expensive to do a sybil attack. The second part relies on someone deciding what the overlapping nodes are, now you have to trust them.
> If you have 10 nodes all listen to the other 9 and require that form the other 9 80% agree then there is no way the network can ever fork.
And now you have a network that can't grow beyond 10 nodes, and if more than 10 show up you need to somehow choose the ones that are honest. Or someone needs to decide which nodes get to be the "special 10".
> Now these 10 nodes are publicly known
And chosen by whom? Can you trust the entity that chooses them? Can you trust them not to be hacked and share malicious nodes instead?
The XRPL does this by broadcasting. Every node tells everyone what they think is right, therefore everyone can see who lies and more importantly no one can see who you listen too. Its hard to trick me if you dont even know whom I listen too. And you cant test it because once you lie to me you lie to everyone and that the last time anyone listened to you.
The "zero trust" thing is an illusion. All decentral systems trust that the majority of something does "the right thing".
Some system use the majority of hashpower other use other metrics and some lets you pick and include or exclude participants. BTC for example doesn't give you any options you simply trust that from 100% hashpower more than 50% is controlled by honest people. Its not zero trust its more like zero choice trust.