Hello Monsterer2,
In the following example, say I had a majority of stake at block A. Then at B0, C0 all the way up to head block H0, I sell off my majority of stake, understanding that there is an upper limit on stake transfer.
A - B0 - C0 - D0 - H0
\ B1 - C1 - D1 - H1
Then, I create a double spend of my stake using the historical private keys, which I still own, thus sending it to myself in a fork continuing fork B1 - C1 - D1 that I create and approve myself (majority stakeholder).
This is not a 50% attack, because I don't own the value held in the private keys anymore, the cost for doing this is nothing.
Why doesn't the network just accept this fork as canon, given that its the same length (or longer if I chose) than the genuine fork?
Any single person owning (or colluding with) a quorum (majority) stake is a problem because that person (or colluders) can rewrite the chain as they choose. This situation is essentially the same as an adversary owning a quorum stake which is the limit of the protocol.
In another scenario, some stakeholders may only approve their own blocks in an attempt to tilt the winning chances in their own favor. This is a real possibility. A possible mechanism to deter such an "attack" is to simply "blacklist" such stakeholders temporarily. An honest stakeholder can tell within a few blocks with certainty if another stakeholder is not approving his/her valid blocks.
My question is, what does the stakeholder have to gain by approving anyone's blocks but his own? If he has an edge by not doing this, there is a very real problem.
My assumption, which could be wrong, is
1. Stakeholders will approve (through approval message) more than one blocks or risk blockchain failure or being blacklisted by other node members.
2. Stakeholders will try to rank more candidate blocks created by other higher stakeholders lower in order to gain advantage in block creation.
Of course, these are just assumptions and need to be proven in real life.
Perhaps some coins should be given for approving a winning block in order of their ranking of the block. I am open to suggestions here. In the meantime I will analyze the if incentivizing block approval does have the desired effect.
Thanks for pointing it out - this is exactly what I am looking for from this forum.
Shunsai