An increasing number of projects are solving the problem of how to convert BTC into a 1:1 pegged asset on another blockchain and back: the "two-way peg". Each has its own approach. This blog post will look at several of the different approaches and compare them. Keep in mind that this is a fast-moving space…
not all of the examples in my post rely on a single centralized organization! in several cases, it's a federation of organizations. and in the case of Drivechain, it's incentives (or miners/users, depending on your viewpoint) that secure the peg.
Drivechains have far lower security than the mining model, despite using the same set of nodes. For one, even 51% miners of Bitcoin cannot reassign the value of your deeply-confirmed HODLings to themselves, whereas a 51% miner coalition can reassign the entire backing funds of a Drivechain sidechain to themselves (by making an invalid withdrawal proposal and censoring attempts at downvoting it).
A miner coalition can be coordinated by, instead of having the withdrawal proposal pay out directly to some individual miner, be paid out to a form of HTLC that pays out to a "mastermind" thief if it reveals a hash (or, on timelock, can be claimed by any miner), who then coordinates with miners by identifying their public keys (easily done by looking at coinbases) and initially creating HTLCs (before the attack starts) that pay out to miners they are inviting to attack the sidechain. If the theft pushes through then the mastermind gets the withdrawal proposal output that requires them to reveal the hash (if the mastermind does not, the timelock will let it be taken by any miner, so the mastermind has an incentive to reveal the hash quickly), and then the pre-paid HTLCs they used as enticement can be unilaterally claimed by the miners invited, whether they participated in the theft or not, as their "cut" of the stolen goods. If the theft fails, then the mastermind recovers the HTLCs they paid out to miners after the timelock.
Users cannot vote on drivechain, thus they cannot secure it. Only miners can, and miners are not so anonymous they cannot be identified and tempted with the above scheme. The original SPV-proofs sidechains proposed by Blockstream would have been user-validated by all Bitcoin fullnodes, but it would still have required independent hashpower for the sidechain, which is impractical given that hashpower can be redirected to attack low-hashpower sidechains and rewrite a good amount of history, which means that its security would only be slightly better than Drivechains, as well as diverting hashpower from securing Bitcoin to attacking sidechains.
> Users cannot vote on drivechain, thus they cannot secure it.
This is not entirely true, as users could organize a UASF to block a malicious withdrawal transaction. Yes, it would require enough miners to go along with the UASF to prevent a chain split, but if there's enough value at stake I think it could be organized and it would be users leading the charge. The very possibility of this threat makes it less likely that the threat will ever need to be used. (Similar to the "nuclear" option of changing the PoW algo if miners threaten bitcoin - the very fact that this option is available makes miners less likely to do anything that would warrant it.)
I suppose that is correct
However, do note that *mainchain* users have to do this UASF. People who do not particularly care about any particular sidechain would just shrug; it would be just another exchange hack, notyourkeys notyourcoins. It's not like it's an existential threat like being unable to use higher-layer systems.
Sure. And if people don't like that security model, they don't have to use drivechains. Same how if people don't like the Lightning Network security model they don't have to use Lightning. Let users decide their own risk/benefit tradeoffs.