My understanding is these instant confirmations are still recorded in the block chain and if they are a double-spends, they are not recorded in the block chain.
They might well be recorded in the blockchain, but what use is that to a merchant who accepted the deposit (at 0 confirms) and took irreversible action when the transaction was confirmed?
When an InstantX lock is achieved (takes a couple of seconds usually) and broadcasted (and the merchant will see in his wallet the tx got IX comfirmation), how do you propose to reverse that?
I don't see how it's impossible at all. If I own a majority of masternodes, I can do whatever I like with my quorums and it doesn't just result in a 'no quorum achieved' it can result in double spends at 0 confirmations. Like I said before, if the system is designed to wait until 1 block has passed (in order to observe the quorum results), then you might as well throw it all away and just use POW?
If you own a majority of masternodes why would you do something that undermines your wealth? The 1000 coin collateral is there for a reason and that is to have an incentive for the nodes to act in the best interest of the network.
I guess it is intended for low value casual payments like buying coffee. No exchanges accept it afaik.
Rather like accepting a transaction at 0 confirmations... except it gives merchants a false sense of greater security which is actually really bad in general.
Transaction locking is a concept where a client sends the network an intention to lock funds from a specific input to a specific output (or multiple of each). This is done by relaying an object consisting of a full transaction and the locking command. The user will sign a message using the input(s), and relay the message throughout the network.
Transaction Lock: (txlock, CTransaction, nBlockHeight, Signed Message)
Locking messages will propagate across the whole Darkcoin network and reach all clients. Once the lock has reached everyone, a set of deterministically selected masternodes will form a consensus. Next, upon a successful consensus, a message will be broadcasted across the network and at this point all clients will respect the lock on the funds.