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Currently, if you control 51% of the network hashing power, then you can force the longest branch of the blockchain to contain anything you want. However, anoth
by teraflop 13y ago
Currently, if you control 51% of the network hashing power, then you can force the longest branch of the blockchain to contain anything you want. However, another client's view of the blockchain will reflect the longest legal branch that it sees, by its own definition of legality. Any miners that don't consider it to be legal will start their own fork. (This is exactly what happened, briefly, with the LevelDB fiasco some time ago.)
I think you'd have to do this in two stages. First, create a version of the client that accepts a particular exceptional transaction if it appears in the blockchain. Wait for a supermajority of clients to switch to the new version; once the fraction gets high enough, everyone else will be forced to upgrade too, or risk being on the losing side of a schism. Then it would be safe for miners to actually execute the transaction.
- VMG 13y agoYou'd still have to convince most users and stakeholders of Bitcoin (merchants, exchanges, etc) to update to the new version in order to avoid a Blockchain fork, where both sides of the fork are likely to lose and the currency is destroyed. As the owner of 51% hashing power, you can try to convince the network to update by holding it hostage and threatening a DOS attack by mining without verifying transactions, but I don't think that would be economical either.
- tlrobinson 13y agoI don't understand the "mining without verifying transactions" part. You mean mining empty blocks?
- VMG 13y agoyes, this even happens now (very infrequently)