Bitcoin : Time for OP_CHECKBLOCKATHEIGHT: Fork-neutral replay protection, and a really useful tool

Bitcoin : Time for OP_CHECKBLOCKATHEIGHT: Fork-neutral replay protection, and a really useful tool

Back during the block-size wars, when it looked like the miners might back a fork of BTC to raise the block size, developer and Christianity enthusiast /u/luke-jr proposed an opcode to called OP_CHECKBLOCKATHEIGHT. What this allows you to do is to add something to your transaction saying, “if the block at height X doesn’t have the hash xyz, make this transaction invalid”.

If this had been in place beforehand, it would have worked as replay protection in the ABC/SV fork, allowing you to transact in ABC safe in the knowledge that you’d still have your SV coins to sell when the exchanges start taking deposits. Even aside from contentious forks, it’s also potentially useful in protecting you against various network partitioning tricks; As a general rule, if the chain you’re transacting on doesn’t look the way you think it does, you’re going to have a bad day.

Luke isn’t a great friend to BCH, but this is a really good proposal for any version of Bitcoin. The great thing about using this for replay protection is that it doesn’t need anything extra done by the chain that forks. This is important because when a chain forks, they often have tactical reasons for not *wanting* to add replay protection, so if you leave it until then it may be too late.

Like it or not, economic forks are part of the governance model of crypto-currencies. Some disruption is inevitable, but chains that want to be useful should do what they can to mitigate the damage and remove any reason to stop making useful transactions when it happens.

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Author: edmundedgar

Score: 15

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