Blocktix : Decentralized Network for Event Hosting & Ticketing Using Ethereum’s Blockchain (deepd.tw)

Blocktix is a novel, decentralized platform for ticket distribution and event hosting. The platform operates via Ethereum’s smart contracts, which enable verification of authentic tickets rendering it almost impossible to counterfeit them.
Blocktix is aimed at providing a decentralized network for distribution and sales of tickets. Individuals as well as companies can buy and sell tickets via means of cryptographic…

Bitcoin

What is the best way to prevent replay attacks in the event of a bitcoin hard fork?

I originally thought it would be relatively simple to add replay attack protection (change something about how the tx hash is generated) in the event of a fork. But the BU folks mentioned that this would break SPV clients (including many mobile wallets). So it is not free to do that way, although still an option.

One solution we brainstormed, was using some coins that were only valid on one chain (for example newly mined coins) and adding 1 satoshi of “taint” to all generated transactions. This would work but is not perfect. For instance, newly mined coins can’t be spent for 100 blocks, so at a minimum it would cause economic nodes to have a delay in the event of a hard fork. It is also non-trivial for all wallet software to implement this (fair amount of work, especially at scale). There is also an operational challenge that you would have to rush to get these newly mined coins while the hard fork was happening, so you could not prepare in advance. It would be a messy for sure.

Another option would be to try and double spend some coins across the forked chains (get a transaction with some coins going to two different addresses mined across the two chains). These coins could then also be used for “taint”, but you wouldn’t have to wait the full 100 blocks. This is a little bit better, but still not perfect.

I suspect there is a better solution though. What are people’s thoughts?

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