On Mon, May 20, 2013 at 08:54:25PM -0700, Gregory Maxwell wrote: > One point that was only recently exposed to me is that replacement > combined with child-pays-for-parent creates a new kind of double spend > _defense_: If someone double spends a payment to an online key of > yours, you can instantly produce a child transaction that pays 100% of > the double spend to fees... so a double spender can hurt you but not > profit from it. (and if your side of the transaction is > potentially/partially reversible he will lose)...
You can do better than that actually: you can arrange the transaction such that the double-spender is hurt by asking them to pay an excess on top of the initial payment, and having that excess get returned to them in a subsequent transaction. Of course, that's trusting the merchant, but you're trusting the merchant to ship to a product anyway so... A really interesting example for this though would be applications where you are making a deposit. You credit the customer account immediately with half of the deposit amount, allowing them to immediately spend that portion for something transferable. (perhaps an alt-coin) If the customer tries to double-spend you burn half to fees, still leaving the other half to pay for what they did spend. If they don't double-spend, the rest of the balance becomes available after n confirmations. A BTC->alt-coin exchange could use this mechanism for instance, although it only works with widespread replace-by-fee adoption; blockchain.info's shared-send service is another application, as is SatoshiDice. (the failed bet tx can be the refund) What's nice here is even if the customer tries to pay a miner to do the dirty work, a short-term rational miner still has an incentive to screw over the customer by accepting the merchant's double-spend. Now the customer can promise the miner future business, but they've shown themselves to be dishonest... how much honor is there among thieves? -- 'peter'[:-1]@petertodd.org 00000000000000f31f5cd20f915e3edb8e3fceea49580235b984fea63f1f882c
signature.asc
Description: Digital signature
------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may
_______________________________________________ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
