Would it be possible to use bitcoin pow as a replacement for captcha? It both blocks ddos and create an income through mining (client side) for the host.
No. In fact, using such a well-known proof of work function would defeat the purpose of using PoW. Instead of having something that's cheap for occasional users but expensive for spammers, you'd have something that's cheap for people who own mining ASICs and expensive for occasional users.
Hardware specialization breaks the economics behind a CAPTCHA. To fight that you need to use a PoW that hasn't been ASIC'd yet, and be willing to change PoW functions at the drop of a hat. PoW functions that stress memory or cache are also helpful here, though you run the risk of browsers flagging you as a cryptominer (which is technically correct, even if economically wrong).
> cheap for people who own mining ASICs and expensive for occasional users.
Seems like it should be the same cost (barring the friction of having a wallet, etc.) for both sets of people since Bitcoin is just a commodity and the value is the same to everyone, miner or not.
For example, a miner should value some fraction of a BTC the same way anyone else does, since they can sell or buy it at the same price a normal user can. The fact that they can profitably mine BTC just means they have a profitable business on the side, it doesn’t mean they should prefer to pay for services (or emails) in BTC.
It wouldn't create any income due to the electricity costs associated with mining, unless the users start buying ASICs. Also the most straightforward way of implementing this would be by having the user spending the token they generated in a transaction to prove their work, which would nullify their income. Maybe there is some workaround by monitoring the blockchain and seeing if a certain user generated some tokens at a certain time, but would it be worth the extra energy required due to the use of bitcoin' PoW? I think no.
kmeisthax|2 years ago
Hardware specialization breaks the economics behind a CAPTCHA. To fight that you need to use a PoW that hasn't been ASIC'd yet, and be willing to change PoW functions at the drop of a hat. PoW functions that stress memory or cache are also helpful here, though you run the risk of browsers flagging you as a cryptominer (which is technically correct, even if economically wrong).
smallnamespace|2 years ago
Seems like it should be the same cost (barring the friction of having a wallet, etc.) for both sets of people since Bitcoin is just a commodity and the value is the same to everyone, miner or not.
For example, a miner should value some fraction of a BTC the same way anyone else does, since they can sell or buy it at the same price a normal user can. The fact that they can profitably mine BTC just means they have a profitable business on the side, it doesn’t mean they should prefer to pay for services (or emails) in BTC.
GTP|2 years ago