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Really interesting! How efficiently does a web browser compute the PoW? I'm concerned that a bot would use an efficient GPU implementation while real users woul

Really interesting! How efficiently does a web browser compute the PoW? I'm concerned that a bot would use an efficient GPU implementation while real users would run an inefficient JS/webcrypto version.

jchw 3y ago
I tried to implement PoW in browser for the same concept. I think it's probably at least marginally useful, but practically you're limited by WebCrypto I think, which outperformed anything I could find in pure JS or WASM. The disadvantage of WebCrypto is that there's a limited set of algorithms you can use and also, understandably, calculating hashes is async, so if you want a lot of rounds, you'll spend a lot of time jumping in and out of the event loop. It's still probably a useful speed bump or price increase for expensive operations: what might cost a few seconds on a typical phone or desktop is probably at least enough to act as a speed bump for attackers to perform it quickly (especially combined with other measures like throttling and progressively increasing PoW difficulty for an IP.) Maybe WebGPU could change this, but I'm weary of relying on all users having a fast GPU enabled in their browser just for this use case. Though thinking about it, I wonder if there is a hybrid: start with a difficulty that's just a few seconds for CPU/WebCrypto and ramp up quickly, but also support WebGPU where possible so that web users on abusive connections may still succeed? I am not sure though, I guess this depends on the feasibility of using WebGPU and etc.
emporas 3y ago
Requiring every user to compute it's own PoW is a terrible idea. It defeats the whole purpose. One's person expensive computation is another person's almost free computation. I commented in the past about it: "At first glance, yes, we can create intentionally expensive computations without relying on a blockchain, that would serve the same purpose. In reality we cannot. Special computer hardware (ASICs) could generate much cheaper PoW annotations than general purpose computers, and sell it to spammers. Blockchain economic incentives ensure that ASICs will be used by the miners first and foremost." https://news.ycombinator.com/item?id=33533389 https://news.ycombinator.com/item?id=33533389
- comex 3y ago
  > Blockchain economic incentives ensure that ASICs will be used by the miners first and foremost. So instead, what, you want people to buy BTC and send small amounts of it to websites? Problem is, given varying income levels across society and across the world, one person's expensive micropayment is another person's almost free micropayment.
  - emporas 3y ago
    In a comment down below, i made it clear i was not referring to BTC. In the internet there is no centralized registry of naming projects. There are currently three projects in which the communities call themselves bitcoin. Any one of the other two bitcoins support much smaller microtransactions than BTC. Very true, that micropayments could vary on their relative cheapness across the global population. Let's put a number, is 0.01 cent affordable by most people on the planet, for every http request?
    - elcomet 3y ago
      So maybe you should link to the one you are referring to, if there are three projects with the same name.
      - emporas 3y ago
        I am talking about Bitcoin BSV. If the purpose of blockchain was solely to provide PoW, then there could exist a lot of blockchains, a thousand maybe. Economic incentives ensure that the most inefficient of blockchains will be put out of the market. So some of them, like btc will soon be put out of the market, because speed and microtransactions is the two factors every blockchain competes on. https://www.binance.com/en/price/bitcoin-sv https://www.binance.com/en/price/bitcoin-sv
        8organicbits 3y ago
        > This coin is not listed on Binance for trade and service. An obscure coin my users cannot purchase through major exchanges is a really poor solution. Sorry, that makes no sense.

jchw 3y ago

I tried to implement PoW in browser for the same concept. I think it's probably at least marginally useful, but practically you're limited by WebCrypto I think, which outperformed anything I could find in pure JS or WASM. The disadvantage of WebCrypto is that there's a limited set of algorithms you can use and also, understandably, calculating hashes is async, so if you want a lot of rounds, you'll spend a lot of time jumping in and out of the event loop. It's still probably a useful speed bump or price increase for expensive operations: what might cost a few seconds on a typical phone or desktop is probably at least enough to act as a speed bump for attackers to perform it quickly (especially combined with other measures like throttling and progressively increasing PoW difficulty for an IP.) Maybe WebGPU could change this, but I'm weary of relying on all users having a fast GPU enabled in their browser just for this use case. Though thinking about it, I wonder if there is a hybrid: start with a difficulty that's just a few seconds for CPU/WebCrypto and ramp up quickly, but also support WebGPU where possible so that web users on abusive connections may still succeed? I am not sure though, I guess this depends on the feasibility of using WebGPU and etc.

emporas 3y ago

Requiring every user to compute it's own PoW is a terrible idea. It defeats the whole purpose. One's person expensive computation is another person's almost free computation. I commented in the past about it: "At first glance, yes, we can create intentionally expensive computations without relying on a blockchain, that would serve the same purpose. In reality we cannot. Special computer hardware (ASICs) could generate much cheaper PoW annotations than general purpose computers, and sell it to spammers. Blockchain economic incentives ensure that ASICs will be used by the miners first and foremost." https://news.ycombinator.com/item?id=33533389 https://news.ycombinator.com/item?id=33533389

comex 3y ago
> Blockchain economic incentives ensure that ASICs will be used by the miners first and foremost. So instead, what, you want people to buy BTC and send small amounts of it to websites? Problem is, given varying income levels across society and across the world, one person's expensive micropayment is another person's almost free micropayment.
- emporas 3y ago
  In a comment down below, i made it clear i was not referring to BTC. In the internet there is no centralized registry of naming projects. There are currently three projects in which the communities call themselves bitcoin. Any one of the other two bitcoins support much smaller microtransactions than BTC. Very true, that micropayments could vary on their relative cheapness across the global population. Let's put a number, is 0.01 cent affordable by most people on the planet, for every http request?
  - elcomet 3y ago
    So maybe you should link to the one you are referring to, if there are three projects with the same name.
    - emporas 3y ago
      I am talking about Bitcoin BSV. If the purpose of blockchain was solely to provide PoW, then there could exist a lot of blockchains, a thousand maybe. Economic incentives ensure that the most inefficient of blockchains will be put out of the market. So some of them, like btc will soon be put out of the market, because speed and microtransactions is the two factors every blockchain competes on. https://www.binance.com/en/price/bitcoin-sv https://www.binance.com/en/price/bitcoin-sv
      - 8organicbits 3y ago
        > This coin is not listed on Binance for trade and service. An obscure coin my users cannot purchase through major exchanges is a really poor solution. Sorry, that makes no sense.