Show HN: rePOWCHA – CAPTCHA that stops Humans, powered by crypto | Hacker News Reader

Show HN: rePOWCHA – CAPTCHA that stops Humans, powered by crypto

repowcha.com

9 pointsrepartix8 comments

> - if there was abuse, you earn 99% of the refund amount and rePOWCHA earns 1%

> - if there was no abuse, you earn 0.75% of the refund amount and rePOWCHA earns 0.25%

> - the minimum earned amount is the cryptocurrency's network fee

I'm a bit confused by the fees here. Seems like avg transaction fee right now is .05 USD. What's the practical cost of this? Seems rather expensive.

There's no "avg transaction fee". The transaction fee is derived from the deposit amount, and it's you who chooses the deposit amount (from ~$0.01 to $500) when creating a new rePOWCHA. The deposit amount isn't a fixed $5 that you see on the front page.

What you may be asking is, why is there any fee if there was no abuse. Maybe there shouldn't be. I'm open to removing it.

The practical cost right now is small, since the service just started 2 days ago and has few users. I don't know if the service will be sustainable at scale if there's no abuse. Maybe there will be enough abuse that the service will be sustainable from the 1% "abuse" fee. There would have to be some way for the service to pay for itself.

As a user, a bigger issue may be that the mere thought the user won't have 100% of their deposit refunded may deter them from using the service. I'm more inclined to remove the "no abuse" fee for this reason.

On the other hand, as a web app that integrates rePOWCHA and with a large userbase, the web app may want to monetize this user interaction.

So I don't know what will work best. There's probably a balance there.

Since the fee seemed rather expensive to you, what fee structure would you suggest for the "no abuse" case?

Thanks for detailed reply! I didn't mean to imply that "it's expensive to me" just wondering about the general economics of this exchange because crypto payments are notorious for awkward fee calculations.

I consider myself quite competent on this crypto stuff... Yet it would still take me substantial effort to find some Litecoins... I'd have to find an exchange, set up a wallet, etc.

Why not just use bitcoin or lightning channels?

And if you want this service to really succeed, you need a place to just paste a credit card and have it do a preauth...

How did you find your Bitcoins? Just as you setup a wallet for Bitcoin, you can can setup a wallet for Litecoin.

An easy wallet to try is Coinomi. It's an app that installs on your phone and has a built-in exchange. Here are some links to install it:

Coinomi on iOS https://apps.apple.com/us/app/coinomi-wallet/id1333588809

Coinomi on Android https://play.google.com/store/apps/details?id=com.coinomi.wa...

If you're looking for a Litecoin wallet for the desktop, try Electrum-LTC https://electrum-ltc.org/. After you create a wallet, you can exchange some Bitcoins for Litecoins through https://swapspace.co/

I don't know much about lightning network channels. I'll look into it. Thanks!

On using a credit card, I built something similar that could take a credit card through Stripe. The problem there is people are a bit reluctant to type in their credit card number, in case the number gets stolen. Crypto is safer for this because the private key stays with the user on their phone or desktop wallet. Also, pasting the credit card, expiration, and your name takes longer than scanning a QR code with your phone.

Not sure why this was flagged dead, but it seems somewhat interesting, the https://repowcha.com/how_it_works page is at least thought provoking.

Is it more for showing skin in the game? What are the usecases this could be appropriate?

Yes, the key idea is to show skin in the game. Check out some usecases in https://repowcha.com/use_cases. It's nothing fancy, just simple tech that might work better.

Ordinary CAPTCHA tries to tell humans and bots apart, to stop bots from abusing a service. rePOWCHA does something different: it tries to tell if humans have good intentions using the oldest trick in the book. It asks the user to deposit some crypto as collateral. Honest users who don't abuse the service get their deposit refunded, and spammers don't.

Another difference is that it's not rePOWCHA who decides who gets back their deposit. It's the customer (you) who decides. Think of rePOWCHA as giving control back to humans instead of hoarding it for the bots. It's also free and you make money from the fees.

The big problem I see with CAPTCHA is that verifying if someone is human isn't enough to guarantee they won't abuse your service, like what happened with repl.it a couple of months back (https://replit.canny.io/feedback/p/add-captcha-to-new-post). The key insight is to make spam expensive enough that it's unprofitable, instead of merely less likely.

I want a similar way to stop spam for email. Crypto works better than a credit card for this since you can find the sender's address in the blockchain to refund their money, and also to reward them for sending good emails.

And then there's the world of online forums. Don't like getting downvoted on HN? Threads getting out of hand? Built a new online forum that requires paying to post, reply, and vote.

You can pay customer support for responding well or responding fast.

You can send rePOWCHA links to friends to pay you back lunch money.

Proof-of-work for the web is inevitable. This is a new mechanism.

I'll be hanging around in the comments this morning if you have questions or feedback. Feel free to reach out directly at repowcha@protonmail.com

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