[THIS FIRST POST WILL BE EDITED CONTINOUSLY AS THE PROJECT DEVELOPS]​

The goal of the Ka-ching project is to make NFC payments with Bitcoin Cash (BCH) as convenient as possible with reasonable security.Ka-ching is an open source project.You pay for your goods by holding your ring against the NFC POS terminal in a store.You have now paid with Bitcoin Cash.It’s all about making a great UX. Better than contactless creditcards without PIN, or mobile payments.A contactless creditcard has to be dug out of your pocket or handbag and put back after use. You have to keep it in a geeky, shielded wallet if you want to protect yourself from digital pickpockets. You can not choose the limits for how much you can pay without a PIN code.Phones are equally clumsy. You have to keep them charged, dig them out of a pocket or handbag and put them back after use.With a Ka-ching rubber bracelet or ring, you can go straight from a swim in the ocean to the beach bar and buy a beer.Bitcoin experts are trained in thinking about extreme security. Therefore, it can be difficult to start thinking about reasonable security. The Ka-ching will have a button that needs to be pushed during the transaction. This is to prevent digital pickpockets to steal your funds. In the case of a ring, the button will probably be on the back side of the ring, letting you hold it in with your thumb. Or the button is under the flexible NFC antenna, so you can push it against a surface to activate.Ka-ching is not push. It's pull. Or semi-pull? Hard to define. But you hand over your total funds to the merchant and ask him to take as much as you have agreed on. Some trust is involved.But what if someone steal your ring? Well, thieves steal gold rings. And phones. And creditcards. And cash. But people still use them. Maybe you take off jewelry or an expensive watch in a rough neighbourhood at night, or keep your handbag closer in a bar. Key words: Reasonable security.You are not supposed to have a lot of money on your Ka-ching. Just enough for everyday shopping. And if you pair your Ka-ching with your phone, you can auto-refund at a level of your choice.Ka-ching is inspired by Peter Rizun’s SigSafe project. And it can be used the same way as SigSafe. You can use the Ka-ching to have a multisig vault on your phone. And you may re-fund your Ka-ching from that vault. The two concepts work great together in the same phone app!A Ka-ching device will be able to send and receive money straight out of the box. But it will work even better if you pair it with your phone. After pairing, you will get notifications on your phone about how much money the merchant took from you. And if you lose your phone, your Ka-ching or both, you can recover everything (vault included) with a twelve word seed backup.Ka-ching is a tiny NFC antenna and micro controller. No need for battery! Waterproof! Cheap! It’s open source, so everyone can make them. And designers can get creative and put them in jewelry, bracelets, rings, inside jacket sleeves, at the end of a zinger, on handbag straps, inside your gloves, on headset cables, you name it!A Ka-ching device is able to do all the things mentioned and more with just a few simple rules:- Send it’s public key or address or xpub key. (TBD. Input from you, please!)- Sign transactions given to it with it’s stored private keys and return the signed transaction.- Overwrite private keys with new private keys. (When you “pair” it with your phone, you will generate new keys from the seed, transfer funds to a new address and overwrite the old keys with new.)For all this to work, we need to specify the Ka-ching protocol and convince POS terminal makers like Ingenico all over the world to add some new software to their existing hardware.I will lead this project, but I will not be the developer, as I haven’t coded in many years.Make some noise in the comments below if you think this is a great idea or a security nightmare.Let’s kick some butt in the payments space!Background: @Peter R 's video about SigSafe:How small an NFC chip is today (video down on the page).