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Hands-on demo of Sia's decentralized storage tech
Hosting a mirror of the English Wikipedia on Skynet for $3/month
The IPFS Wikipedia mirror is from 2017; an up-to-date snapshot is now on Skynet
Wikipedia mirror on Skynet (Kiwix-based)
What is Ethereum, 2nd gen. cryptocurrency, good for? – a visual example
What is Ethereum, the 2nd gen. cryptocurrency, good for? – a visual example
Ethereumpyramid.com – visualizing the state of an Ethereum pyramid contract
Offline Bitcoin wallet completing a payment via NFC and Bluetooth [video]
Bitcoin payment terminal combines NFC and Bluetooth for offline payments
How Hive’s New Web Wallet Attacks Bitcoin Adoption Roadblocks
When I started on this project, Mt.Gox was pretty much the only choice, because of the large market share (> 80% at the time) and the necessary volume and small enough market spread. Their withdrawal delays are annoying, that's true. It does not affect me directly, since it's only Bitcoin in and Bitcoin out for me, where so far Mt.Gox had pretty much never delays. But it does distort the market price, which means you get a great rate when you fund your Bridgewalker account (because BTC is overvalued on Mt.Gox) and get a bad rate when you spend it (again, because BTC is overvalued on Mt.Gox) - so in the end it kind of zeroes out for you as a user, but it's still confusing for the user, why you have this offset.
There aren't many alternatives though. Bitstamp could be one, but I'm worried that they still might run into regulatory issues down the line. Also none of the other exchanges offer real-time streaming updates about changes to the order book, like Mt.Gox does, which is very useful to keep track of the market. Kraken could be an interesting alternative to Mt.Gox, since they seem to run a solid operation. If they add such a streaming API with real-time updates about the order book and maybe get some more volume, then I would consider switching the backend over.
Or someone else does it first - it's open source now, after all! ;-)
Or maybe you could hedge the whole thing just with some financial swap construction, but I haven't looked into that too much and it's not my area of expertise. I would be interested to find out how much something like that would cost in terms of overhead/fees and who would be a partner to provide such financial services for Bitcoin. If you have some input regarding this, feel free to contact me - my email address is on the Bridgewalker website.
If you happen, for example, to stand in front of a Bitcoin ATM, you can use that to turn fiat that you have in the form of cash into fiat that you have in your Bridgewalker account (by buying Bitcoin from the ATM and sending it to your Bridgewalker address), which you can then later spend wherever it says "Bitcoin accepted here".
A lot of exchanging back and forth for sure, but basically the idea of "Bitcoin only as tranfer mechanism" applied at every step. It's also just a technical prototype. In practice it might make sense to cut some of those exchange fees by having a more direct way to fund your account, at the cost of only being available in certain markets/countries. For this prototype I went with the easiest solution: only Bitcoin in, and Bitcoin out.
So: Bitcoin as transaction mechanism, Euro as store of value.
My acquired Bitcoin startup Bridgewalker is now open source
Video of a Bitcoin point of sale solution using NFC for contactless payment
Using Bitcoin, NFC and Bluetooth to make a mobile euro payment in 15 seconds
Bridgewalker: an exchange rate adjusted Bitcoin wallet (now with short demo)
Bridgewalker: an exchange rate adjusted Bitcoin wallet
Bitcoin mobile checkout solution from Bit-Pay [video]
Bitcoin: Point of sale system - video of demo payment
Demonstration of a simple Bitcoin point of sale solution
The problem was, that transactions can have "change". So by sending 1 BTC, the client did in fact send 1 BTC to one address and the remaining 8999 BTC to a a newly generated address which is automatically added to the wallet. Since the backup was before this transaction, the backup didn't include the private key to the change address and 8999 BTC were lost.
A really unfortunate incident, as the person simply didn't know this technical detail. It prompted some upgrades to the client, which now generates addresses in advance and stores them in the wallet. When new addresses are needed, the ones from this pool are used first. With a recent client this accident would not have happened. It's still important to know though, that after _sending_ Bitcoins, a wallet might potentially include new private keys that are not in an old backup (if the pool has been completely used up since the last backup).
By the way: All this happened in August 2010, so this wasn't $81,000 at the time.
On the other hand, most pools have moved to include several recipients into a single transaction, so if it is a pool, it's somewhat "outdated".