A very naif bitcoin client that can be used using QR-codes for sending a bunch of satoshis. We'd expect to write few lines of code, keeping lots of logic in the hand of good javascript libraries.
The client should only broadcast the transaction to the network, course.
Development should be very git-oriented, using branches and pull-requests that has to be voted up by all the active members. Discussion happens on github issue tracker. Put there any code snippets, ideas, references you find useful. :)
Bitcoin, Javascript, bitcoin.js, bower, karmaQUnit, tweetnacl.js, jshint [, ...]
Every week, Alice's grandmother sends Alice 1 satoshi to address A using some crazy crypto software that Alice has no clue on how to use it.
She has (thanks to her grandmother) a paper wallet where both the address A and the private key key(A) are printed as QR codes.
Assume we're using some magic library for decoding QR codes
var qr = new QrCode();
qr.callback = function (res) { return res; };
var fromaddress = qr.decode(<DataURL of the QR for Alice's address>);
var key = qr.decode(<DataURL of the QR for the private key>);
(using dataURLs we can easily handle blobs).
Alice is meant to send 5 satoshis to Bob. She has only the QR code that contains the Bitcoin address of Bob.
Then, she decodes Bob's QR code too
var toaddress = qr.decode(<DataURL of the QR for Bob's address>)
(Bob owns a KFC franchise, and for 5 satoshis he gives you a pair of nasty chicken wings).
She queries the blockchain such to retrieve a list of hashes relative to unspent transactions using its address A.
She creates a Bitcoin transaction putting together as input her unspent transactions until they sum up to the 5 satoshis needed
using the txhints as a hint for a createTx({}) function that's just some sugar on top of BitcoinJS's bitcoin.Transaction(),
using as output both Bob's address and her address A to have her change back (if any).
She signs the transaction scanning her private key key(A) from the paper wallet.
She broadcasts the transaction to the Bitcoin network.
// Send a POST request to https://blockchain.info/pushtx
// where the tx parameter is set to tx.toHex()
Note that it's very likely this last HTTP request won't be sent due to the same-origin-policy protection. That shouln't be a problem, assuming we can grant enough privileges from the browser, e.g. packaging this app as a firefoxos one.
She waits 10 minutes, then transaction is confirmed and she bites her chicken wings. It would be nice to query the blockchain again after 10 minutes to check if some errors occurred.
EDIT: for the record, sending less than 5430 satoshis is not possibile.
Course, we would be very glad if you think this project is worth something and if you want to give us some help: any kind of help is appreciated.
We lack a UI, so even reporting bugs would be difficult if you're not a developer.
For those who want to contribute to the codebase, you should setup a development environment. You can use the script pushed on Github (check what it does before running!!)
$ curl -L https://raw.githubusercontent.com/NAGTeam/btclient/master/setupenv_Btclient.sh | sh
then setup a HTTP server using as the root directory the cloned repository.
You can use the python2 module
$ cd btclient
$ python2 -m SimpleHTTPServer
Now, hack on the project! :)
https://www.youtube.com/watch?v=3L4YrGaR8E4