47

I know this question is old, but I stumbled upon it looking how to teach myself how multisig addresses work, and I imagine others will to. So I’m going to try to explain the typical flow for creating, adding bitcoins to, and eventually spending a multisig address. This explanation is aimed at beginners, so please excuse my lack of brevity. First off, some ...


27

Enable txindex=1 in your bitcoin.conf (You'll need to rebuild the database as the transaction index is normally not maintained, start using -reindex to do so), and use the getrawtransaction call to request information about any transaction (it won't work for the genesis block's coinbase transaction though, it's a special case). Note that this will only give ...


13

(disclaimer: I work on Bitcoin Core) As Luca already mentioned, you have to distinguish wallet implementations and the fully verifying nodes on the network. Because of how Satoshi wrote his code (a node and a wallet in the same program), the two are often confused, but this is considered a bad idea now. They can perfectly function independently. The ...


12

The basic elliptic curve operation is addition of points. The operation of applying this addition repeatedly is called the scalar multiplication of a point by an integer. The private key is the 'scalar', the point being multiplied is the 'Generator' point, the result is the public key. Scalar multiplication is basically repeated addition. Multiplying the ...


11

Chris Larsen has been publicly identified as CEO of OpenCoin, the company behind the new Ripple. The core developers have been publicly identified as Jed McCaleb, Arthur Britto, Stefan Thomas, and me (David Schwartz).


11

The reference implementation, Bitcoin Core, is written primarily in C++, with various resource files and scripts in other languages. Another implementation, mainly used in lightweight clients like MultiBit and Bitcoin Wallet (Android), is bitcoinj. It is written in Java.


11

To understand Bitcoin Core, the best resource is probably the source code itself: https://github.com/bitcoin/bitcoin To help understand what is going on in the code, try the developer documentation and the Princeton Bitcoin Book. Keep in mind that the code gets updated faster than the documentation, so the code should be your source of truth. Some ...


10

If scripts were Turing-complete, you could construct a fairly short script that took an extremely long time to run (a la the Busy Beaver) or contained an infinite loop. This would tend to result in a denial of service against everyone on the network, when they tried to verify the transaction. And there would be no general way to tell whether a script ...


9

I would recommend using Homebrew or MacPorts to manage this dependency. The Homebrew package is simply pcre or pcre++. brew install pcre pcre++ The MacPorts packages are pcre and pcrexx. sudo port install pcre pcrexx


8

part of https://github.com/mikegogulski/bitcoin-php/blob/master/src/bitcoin.inc private static $hexchars = "0123456789ABCDEF"; private static $base58chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"; public static function checkAddress($addr, $addressversion = "00") // hex byte { $addr = self::decodeBase58($addr); if (strlen($...


8

Creating a SatoshiDice-like game is rather easy. Below are the high level steps involved in making such a game. For each incoming transaction... Get the customer amount and payment address Call bitcoind getrawtransaction [The incoming transaction ID] 1. The 1 at the end will return the data in "verbose mode", which essentially the raw data in JSON ...


8

Check this: https://en.bitcoin.it/wiki/Testnet The testnet is an alternative Bitcoin block chain, to be used for testing. This allows application developers or bitcoin testers to experiment, without having to use real bitcoins or worrying about breaking the main bitcoin chain.


8

There are two Bitcoin softwares that should be differentiated: (i) the client software that everyone uses and (ii) the full Bitcoin node used by the miners. With regards to implementations, there are a variety of different clients. Just look at MultiBit, Electrum, Armory, Hive etc. Many are implemented using different programming languages and libraries. ...


8

In comparison to languages like Java or C++, Python has several advantages for coding bitcoin projects: Simplified rules of coding allows beginners and experienced alike to code and get results without getting bogged down in formatting etc Shell allows on the fly calculations Python code is easily read and as such can be edited to suit Python can be ...


8

I just published a book about it. It's called "Blockchain Programming in C#". If you're looking for tools written in C#, you should try NBitcoin. You can also find the project on GitHub. I've also written lots of articles about it: Intro: http://www.codeproject.com/Articles/768412/NBitcoin-The-most-complete-Bitcoin-port-Part-Crypt Stealth Payment, and ...


8

Tim S. pretty much covered it, but I wanted to 2 great resources which have been very helpful for myself and many others: Ken Shirriff's blog has a few Bitcoin mining related posts which use Python code to great effectiveness; whilst Bitcoin Mining The Hard Way is probably the most useful, there's also some novel use cases where Ken tries Bitcoin mining by ...


7

This gist, partially based on the answer by Runeks, shows how to transfer 0.01 bitcoins in Ruby. It fetches information from the previous transaction from Blockchain.info, so you just need to feed it your private key and address (the latter being redundant but useful for the demonstration). I added a lot of comments to explain the steps involved.


7

Testnet is designed to test Bitcoin software - including parts that have to do with finding blocks. As such, it should be easy for developers to generate testnet coins. Because of this, it will be easy to solo mine on a CPU to generate them, and you should not use anything heavier than that because you would ruin it for everyone else. It is also not ...


7

I have recently created a TestNet Faucet. It is available on http://tpfaucet.appspot.com/ I hope this remedies the situation To answer your question - while there is nothing stopping people from charging for TestNet coins, I think they should be freely available to anyone for testing. It lets newcomers get a feel for what Bitcoin is without risking their ...


7

This is all I could dig up from https://en.bitcoin.it/wiki/SatoshiDice SatoshiDice was the brand given the service initially created by BitcoinTalk forum user FireDuck before selling the system to another operator.


7

May be useful psp(python) example: <%psp import urllib2; import simplejson as json; j = json.loads(urllib2.urlopen("https://data.mtgox.com/api/2/BTCUSD/money/ticker").read()); %> <%=str(j["data"]["last"]["value"]) %> Or one command line: # /usr/bin/python -c 'import urllib2; import simplejson as json; j = json.loads(urllib2....


7

I was asked by Hasan Hasan, a junior developer, which of the following three books I'd recommend. Personally I think all three books are fantastic (I would recommend them all) but they do approach the topic from very different angles. Mastering Bitcoin (2nd edition, Andreas Antonopoulos) was the first technical Bitcoin book to be published. The 2nd edition ...


7

There is a Complete Guide on How to Create a New Alt Coin on Bitcoin Talk.


7

A great way to start programming blockchain-based apps in C# is BitcoinLib, which also comes with a test console app that demonstrates how you can build a blockchain app in a few lines of code. Repo: https://github.com/GeorgeKimionis/BitcoinLib Some of its features are: Fully compatible and up-to-date with Bitcoin 0.9.3 RPC API. Design-by-contract, ...


7

I'm not sure that a guide as basic as you describe is even possible. It depends on what exactly you mean. Mining itself isn't too complicated to read and understand, but writing a start-to-end app that can be used for mining means writing a full node. That is very complicated. Writing a Bitcoin miner from start to end involves not only collecting ...


7

No, the number of full nodes is decoupled from capacity and fees. Transaction capacity is a function of transaction size and blocksize. Blocks occur roughly every 10 minutes and have a fixed size. Transactions also have a more or less fixed size, so capacity is currently not going to change unless either transactions get smaller (e.g. Schnorr signatures, ...


7

I think you are confusing some things here. A blockchain like Bitcoin, Ethereum, Ripple, or Hyperledger is a protocol in first place. And a protocol is agnostic to programming languages used. What you are relating to are reference implementations of the protocol. The Bitcoin protocol has the famous Bitcoin implementation (later Bitcoin Core) initially ...


6

Below extract should answer your question. public class ECKeyPair implements Key { private static final SecureRandom secureRandom = new SecureRandom (); private static final X9ECParameters curve = SECNamedCurves.getByName ("secp256k1"); private static final ECDomainParameters domain = new ECDomainParameters (curve.getCurve (), curve.getG (), ...


Only top voted, non community-wiki answers of a minimum length are eligible