93

In this answer, I will go through the steps necessary to redeem the second output of the transaction listed above. The answer will be limited to redeeming an output of the particular type present in this transaction (an output which requires providing a new transaction signed with a private key whose corresponding public key hashes to the hash in the script ...


45

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 ...


23

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 ...


17

I am basically doing the same thing for bitcoinmonitor.net. I have a database of addresses to monitor and get notifications from bitcoind for any incoming transaction. I maintain a patchset for bitcoind which allows setting an url which will be called with any incoming unconfirmed transaction, including transaction details in a json object. Also for any new ...


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 characters excluded in Base58 are 0OIl. oiL are allowed, making these two valid addresses. It is impossible to send to an invalid address, as Bitcoin transaction scripts actually include raw 160-bit hashes (which by definition have a one-to-one correspondence with valid addresses), not addresses. Bitcoin clients will simply refuse to do anything if an ...


11

None. It's impossible to send bitcoins to an invalid address. Those addresses are valid, though they might not be owned by anyone. Look at pszBase58 more carefully: 'o', 'i', and 'L' are allowed. The first few posts in that forum thread are wrong. The network doesn't know anything about Bitcoin addresses. At the network level, you never send bitcoins to an ...


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.


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 ...


10

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 ...


10

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 ...


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

An orphan transaction is a transaction that consumes a coin whose creating transaction is not known to your client. This has nothing to do with orphan blocks (which are blocks whose parent block is not known, or according to another definition, blocks that are no longer part of the best chain). Orphan transactions are not part of a block (they cannot be ...


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

There is now the XChange library This is a pure Java library that has been released under the MIT license. It currently supports Mt Gox, but there are simple hooks to allow other exchanges such as Intersango and CryptoXChange to be supported. It is currently used by the MultiBit client.


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

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, ...


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