This post is a basic introduction to the OP_RETURN Op Code , which can be used to store data in the Bitcoin Blockchain.Doing this requires an intermediate understanding of the Bitcoin protocol and some familiarity with the Ruby programming language Bitcoin is primarily known as a digital currency; however, it is much more than just a type of ‘digital money’.Bitcoin transactions can also be used to store small amounts of extra data in the blockchain - allowing developers to build distributed applications and protocols on top of Bitcoin, such as Counterparty and Mastercoin.These Bitcoin 2.0 protocols have the potential to enable decentralized asset exchange, securities issuance, betting and contract settlements - all on the Blockchain.Storing extra data in the Bitcoin Blockchain is controversial.Some people see it as ‘dirtying’ the blockchain, but it is part of the protocol nonetheless and allows developers to build interesting technologies.We will walk through how to create a bitcoin transaction that includes an extra “secret message”.

This message will then be stored in the blockchain when we propagate the transaction.To follow along you must have some familiarity with Bitcoin and the Ruby programming language.You must also own some bitcoin.We will use the Electrum Bitcoin wallet and the bitcoin-ruby library to generate this transaction.WARNING: Do not do this if you hold significant funds in your Electrum wallet.This is for fun/development only.If you make a mistake you can lose your wallet funds.Let’s start by opening up the Electrum Console and getting a list of our unspent transaction outputs: Here is an example of one of my unspent outputs (I changed some of the values for privacy).All we need from this is the prevout_hash and prevout_n of the output we want to spend.You should only use an output with a small “value” amount.This is the output we will use as the input to our new transaction.In order for this transaction to be valid, we need to sign it with the private key of the address of the output we are using (1AjbRh…) to prove that we own it.

In order to find this key, type: The resulting array shows the private key.Anybody with this string can spend the bitcoin at the corresponding address.We also need the JSON representation of the transaction with hash prevout_hash.Paste this JSON data in a file named tx.json.Here is an example.Now we have all of the information we need to generate the transaction.We will use the bitcoin-ruby gem to do this.When run, this code will return the JSON and hex versions of our signed transactions: We’ve done it!bitcoin exchange in egyptYou can see our secret message encoded after OP_RETURN in the second output.ethereum streamOP_RETURN is an “Op Code” in the Bitcoin scripting language that tells the script interpreter to ignore everything after it.bitcoin 4500

You are allowed to store up to 80 bytes of extra data in an OP_RETURN output.You can read more about this and other features of the Bitcoin scripting language here.Lastly, we need to propagate this transaction into the bitcoin network.There are many ways to do that.It may take some time for it to appear.It should look something like this: From here you can do anything you want, including creating your own protocol on top of the Blockchain utilizing this embedded data.hyip bitcoin 2015One of the downsides to this, however is that such a protocol cannot support SPV (I think).bitcoin embassyThis is something I will spend some more time thinking about.jual bitcoin miningLightweight Bitcoin Wallet Securing Bitcoin payments since 2011, Electrum is one of the most popular Bitcoin wallets.cheap rdp bitcoin

Electrum is fast, secure and easy to use.It suits the needs of a wide spectrum of users.Cockbox, my VPS provider, uses the thin wallet Electrum for Bitcoin payment processing.After 7 months of experience, I think I've found out what does and doesn't work for stable, secure bitcoin payments using PHP and Electrum's JSONRPC interface.The Setup Electrum can be installed with .The only configuration that needs to be done is to enable the JSONRPC interface, and a systemd service file (or sysvinit or whatever you use).bitcoin wallet generatorIn ~/.electrum/config of whatever user is accepting payments: And the service file, in : Enabling that with will make sure Electrum always starts on boot.bitcoin sekarangLesson #1: Ship your coins off-server Don't keep your bitcoins on the server you're accepting payments on, or reuse the same wallet on your personal computer (since that is just as bad).

Instead, ship your coins to a dedicated receiving address that is part of a seperate wallet that you control.If you don't need access to these coins immediately, use a cold wallet.Lesson #2: Do not try to avoid user correlation Don't try to avoid people correlating users together or trying to map out your revenue stream.Unless you use a 3rd-party mixing service for every transaction, you are not going to be able to do it.One idea I entertained when setting this up was to use a round-robin list of bitcoin addresses payments went to, but I quickly realized that this would only require someone to look one more address back to find the same information.Lesson #3: Do not rely on Electrum notify Cockbox first launched using Electrum's notify functionality to process payments.The premise sounds nice: Via JSONRPC you request that electrum make an HTTP callback for every bitcoin transaction, and again when that transaction is confirmed.

That would be great if you could rely on the notifications coming through!Notifications are missed often enough for it to fuck up your processing completely.The Schema You need to keep track of payments somehow.This is going to be custom and tied into your application somehow, but here's what Cockbox's looks like: The custom fields here being , , and .is one of the timestamp fields in laravel, which Cockbox uses.Using JSONRPC I use this JSONRPC client, available as a composer package: Basic usage is detailed on that page.Examples for the Electrum-specific stuff we're doing is below.I'm assuming you know how to handle the rest.The Flow Now we get into the meat of things.User wants to purchase something from you with BTC, and fills out a form or something You send an request via JSONRPC, which uses or creates a BTC address for you to use .User pays BTC to the address you give them A cronjob checks every minute the unspent transactions with For each unspent, find out if the btc_tx is already saved in the table detailed above If not, and height > 0 (meaning there is at least 1 confirmation), find the pending purchase, or in this case the user's service associated with the address If the BTC amount is >= what is due, complete the payment and do any processing you need to do before #7 if the payment is confirmed Save the payment into your payments table so it isn't processed again.