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Bitcoin Script Examples

Bitcoin Scripts - Princeton University | Coursera

Bitcoin Scripts - Princeton University | Coursera

To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video To really understand what is special about Bitcoin, we need to understand how it works at a technical level. Well address the important questions about Bitcoin, such as:How does Bitcoin work? What makes Bitcoin different? How secure are your Bitcoins? How anonymous are Bitcoin users? What determines the price of Bitcoins? Can cryptocurrencies be regulated? What might the future hold?After this course, youll know everything you need to be able to separate fact from fiction when reading claims about Bitcoin and other cryptocurrencies. Youll have the conceptual foundations you need to engineer secure software that interacts with the Bitcoin network. And youll be able to integrate ideas from Bitcoin in your own projects.Course Lecturers:Arvind Narayanan, Princeton University Learn how the individual components of the Bitcoin protocol make the whole system tick: transactions, script, blocks, and the peer-to-peer network. Okay so like we said each transaction output doesn't just specify a simple public key, it actually specifies a script. So what do I mean by that, what is a script and why do we use scripts? In this section we're going to talk about what the Bitcoin scripting language is, and why script is used instead of simply assigning a public key. Okay, so to understand scripts, I think the easiest way by an example. And we'll take as an example the most common script in Bitcoin, which is to redeem a previous transaction by signing with the correct public key. So this is what the output address would look like in that case. In this case the script is gonna have four instructions so How does the script indicate who has the ability to spend these coins? The secre Continue reading >>

This Is Very Interesting:*bitcoin Has A Scripting Language Which Enables More ... | Hacker News

This Is Very Interesting:*bitcoin Has A Scripting Language Which Enables More ... | Hacker News

sillysaurus2 on Nov 24, 2013 | parent | favorite | on: Bitcoin The Internet of Money Bitcoin has a scripting language which enables more than a send money from X to Y transaction. A Bitcoin transaction can require M of N parties to approve a transaction. Imagine Wills that automatically unlock when most of the heirs agree that their parent has passed, no lawyer required. Or business accounts that require two of any three trusted signatures to approve an expenditure. Or wire escrows that go through when any arbiter agrees that the supplier sent the goods to the buyer. Or wallets that are socially secured by your friends and family. Or an allowance account accessible by the child and either of two parents. Or a crowdfunding of a Kickstarter project that pays out on milestones, based on the majority of the backers approving the next payment. The escrow in each case can be locked so that the arbiters cant take the money themselves only approve or deny the transaction. The scripting language can also unlock transactions based on other parameters. Unlocking them over time can enable automatic mortgage, trust, and allowance payouts. Unlocking them on guessable numbers creates a lottery auditable by third parties. One can even design smart property for example, a cars electronic key so that when and only when a payment is made by the car buyer to the seller, the sellers car key stops working and the buyers car key (or mobile phone) starts the car. Imagine your self-driving car negotiating traffic, paying fractional bitcoin to neighboring cars in exchange for priority. I've been following Bitcoin since the beginning and had no idea it supported "transaction approved only when M of N participants agree." How do you feel about those scenarios? Also, does anyone know of other litt Continue reading >>

Script - Bitcoin Wiki

Script - Bitcoin Wiki

Bitcoin uses a scripting system for transactions . Forth -like, Script is simple, stack-based, and processed from left to right. It is purposefully not Turing-complete, with no loops. A script is essentially a list of instructions recorded with each transaction that describe how the next person wanting to spend the Bitcoins being transferred can gain access to them. The script for a typical Bitcoin transfer to destination Bitcoin address D simply encumbers future spending of the bitcoins with two things: the spender must provide a public key that, when hashed, yields destination address D embedded in the script, and a signature to show evidence of the private key corresponding to the public key just provided. Scripting provides the flexibility to change the parameters of what's needed to spend transferred Bitcoins. For example, the scripting system could be used to require two private keys, or a combination of several, or even no keys at all. A transaction is valid if nothing in the combined script triggers failure and the top stack item is true (non-zero). The party who originally sent the Bitcoins now being spent, dictates the script operations that will occur last in order to release them for use in another transaction. The party wanting to spend them must provide the input(s) to the previously recorded script that results in those operations occurring last leaving behind true (non-zero). This document is for information purposes only. Officially Bitcoin script is defined by its reference implementation . The stacks hold byte vectors.When used as numbers, byte vectors are interpreted as little-endian variable-length integers with the most significant bit determining the sign of the integer.Thus 0x81 represents -1.0x80 is another representation of zero (so called neg Continue reading >>

The Bitcoin Script Language (pt. 1)

The Bitcoin Script Language (pt. 1)

Script is a simple scripting language, as well as the core of Bitcoin transaction processing. If you ever wrote assembly code youll find this article very easy to understand probably entertaining, otherwise it might well be one of the most challenging. Keep focused! A script is a computer program, and as a programmer you certainly know what a program is. A program takes an input, executes for some time, then returns an output. Programming languages are our tool to write programs that computers will understand, because most languages come with compilers that map human-friendly code to CPU operations, also known as opcodes. Opcodes include memory manipulation, math, loops, function calls and everything you find in procedural programming languages like C. They make up the spoken language of a CPU, the so-called machine code. Since bytes are computers preferred idiom, no wonder opcodes are bytes as well. As a result, machine code is a string of bytes representing operations to be executed on a CPU. Consider this piece of code in a high-level programming language like C: Now suppose you want to compile and run this code on a hypothetical little-endian CPU with a single cell of 16-bit memory (a register) and the following set of opcodes: A compiler for such a CPU would generate these 9 bytes of machine code: Add 4b to the register, that is now 23 + 4b = 6e. Multiply the register by 1e, yielding 6e * 1e = ce4. The register holds the final result, that is ce4. Most of the time, we need to track complex program states with variables. In C, depending on whether a variable is allocated statically or with malloc, its stored in a differently arranged memory. While malloc-ed data is accessed like an element in a very big array, static variables are pushed to and popped from a pile o Continue reading >>

Ivy For Bitcoin: A Smart Contract Language That Compiles To Bitcoinscript

Ivy For Bitcoin: A Smart Contract Language That Compiles To Bitcoinscript

Ivy for Bitcoin: a smart contract language that compiles to BitcoinScript Peter Todds SHA1 collision bounty , written inIvy Today, were delighted to release an open-source compiler and developer environment for writing Bitcoin smart contracts using Ivy, a smart contract language developed at Chain . Ivy helps you write custom, SegWit-compatible Bitcoin addresses that enforce arbitrary combinations of conditions supported by the Bitcoin protocol, including signature checks, hash commitments, and timelocks. Ivy is designed to make it easy to manipulate value the way other programming languages let you manipulate data. You can try out Ivy using the Ivy Playground for Bitcoin , and read more about it in the docs . (Please note that Ivy is relatively untested prototype software and should be used for educational and research purposes only.) If youre interested in blockchain networks, youve probably heard of smart contracts programs that can control on-chain resources using custom logic executed as part of blockchain validation. This concept is usually associated with Ethereum , which supports stateful, Turing-complete smart contracts. But did you know that you can also write smart contracts for the Bitcoin network? Bitcoin allows you to write such contracts using a low-level programming language, Bitcoin Script. Every Bitcoin address corresponds to a Bitcoin Script program. When you send bitcoins to an address, you are essentially locking them in a safety deposit box on the blockchain. These boxes are typically referred to as unspent transaction outputs, but well refer to them as contracts. Each contract has an address, which corresponds to a program that must be satisfied in order to unlock and spend the bitcoins. Bitcoin Script is the low-level assembly language used to w Continue reading >>

Deconstructing Bitcoin Transactions Part 1

Deconstructing Bitcoin Transactions Part 1

Deconstructing Bitcoin Transactions Part 1 Example 1. Pay-to-Public-Key-Hash (P2PKH) - One-to-one Transaction The majority of Bitcoin transactions today are of this general type. These types of transactions are used to transfer value, typically from one user to another. They are constructed having the form: scriptSig (or the unlocking script) first, followed by the scriptPubKey (or locking script). This example transfers the complete value from one Unspent Transaction Output (UTXO) into one address. Note: For simplification purposes, this example does not take into account a miners fee, and would most likely take additional time to be incorporated into the block chain. However, we are using the testnet where mining fees are not as strict. UTXO: 219f4b02e6e67dfbb27601449eec399f112fd3d49314aeacf63cbc5cac72c496 Pub Key: 0207c9ece04a9b5ef3ff441f3aad6bb63e323c05047a820ab45ebbe61385aa7446 Total Initial Value: 0 Satoshi (to Begin) Hover over each section of the script to see what they are. 01000000The version in Little-Endian (reversed) format 01The number of input(s)/UTXO(s) 96c472ac5cbc3cf6acae1493d4d32f119f39ec9e440176b2fb7de6e6024b9f21Previous transaction output hash, in Little-Endian. This can be found in the transaction input (txid) from your block explorer such as Chain.so. 01000000Output index output_no of the previous transaction in Little-Endian format. Again, can be found from your block explorer. 6aThe size (bytes) of the scriptSig or Unlocking Script that immediately follows. This value is in HEX as are all similar numbers and need to convert HEX to DEC to be human readable. 47PUSHDATA 47 -Size (in Bytes) to push to stack. This is also in HEX. 3044022034519a85fb5299e180865dda936c5d53edabaaf6d15cd1740aac9878b76238e002207345fcb5a62deeb8d9d80e5b412bd24d09151c2008b7f Continue reading >>

Bitcoin Script Explorer

Bitcoin Script Explorer

The Bitcoin Script Explorer is a tool to help programmers learn about Bitcoin Script . It shows all of the steps involved in executing a Bitcoin Script program. The Bitcoin blockchain consists of a sequence of transactions, where each transaction may spend the outputs of a previous transaction. Bitcoin Script is a minimal stack-based programming language. Each Bitcoin transaction has an associated Bitcoin Script program, and the result of running this program determines whether this transaction is valid or not. A Bitcoin Script program is assembled from two sections. The pubKey, which comes from the previous transaction, specifies what conditions must be met in order to spend the bitcoins from that transaction. The scriptSig, which comes from the spending transaction, satisfies these conditions. These two sources are concatenated together to form the complete Bitcoin Script program, which can then be run. The pubKey comes from the previous transaction. It specifies what conditions must be met to spend the bitcoins from that transaction, which usually consists of a proof of ownership. The goal of the pubKey section is to ensure that only desired parties may spend the bitcoins in its transaction. The pubKey forms the second part of the combined script. The scriptSig comes from the spending transaction. This section of the program satisfies the conditions imposed by the pubKey. The goal of the scriptSig section is to make the program return "success." The scriptSig forms the first part of the combined script. The script consists of a list of operators, which come from the raw hex contained in scriptSig and pubKey. Click here to return to the initial state > This shows the state of the program after the highlighted operation was run. The state consists only* of a stack of Continue reading >>

Java Code Examples Com.google.bitcoin.script.script

Java Code Examples Com.google.bitcoin.script.script

Project: bitcoinj-watcher-serviceFile: TransactionOutput.java View source code /** * Returns true if this output is to a key, or an address we have the keys for, in the wallet. */public boolean isMine(Wallet wallet) { try { Script script = getScriptPubKey(); if (script.isSentToRawPubKey()) { byte[] pubkey = script.getPubKey(); return wallet.isPubKeyMine(pubkey); } else { byte[] pubkeyHash = script.getPubKeyHash(); return wallet.isPubKeyHashMine(pubkeyHash); } } catch (ScriptException e) { // Just means we didn't understand the output of this transaction: ignore it. log.debug("Could not parse tx output script: {}", e.toString()); return false; }} Project: sparkbit-bitcoinjFile: FullBlockTestGenerator.java View source code private void addOnlyInputToTransaction(Transaction t, TransactionOutPointWithValue prevOut, long sequence) throws ScriptException { TransactionInput input = new TransactionInput(params, t, new byte[]{}, prevOut.outpoint); input.setSequenceNumber(sequence); t.addInput(input); byte[] connectedPubKeyScript = prevOut.scriptPubKey.getProgram(); Sha256Hash hash = t.hashForSignature(0, connectedPubKeyScript, SigHash.ALL, false); // Sign input try { ByteArrayOutputStream bos = new UnsafeByteArrayOutputStream(73); bos.write(coinbaseOutKey.sign(hash).encodeToDER()); bos.write(SigHash.ALL.ordinal() + 1); byte[] signature = bos.toByteArray(); Preconditions.checkState(prevOut.scriptPubKey.isSentToRawPubKey()); input.setScriptBytes(Script.createInputScript(signature)); } catch (IOException e) { throw new RuntimeException(e); // Cannot happen. }} Project: megacoinjFile: TransactionOutput.java View source code /** * Returns true if this output is to a key, or an address we have the keys for, in the wallet. */public boolean isMine(Wallet wallet) { try { Script script = Continue reading >>

Script | Bitcore

Script | Bitcore

All bitcoin transactions have scripts embedded into its inputs and outputs. The scripts use a very simple programming language, which is evaluated from left to right using a stack. The language is designed such that it guarantees all scripts will execute in a limited amount of time (it is not Turing-Complete). When a transaction is validated, the input scripts are concatenated with the output scripts and evaluated. To be valid, all transaction scripts must evaluate to true. A good analogy for how this works is that the output scripts are puzzles that specify in which conditions can those bitcoins be spent. The input scripts provide the correct data to make those output scripts evaluate to true. For more detailed information about the bitcoin scripting language, check the online reference on bitcoin's wiki . The Script object provides an interface to construct, parse, and identify bitcoin scripts. It also gives simple interfaces to create most common script types. This class is useful if you want to create custom input or output scripts. In other case, you should probably use Transaction. Here's how to use Script to create the five most common script types: This is the most commonly used transaction output script. It's used to pay to a bitcoin address (a bitcoin address is a public key hash encoded in base58check) // create a new p2pkh paying to a specific addressvar address = Address.fromString('1NaTVwXDDUJaXDQajoa9MqHhz4uTxtgK14');var script = Script.buildPublicKeyHashOut(address);assert(script.toString() === 'OP_DUP OP_HASH160 20 0xecae7d092947b7ee4998e254aa48900d26d2ce1d OP_EQUALVERIFY OP_CHECKSIG'); Pay to public key scripts are a simplified form of the p2pkh, but aren't commonly used in new transactions anymore, because p2pkh scripts are more secure (the public ke Continue reading >>

Learning-bitcoin-from-the-command-line/07_2_running_a_bitcoin_script.md At Master Christophera/learning-bitcoin-from-the-command-line Github

Learning-bitcoin-from-the-command-line/07_2_running_a_bitcoin_script.md At Master Christophera/learning-bitcoin-from-the-command-line Github

From some appropriate folder (e.g. ~/workspace), clone the btcdeb project from Github and compile/install it. $ sudo apt-get install git$ git clone Then, get C++ and other packages installed, so that you can get btcdeb running. $ sudo apt-get install autoconf$ sudo apt-get install libtool$ sudo apt-get install g++$ sudo apt-get install pkg-config$ sudo apt-get install make$ cd btcdeb$ ./autogen.sh$ ./configure$ make$ sudo make install After all of that, you should have a copy of btcdeb: It is recommended that you all install readline, as this makes the debugger a lot easier to use by supporting history using up/down arrows, left-right movement, autocompletion using tab, etc. The package is usually called libreadline-dev (linux) or just readline (mac). btcdeb takes a script, as well as any number of stack entries, as startup arguments. If you start it up with no arguments, you simply get an interpreterwhere you may issue exec [opcode] commands to perform actions directly. btcc takes script opcodes and data and outputs a Bitcoin Script in hexadecimal form. We will make use of both of these in the sections below. A Bitcoin Script has three parts: it has a line of input; it has a stack for storage; and it has specific commands for execution. Bitcoin Scripts are run from left to right. That sounds easy enough, because it's the same way you read. However, it might actually be the most non-intuitive element of Bitcoin Script, because it means that functions don't look like you'd expect. Instead, the operands go before the operator. For example, if you were adding together "1" and "2", your Bitcoin Script for that would be 1 2 OP_ADD, not "1 + 2". Since we know that OP_ADD operator takes two inputs, we know that the two inputs before it are its operands. WARNING: Technically, Continue reading >>

Any Examples Of The

Any Examples Of The "10 Minute Script" That's A Theoretical Danger In 2mb Blocks? : Bitcoin

Do not use URL shortening services: always submit the real link. Begging/asking for bitcoins is absolutely not allowed, no matter how badly you need the bitcoins. Only requests for donations to large, recognized charities are allowed, and only if there is good reason to believe that the person accepting bitcoins on behalf of the charity is trustworthy. News articles that do not contain the word "Bitcoin" are usually off-topic. This subreddit is not about general financial news. Submissions that are mostly about some other cryptocurrency belong elsewhere. For example, /r/CryptoCurrency is a good place to discuss all cryptocurrencies. Promotion of client software which attempts to alter the Bitcoin protocol without overwhelming consensus is not permitted. Trades should usually not be advertised here. For example, submissions like "Buying 100 BTC" or "Selling my computer for bitcoins" do not belong here. /r/Bitcoin is primarily for news and discussion. Please avoid repetition /r/bitcoin is a subreddit devoted to new information and discussion about Bitcoin and its ecosystem. New merchants are welcome to announce their services for Bitcoin, but after those have been announced they are no longer news and should not be re-posted. Aside from new merchant announcements, those interested in advertising to our audience should consider Reddit's self-serve advertising system . Do not post your Bitcoin address unless someone explicitly asks you to. Be aware that Twitter, etc. is full of impersonation. Continue reading >>

How A Bitcoin Transaction Works

How A Bitcoin Transaction Works

Join our community of 10 000 traders on Hacked.com for just $39 per month. This article explains what a Bitcoin transaction is, its purpose and outcome. The explanation made below is suitable for both novice and intermediate Bitcoin users. As a cryptocurrency user you need to be familiar with transaction rudiments – for the sake of your own confidence with this evolving innovation, and as a foundation for understanding emerging multi-signature transactions and contracts, both of which will be explored later in the series. This is not a technical article and explanation will focus on what you need to know about standard bitcoin transactions – the spend transactions we commonly make – and we’ll gloss over what you can safely ignore. An infographic at the bottom of the article provides a comprehensive illustration of the entire Bitcoin transaction process from wallet to blockchain. Note: Even the Core developers acknowledge that some of the language being used to describe transactions and their components can lead one to a mistaken concept of what is really happening. These misconceptions are avoided in the explanation below. So, while trying to keep things as simple as possible, and with the aid of a few diagrams, let’s dive right in. Bitcoin with a capital “B” refers to the protocol – the code, the nodes, the network and their peer-to-peer interaction. bitcoin with a lowercase ‘b’ refers to the currency – the cryptocurrency we send and receive, via the Bitcoin network. tx – wherever it is used in the text – is an abbreviation for ‘ Bitcoin transaction ‘ txid is an abbreviation for ‘transaction id’ – this is a hash that is used by both humans and the protocol to reference transactions. Script is the name of the Bitcoin protocol’s scr Continue reading >>

Smart Contracts And Bitcoin Manuel Araoz Medium

Smart Contracts And Bitcoin Manuel Araoz Medium

Project lead at OpenZeppelin. CTO at Zeppelin Solutions Smart contract is a term coined by Nick Szabo around 1993. It refers to computer programs or systems used to secure, execute and enforce interactions between parties. The idea behind this is to transfer trust-critical pieces of a contract to software, to formalize the relation in code. Thus, if one can trust the program executing the contract, one does not need to trust the other party in that they will fulfill the terms. The value and applications of this are still uncertain, but we can begin to see the great potential for transforming how we do business online. Automating complex human processes has been the cornerstone of technological progress in society. Law and contractual relations have yet to feel the vertiginous acceleration of software-driven innovation. Since its origin, bitcoin comes with a limited but powerful scripting language to express transfer of ownership of coins. When a transaction sends coins from A to B, theres actually a script expressing the conditions in which B can take ownership of those coins. In the simple case, B needs to produce a cryptographic signature corresponding to a certain public key. In a general sense, a transaction output sets the rules (via a script) by which it can be spent, and a future transaction needs to produce the data input for that script to execute successfully. Most bitcoin transactions follow a predefined type of script where the coins move from A to B. In the past months, though, weve seen a surge in new contracts being built using the scripting language. Lets see some examples of this, and the corresponding scripts. The first ever alternative behavior attached to bitcoins. Its really simple to understand: instead of having a single entity own the coins, we Continue reading >>

Bitcoin Multisig The Hard Way: Understanding Raw P2sh Multisig Transactions

Bitcoin Multisig The Hard Way: Understanding Raw P2sh Multisig Transactions

Bitcoin multisig the hard way: Understanding raw P2SH multisig transactions Recently, inspired by Ken Shirriff's and Bryce Neal's low level looks at the Bitcoin protocol, I set about constructing Bitcoin's much talked about multisignature transactions from scratch to understand their capabilities and limitations. Specifically, I used Bitcoin's Pay-to-ScriptHash (P2SH) transaction type to create a M-of-N multisignature transaction. The code to do it all in Go is available as go-bitcoin-multsig on GitHub and I'd like to go through how all of this works at the Bitcoin protocol level. We'll also step through creating and spending a multisig transaction to make it all clearer. In many ways, this is a follow up to Ken's amazing explanation of the Bitcoin protocol and constructing a Pay-to-PubKeyHash (P2PKH) transaction, so I won't cover things covered there in any great detail. Please check out his post out first if you're completely new to the Bitcoin protocol. I'll be using go-bitcoin-multisig to generate keys and transactions along the way, explaining each step. If you'd like to follow along and create a multisig transaction yourself, you'll need to follow the simple build instructions for go-bitcoin-multisig . What is a Pay-to-ScriptHash (P2SH) transaction? A typical Bitcoin address that looks like 15Cytz9sHqeqtKCw2vnpEyNQ8teKtrTPjp is actually a specific type of Bitcoin address known as a Pay-to-PubKeyHash (P2PKH) address. To spend Bitcoin funds sent to this type of address, the recipient must use the private key associated with the public key hash specified in that address to create a digital signature, which is put into the scriptSig of a spending transaction, unlocking the funds. A Pay-to-ScriptHash (P2SH) Bitcoin address looks and works quite differently. A typical Continue reading >>

Developer Examples - Bitcoin

Developer Examples - Bitcoin

BETA: This documentation has not been extensively reviewed by Bitcoin experts and so likely contains numerous errors. Please use the Issue and Edit links on the bottom left menu to help us improve. Click here to close this disclaimer. X The following guide aims to provide examples to help you startbuilding Bitcoin-based applications. To make the best use of this document,you may want to install the current version of Bitcoin Core, either from source or from a pre-compiled executable . Once installed, youll have access to three programs: bitcoind,bitcoin-qt, and bitcoin-cli. bitcoin-qt provides a combination full Bitcoin peer and wallet frontend. From the Help menu, you can access a console where you canenter the RPC commands used throughout this document. bitcoind is more useful for programming: it provides a full peer which you can interact with through RPCs to port 8332 (or 18332for testnet ). bitcoin-cli allows you to send RPC commands to bitcoind from thecommand line. For example, bitcoin-cli help All three programs get settings from bitcoin.conf in the Bitcoinapplication directory: OSX: $HOME/Library/Application Support/Bitcoin/ To use bitcoind and bitcoin-cli, you will need to add a RPC passwordto your bitcoin.conf file. Both programs will read from the same fileif both run on the same system as the same user, so any long randompassword will work: rpcpassword=change_this_to_a_long_random_password You should also make the bitcoin.conf file only readable to itsowner. On Linux, Mac OSX, and other Unix-like systems, this can beaccomplished by running the following command in the Bitcoin applicationdirectory: For development, its safer and cheaper to use Bitcoins test network ( testnet )or regression test mode ( regtest ) described below. Questions about Bitcoin use a Continue reading >>

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