Jump to: , 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 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 negative 0).Positive 0 is represented by a null-length vector.Byte vectors are interpreted as Booleans where False is represented by any representation of zero, and True is represented by any representation of non-zero.Contents 1 2 3 4 This is a list of all Script words, also known as opcodes, commands, or functions.There are some words which existed in very early versions of Bitcoin but were removed out of a concern that the client might have a bug in their implementation.

This fear was motivated by a bug found in OP_LSHIFT which could crash any Bitcoin node if exploited, and by other bugs in how Script worked which allowed anyone to spend anyone's bitcoins.The removed opcodes are sometimes said to be "disabled" opcodes, but this is something of a misnomer because there is absolutely no way for anyone using Bitcoin to use these opcodes (they simply do not exist anymore in the protocol), and there are also no solid plans to ever re-enable all of these opcodes.They are listed here only for historical interest.New opcodes can be added by means of a carefully designed and executed softfork using OP_NOP1-OP_NOP10.False is zero or negative zero (using any number of bytes) or an empty array, and True is anything else.When talking about scripts, these value-pushing words are usually omitted.If any opcode marked as disabled is present in a script, it must abort and fail.Note: Arithmetic inputs are limited to signed 32-bit integers, but may overflow their output.If any input value for any of these commands is longer than 4 bytes, the script must abort and fail.

If any opcode marked as disabled is present in a script - it must also abort and fail.These words are used internally for assisting with transaction matching.They are invalid if used in actual scripts.Any opcode not assigned is also reserved.dogecoin transactionsUsing an unassigned opcode makes the transaction invalid.ethereum vpnThis is a list of interesting scripts.litecoin za smsKeep in mind that all constants actually use the data-pushing commands above.bitcoin seminar reportNote that there is a small number of standard script forms that are relayed from node to node; non-standard scripts are accepted if they are in a block, but nodes will not relay them.bitcoin scrypt

To demonstrate how scripts look on the wire, here is a raw scriptPubKey: Note: scriptSig is in the input of the spending transaction and scriptPubKey is in the output of the previously unspent i.e.Here is how each word is processed: OP_CHECKSIG is used directly without first hashing the public key.bitcoin difficulty growth rateThis was used by early versions of Bitcoin where people paid directly to IP addresses, before Bitcoin addresses were introduced.scriptPubKeys of this transaction form are still recognized as payments to user by Bitcoin Core.The disadvantage of this transaction form is that the whole public key needs to be known in advance, implying longer payment addresses, and that it provides less protection in the event of a break in the ECDSA signature algorithm.The standard way to mark a transaction as provably unspendable is with a scriptPubKey of the following form: OP_RETURN immediately marks the script as invalid, guaranteeing that no scriptSig exists that could possibly spend that output.

Thus the output can be immediately pruned from the UTXO set even if it has not been spent.eb31ca1a4cbd97c2770983164d7560d2d03276ae1aee26f12d7c2c6424252f29 is an example: it has a single output of zero value, thus giving the full 0.125BTC fee to the miner who mined the transaction without adding an entry to the UTXO set.You can also use OP_RETURN to add data to a transaction without the data ever appearing in the UTXO set, as seen in 1a2e22a717d626fc5db363582007c46924ae6b28319f07cb1b907776bd8293fc; P2Pool does this with the share chain hash txout in the coinbase of blocks it creates.Conversely a transaction can be made spendable by anyone at all: With some software changes such transactions can be used as a way to donate funds to miners in addition to transaction fees: any miner who mines such a transaction can also include an additional one after it sending the funds to an address they control.This mechanism may be used in the future for fidelity bonds to sacrifice funds in a provable way.