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Merge pull request #493 from theStack/isstandard

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replace "isStandard" by "IsStandard" (ref. to Bitcoin Core function)
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Andreas M. Antonopoulos 2018-02-03 14:05:04 -08:00 committed by GitHub
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8
ch07.asciidoc
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@ -12,7 +12,9 @@ First, we will look at _multisignature_ scripts. Next, we will examine the secon
[[multisig]]
=== Multisignature
((("transactions", "advanced", "multisignature scripts")))((("transactions", "advanced", id="Tadv07")))((("scripting", "multisignature scripts", id="Smulti07")))((("multisignature scripts")))Multisignature scripts set a condition where N public keys are recorded in the script and at least M of those must provide signatures to unlock the funds. This is also known as an M-of-N scheme, where N is the total number of keys and M is the threshold of signatures required for validation. For example, a 2-of-3 multisignature is one where three public keys are listed as potential signers and at least two of those must be used to create signatures for a valid transaction to spend the funds. At this time, standard multisignature scripts are limited to at most 15 listed public keys, meaning you can do anything from a 1-of-1 to a 15-of-15 multisignature or any combination within that range. The limitation to 15 listed keys might be lifted by the time this book is published, so check the +isStandard()+ function to see what is currently accepted by the network.
((("transactions", "advanced", "multisignature scripts")))((("transactions", "advanced", id="Tadv07")))((("scripting", "multisignature scripts", id="Smulti07")))((("multisignature scripts")))Multisignature scripts set a condition where N public keys are recorded in the script and at least M of those must provide signatures to unlock the funds. This is also known as an M-of-N scheme, where N is the total number of keys and M is the threshold of signatures required for validation. For example, a 2-of-3 multisignature is one where three public keys are listed as potential signers and at least two of those must be used to create signatures for a valid transaction to spend the funds.
At this time, _standard_ multisignature scripts are limited to at most 3 listed public keys, meaning you can do anything from a 1-of-1 to a 3-of-3 multisignature or any combination within that range. The limitation to 3 listed keys might be lifted by the time this book is published, so check the +IsStandard()+ function to see what is currently accepted by the network. Note that the limit of 3 keys applies only to standard (also known as "bare") multisignature scripts, not to multisignature scripts wrapped in a Pay-to-Script-Hash (P2SH) script. P2SH multisignature scripts are limited to 15 keys, allowing for up to 15-of-15 multisignature. We will learn about P2SH in <<p2sh>>.
The general form of a locking script setting an M-of-N multisignature condition is:
@ -209,7 +211,7 @@ P2SH addresses hide all of the complexity, so that the person making a payment d
==== Redeem Script and Validation
((("scripting", "Pay-to-Script-Hash", "redeem scripts and validation")))((("Pay-to-Script-Hash (P2SH)", "redeem scripts and validation")))((("redeem scripts")))((("validation")))Prior to version 0.9.2 of the Bitcoin Core client, Pay-to-Script-Hash was limited to the standard types of bitcoin transaction scripts, by the +isStandard()+ function. That means that the redeem script presented in the spending transaction could only be one of the standard types: P2PK, P2PKH, or multisig nature, excluding +RETURN+ and P2SH itself.
((("scripting", "Pay-to-Script-Hash", "redeem scripts and validation")))((("Pay-to-Script-Hash (P2SH)", "redeem scripts and validation")))((("redeem scripts")))((("validation")))Prior to version 0.9.2 of the Bitcoin Core client, Pay-to-Script-Hash was limited to the standard types of bitcoin transaction scripts, by the +IsStandard()+ function. That means that the redeem script presented in the spending transaction could only be one of the standard types: P2PK, P2PKH, or multisig, excluding +RETURN+ and P2SH itself.
As of version 0.9.2 of the Bitcoin Core client, P2SH transactions can contain any valid script, making the P2SH standard much more flexible and allowing for experimentation with many novel and complex types of transactions.
@ -243,7 +245,7 @@ RETURN <data>
Keep in mind that there is no "unlocking script" that corresponds to +RETURN+ that could possibly be used to "spend" a +RETURN+ output. The whole point of +RETURN+ is that you can't spend the money locked in that output, and therefore it does not need to be held in the UTXO set as potentially spendable—+RETURN+ is _provably unspendable_. +RETURN+ is usually an output with a zero bitcoin amount, because any bitcoin assigned to such an output is effectively lost forever. If a +RETURN+ is referenced as an input in a transaction, the script validation engine will halt the execution of the validation script and mark the transaction as invalid. The execution of +RETURN+ essentially causes the script to "RETURN" with a +FALSE+ and halt. Thus, if you accidentally reference a +RETURN+ output as an input in a transaction, that transaction is invalid.
A standard transaction (one that conforms to the +isStandard()+ checks) can have only one +RETURN+ output. However, a single +RETURN+ output can be combined in a transaction with outputs of any other type.
A standard transaction (one that conforms to the +IsStandard()+ checks) can have only one +RETURN+ output. However, a single +RETURN+ output can be combined in a transaction with outputs of any other type.
Two new command-line options have been added in Bitcoin Core as of version 0.10. The option +datacarrier+ controls relay and mining of +RETURN+ transactions, with the default set to "1" to allow them. The option +datacarriersize+ takes a numeric argument specifying the maximum size in bytes of the +RETURN+ script, 83 bytes by default, which, allows for a maximum of 80 bytes of +RETURN+ data plus one byte of +RETURN+ opcode and two bytes of +PUSHDATA+ opcode.

2
ch10.asciidoc
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@ -113,7 +113,7 @@ Each node verifies every transaction against a long checklist of criteria:
* +nLocktime+ is equal to +INT_MAX+, or +nLocktime+ and +nSequence+ values are satisfied according to +MedianTimePast+.
* The transaction size in bytes is greater than or equal to 100.
* The number of signature operations (SIGOPS) contained in the transaction is less than the signature operation limit.
* The unlocking script (+scriptSig+) can only push numbers on the stack, and the locking script (+scriptPubkey+) must match +isStandard+ forms (this rejects "nonstandard" transactions).
* The unlocking script (+scriptSig+) can only push numbers on the stack, and the locking script (+scriptPubkey+) must match +IsStandard+ forms (this rejects "nonstandard" transactions).
* A matching transaction in the pool, or in a block in the main branch, must exist.
* For each input, if the referenced output exists in any other transaction in the pool, the transaction must be rejected.
* For each input, look in the main branch and the transaction pool to find the referenced output transaction. If the output transaction is missing for any input, this will be an orphan transaction. Add to the orphan transactions pool, if a matching transaction is not already in the pool.