Crate bitcoin_scripts
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Bitcoin script types
Bitcoin doesn’t make a distinction between Bitcoin script coming from
different sources, like scriptPubKey in transaction output or witness
and scriptSig in transaction input. There are many other possible script
containers for Bitcoin script: redeem script, witness script, taproot leaf
bitcoin_scripts of different versions. In fact, any “script” of
bitcoin::Script
type can be used for inputs and outputs. What is a valid
script for in one context will not be a valid script for some other. That
would mean that in principle with existing bitcoin::Script
type every
input script can be used as an output script, leading to potentially harmful
code coming from an unaware developer.
While all bitcoin::Script
s have the same parsing rules converting byte
string into a set of instructions (i.e. the same syntax), there are
multiple ways how the consensus meaning of these instructions will be
interpreted under different contexts (different semantics). Moreover,
the bitcoin_scripts may be nested - or to be committed into some other
Bitcoin script – in a nested structures like in several layers, like
redeemScript inside of scriptSig used for P2SH, or tapScript within
witnessScript coming from witness field for Taproot. These nested layers
do distinguish on the information they contain, since some of them only
commit to the hashes of the nested bitcoin_scripts (bitcoin::ScriptHash
,
WitnessProgram
) or public keys (bitcoin::PubkeyHash
,
bitcoin::WPubkeyHash
), while other contain the full source of the
script.
The present type system represents a solution to the problem: it distinguish
different logical types by introducing Script
wrapper types. It defines
LockScript
as bottom layer of a script, containing no other script
commitments (in form of their hashes). It also defines types above on it:
PubkeyScript
(for whatever is there in scriptPubkey
field
of a bitcoin::TxOut
), SigScript
(for whatever comes from scriptSig
field of bitcoin::TxIn
), RedeemScript
and WitnessScript
.
For taproot, we define LeafScript
as a top level of specific script
branch (see bitcoin::util::psbt::TapTree
) and crate::TapScript
as a
type specific for the current 0xC0
tapleaf version semantics, defined in
BIP-342.
There are conversion functions, which, for instance, can analyse
PubkeyScript
and if it is a custom script or P2PK return a
LockScript
type - or otherwise fail with error. These conversions
functions reside in convert
module. So with this type system one is
always sure which semantic information it does contain.
Type conversion
LockScript -+-> (PubkeyScript + RedeemScript) -+-> SigScript
| +-> WitnessScript
+-> PubkeyScript
|
TapScript ----> LeafScript
PubkeyScript --?--> LockScript
Re-exports
pub use convert::ConvertInfo;
Modules
- Address-related types for detailed payload analysis and memory-efficient processing.
- Helper traits and supplementary types for converting different types of bitcoin_scripts and keys into each other.
- Hash-locked contract supporting data structures.
- Taproot script tree implementation allowing arbitrary tree processing/ modification (see
TaprootScriptTree
structure).
Structs
- Any valid branch of taproot script spending
- Script whose knowledge and satisfaction is required for spending some specific transaction output. This is the deepest nested version of Bitcoin script containing no hashes of other bitcoin_scripts, including P2SH
redeemScript
hashes orwitnessProgram
(hash or witness script), or public key hashes. It is also used for representing specific spending branch of the taproot script tree. - A content of
scriptPubkey
from a transaction output - Redeem script as part of the
witness
orscriptSig
structure; it is hashed for P2(W)SH output. - A representation of
scriptPubkey
data used during SegWit signing procedure - Scripting data for both transaction output and spending transaction input parts that can be generated from some complete bitcoin Script (
LockScript
) or public key using particularcrate::ConvertInfo
- A content of
scriptSig
from a transaction input - Script at specific taproot script spend path for
0xC0
tapleaf version, which semantics are defined in BIP-342. - Witness program: a part of post-segwit
scriptPubkey
; a data pushed to the stack following witness version - A content of the script from
witness
structure; en equivalent ofredeemScript
for witness-based transaction inputs. However, unlikeRedeemScript
,WitnessScript
produce SHA256-based hashes ofWScriptHash
type.
Enums
- Parsed witness stack for Taproot inputs
- Errors for
TaprootWitness
construction fromWitness
and byte representations
Traits
- Marker trait for all forms of hashes which may participate in the construction of taproot script tree.
Type Definitions
- The hash value of a taptree node which may be a leaf node, branch node or a hidden node.