Crate miniscript

Expand description

Miniscript and Output Descriptors

In Bitcoin, spending policies are defined and enforced by means of a stack-based programming language known as Bitcoin Script. While this language appears to be designed with tractable analysis in mind (e.g. there are no looping or jumping constructions), in practice this is extremely difficult. As a result, typical wallet software supports only a small set of script templates, cannot interoperate with other similar software, and each wallet contains independently written ad-hoc manually verified code to handle these templates. Users who require more complex spending policies, or who want to combine signing infrastructure which was not explicitly designed to work together, are simply out of luck.

Miniscript

Miniscript is an alternative to Bitcoin Script which eliminates these problems. It can be efficiently and simply encoded as Script to ensure that it works on the Bitcoin blockchain, but its design is very different. Essentially, a Miniscript is a monotone function (tree of ANDs, ORs and thresholds) of signature requirements, hash preimage requirements, and timelocks.

A full description of Miniscript is available here.

Miniscript also admits a more human-readable encoding.

Output Descriptors

While spending policies in Bitcoin are entirely defined by Script; there are multiple ways of embedding these Scripts in transaction outputs; for example, P2SH or Segwit v0. These different embeddings are expressed by Output Descriptors, which are described here

Examples

Deriving an address from a descriptor

extern crate bitcoin;
extern crate miniscript;

use std::str::FromStr;

fn main() {
    let desc = miniscript::Descriptor::<
        bitcoin::PublicKey,
    >::from_str("\
        sh(wsh(or_d(\
            c:pk_k(020e0338c96a8870479f2396c373cc7696ba124e8635d41b0ea581112b67817261),\
            c:pk_k(020e0338c96a8870479f2396c373cc7696ba124e8635d41b0ea581112b67817261)\
        )))\
    ").unwrap();

    // Derive the P2SH address
    assert_eq!(
        desc.address(bitcoin::Network::Bitcoin).unwrap().to_string(),
        "32aAVauGwencZwisuvd3anhhhQhNZQPyHv"
    );

    // Estimate the satisfaction cost
    assert_eq!(desc.max_satisfaction_weight(), 293);
}

Re-exports

pub extern crate bitcoin;

pub use descriptor::Descriptor;

pub use miniscript::decode::Terminal;

pub use miniscript::satisfy::BitcoinSig;

pub use miniscript::satisfy::Satisfier;

pub use miniscript::Miniscript;

Modules

descriptor

Output Descriptors

expression

Function-like Expression Language

miniscript

Abstract Syntax Tree

policy

Script Policies

psbt

Partially-Signed Bitcoin Transactions

Structs

DummyKey

Dummy key which de/serializes to the empty string; useful sometimes for testing

DummyKeyHash

Dummy keyhash which de/serializes to the empty string; useful sometimes for testing

SatisfiedConstraints

An iterator over all the satisfied constraints satisfied by a given descriptor/scriptSig/witness stack tuple. This returns all the redundant satisfied constraints even if they were not required for the entire satisfaction. For example, and_b(Pk,false) would return the witness for Pk if it was satisfied even if the entire and_b could have failed. In case the script would abort on the given witness stack OR if the entire script is dissatisfied, this would return keep on returning values _until_Error.

Enums

Error

Miniscript

Legacy

Legacy ScriptContext

Segwitv0

Segwitv0 ScriptContext

Traits

MiniscriptKey

Public key trait which can be converted to Hash type

ScriptContext

ToPublicKey

Trait describing public key types which can be converted to bitcoin pubkeys

Functions

script_num_size

The size of an encoding of a number in Script