Expand description

Miniscript and Output Descriptors


Bitcoin Script

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 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


Deriving an address from a descriptor

extern crate bitcoin;
extern crate miniscript;

use std::str::FromStr;
use miniscript::NullCtx;

fn main() {
    let desc = miniscript::Descriptor::<

    // Sometimes it is necessary to have additional information to get the bitcoin::PublicKey
    // from the MiniscriptKey which can supplied by `to_pk_ctx` parameter. For example,
    // when calculating the script pubkey of a descriptor with xpubs, the secp context and
    // child information maybe required.

    // Derive the P2SH address
        desc.address(bitcoin::Network::Bitcoin, NullCtx).unwrap().to_string(),

    // Check whether the descriptor is safe
    // This checks whether all spend paths are accessible in bitcoin network.
    // It maybe possible that some of the spend require more than 100 elements in Wsh scripts
    // Or they contain a combination of timelock and heightlock.

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


pub extern crate bitcoin;
pub use descriptor::Descriptor;
pub use descriptor::DescriptorPublicKey;
pub use descriptor::DescriptorPublicKeyCtx;
pub use interpreter::Interpreter;
pub use miniscript::decode::Terminal;
pub use miniscript::satisfy::BitcoinSig;
pub use miniscript::satisfy::Satisfier;
pub use miniscript::Miniscript;


Output Descriptors

Function-like Expression Language


Abstract Syntax Tree

Script Policies

Partially-Signed Bitcoin Transactions


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

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

Dummy Context for impl for ToPublicKey for bitcoin::PublicKey


Bare ScriptContext To be used as raw script pubkeys In general, it is not recommended to use Bare descriptors as they as strongly limited by standardness policies.


Legacy ScriptContext To be used as P2SH scripts For creation of Bare scriptpubkeys, construct the Miniscript under Bare ScriptContext

Segwitv0 ScriptContext


Public key trait which can be converted to Hash type

The ScriptContext for Miniscript. Additional type information associated with miniscript that is used for carrying out checks that dependent on the context under which the script is used. For example, disallowing uncompressed keys in Segwit context

Trait describing public key types which can be converted to bitcoin pubkeys The trait relies on Copy trait because in all practical usecases ToPkCtx should contain references to objects which should be cheap to Copy.


The size of an encoding of a number in Script