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// Miniscript // Written in 2019 by // Andrew Poelstra <apoelstra@wpsoftware.net> // // To the extent possible under law, the author(s) have dedicated all // copyright and related and neighboring rights to this software to // the public domain worldwide. This software is distributed without // any warranty. // // You should have received a copy of the CC0 Public Domain Dedication // along with this software. // If not, see <http://creativecommons.org/publicdomain/zero/1.0/>. // //! Miniscript and Output Descriptors //! //! # Introduction //! ## 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 //! //! 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](http://bitcoin.sipa.be/miniscript/miniscript.html). //! //! 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](https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md) //! //! # Examples //! //! ## Deriving an address from a descriptor //! //! ```rust //! 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(020e0338c96a8870479f2396c373cc7696ba124e8635d41b0ea581112b67817261),\ //! c:pk(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); //! } //! ``` //! //! #![cfg_attr(all(test, feature = "unstable"), feature(test))] pub extern crate bitcoin; #[cfg(feature = "serde")] pub extern crate serde; #[cfg(all(test, feature = "unstable"))] extern crate test; #[macro_use] #[cfg(test)] mod macros; pub mod descriptor; pub mod expression; pub mod miniscript; pub mod policy; pub mod psbt; use std::str::FromStr; use std::{error, fmt, hash, str}; use bitcoin::blockdata::{opcodes, script}; use bitcoin::hashes::{hash160, sha256, Hash}; pub use descriptor::{Descriptor, SatisfiedConstraints}; pub use miniscript::decode::Terminal; pub use miniscript::satisfy::{BitcoinSig, Satisfier}; pub use miniscript::Miniscript; ///Public key trait which can be converted to Hash type pub trait MiniscriptKey: Clone + Eq + Ord + str::FromStr + fmt::Debug + fmt::Display + hash::Hash { type Hash: Clone + Eq + Ord + str::FromStr + fmt::Display + fmt::Debug + hash::Hash; ///Converts an object to PublicHash fn to_pubkeyhash(&self) -> Self::Hash; } impl MiniscriptKey for bitcoin::PublicKey { type Hash = hash160::Hash; fn to_pubkeyhash(&self) -> Self::Hash { let mut engine = hash160::Hash::engine(); self.write_into(&mut engine); hash160::Hash::from_engine(engine) } } impl MiniscriptKey for String { type Hash = String; fn to_pubkeyhash(&self) -> Self::Hash { format!("{}", &self) } } /// Trait describing public key types which can be converted to bitcoin pubkeys pub trait ToPublicKey: MiniscriptKey { /// Converts an object to a public key fn to_public_key(&self) -> bitcoin::PublicKey; /// Computes the size of a public key when serialized in a script, /// including the length bytes fn serialized_len(&self) -> usize { if self.to_public_key().compressed { 34 } else { 66 } } /// Converts a hashed version of the public key to a `hash160` hash. /// /// This method must be consistent with `to_public_key`, in the sense /// that calling `MiniscriptKey::to_pubkeyhash` followed by this function /// should give the same result as calling `to_public_key` and hashing /// the result directly. fn hash_to_hash160(hash: &<Self as MiniscriptKey>::Hash) -> hash160::Hash; } impl ToPublicKey for bitcoin::PublicKey { fn to_public_key(&self) -> bitcoin::PublicKey { *self } fn hash_to_hash160(hash: &hash160::Hash) -> hash160::Hash { *hash } } /// Dummy key which de/serializes to the empty string; useful sometimes for testing #[derive(Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Debug)] pub struct DummyKey; impl str::FromStr for DummyKey { type Err = &'static str; fn from_str(x: &str) -> Result<DummyKey, &'static str> { if x.is_empty() { Ok(DummyKey) } else { Err("non empty dummy key") } } } impl MiniscriptKey for DummyKey { type Hash = DummyKeyHash; fn to_pubkeyhash(&self) -> Self::Hash { DummyKeyHash } } impl hash::Hash for DummyKey { fn hash<H: hash::Hasher>(&self, state: &mut H) { "DummyKey".hash(state); } } impl fmt::Display for DummyKey { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.write_str("") } } impl ToPublicKey for DummyKey { fn to_public_key(&self) -> bitcoin::PublicKey { bitcoin::PublicKey::from_str( "0250863ad64a87ae8a2fe83c1af1a8403cb53f53e486d8511dad8a04887e5b2352", ) .unwrap() } fn hash_to_hash160(_: &DummyKeyHash) -> hash160::Hash { hash160::Hash::from_str("f54a5851e9372b87810a8e60cdd2e7cfd80b6e31").unwrap() } } /// Dummy keyhash which de/serializes to the empty string; useful sometimes for testing #[derive(Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Debug)] pub struct DummyKeyHash; impl str::FromStr for DummyKeyHash { type Err = &'static str; fn from_str(x: &str) -> Result<DummyKeyHash, &'static str> { if x.is_empty() { Ok(DummyKeyHash) } else { Err("non empty dummy key") } } } impl fmt::Display for DummyKeyHash { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.write_str("") } } impl hash::Hash for DummyKeyHash { fn hash<H: hash::Hasher>(&self, state: &mut H) { "DummyKeyHash".hash(state); } } /// Miniscript #[derive(Debug)] pub enum Error { /// Opcode appeared which is not part of the script subset InvalidOpcode(opcodes::All), /// Some opcode occurred followed by `OP_VERIFY` when it had /// a `VERIFY` version that should have been used instead NonMinimalVerify(miniscript::lex::Token), /// Push was illegal in some context InvalidPush(Vec<u8>), /// PSBT-related error Psbt(psbt::Error), /// rust-bitcoin script error Script(script::Error), /// A `CHECKMULTISIG` opcode was preceded by a number > 20 CmsTooManyKeys(u32), /// Encountered unprintable character in descriptor Unprintable(u8), /// expected character while parsing descriptor; didn't find one ExpectedChar(char), /// While parsing backward, hit beginning of script UnexpectedStart, /// Got something we were not expecting Unexpected(String), /// Name of a fragment contained `:` multiple times MultiColon(String), /// Name of a fragment contained `@` multiple times MultiAt(String), /// Name of a fragment contained `@` but we were not parsing an OR AtOutsideOr(String), /// Fragment was an `and_v(_, true)` which should be written as `t:` NonCanonicalTrue, /// Fragment was an `or_i(_, false)` or `or_i(false,_)` which should be written as `u:` or `l:` NonCanonicalFalse, /// Encountered a `l:0` which is syntactically equal to `u:0` except stupid LikelyFalse, /// Encountered a wrapping character that we don't recognize UnknownWrapper(char), /// Parsed a miniscript and the result was not of type T NonTopLevel(String), /// Parsed a miniscript but there were more script opcodes after it Trailing(String), /// Failed to parse a push as a public key BadPubkey(bitcoin::consensus::encode::Error), /// Could not satisfy a script (fragment) because of a missing hash preimage MissingHash(sha256::Hash), /// Could not satisfy a script (fragment) because of a missing signature MissingSig(bitcoin::PublicKey), /// Could not satisfy, relative locktime not met RelativeLocktimeNotMet(u32), /// Could not satisfy, absolute locktime not met AbsoluteLocktimeNotMet(u32), /// General failure to satisfy CouldNotSatisfy, /// Typechecking failed TypeCheck(String), ///General error in creating descriptor BadDescriptor, ///Forward-secp related errors Secp(bitcoin::secp256k1::Error), #[cfg(feature = "compiler")] ///Compiler related errors CompilerError(policy::compiler::CompilerError), ///Interpreter related errors InterpreterError(descriptor::InterpreterError), /// Bad Script Sig. As per standardness rules, only pushes are allowed in /// scriptSig. This error is invoked when op_codes are pushed onto the stack /// As per the current implementation, pushing an integer apart from 0 or 1 /// will also trigger this. This is because, Miniscript only expects push /// bytes for pk, sig, preimage etc or 1 or 0 for `StackElement::Satisfied` /// or `StackElement::Dissatisfied` BadScriptSig, ///Witness must be empty for pre-segwit transactions NonEmptyWitness, ///ScriptSig must be empty for pure segwit transactions NonEmptyScriptSig, ///Incorrect Script pubkey Hash for the descriptor. This is used for both /// `PkH` and `Wpkh` descriptors IncorrectPubkeyHash, ///Incorrect Script pubkey Hash for the descriptor. This is used for both /// `Sh` and `Wsh` descriptors IncorrectScriptHash, } #[doc(hidden)] impl<Pk> From<miniscript::types::Error<Pk>> for Error where Pk: MiniscriptKey, { fn from(e: miniscript::types::Error<Pk>) -> Error { Error::TypeCheck(e.to_string()) } } fn errstr(s: &str) -> Error { Error::Unexpected(s.to_owned()) } impl error::Error for Error { fn cause(&self) -> Option<&error::Error> { match *self { Error::BadPubkey(ref e) => Some(e), Error::Psbt(ref e) => Some(e), _ => None, } } fn description(&self) -> &str { "" } } impl fmt::Display for Error { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { Error::InvalidOpcode(op) => write!(f, "invalid opcode {}", op), Error::NonMinimalVerify(tok) => write!(f, "{} VERIFY", tok), Error::InvalidPush(ref push) => write!(f, "invalid push {:?}", push), // TODO hexify this Error::Psbt(ref e) => fmt::Display::fmt(e, f), Error::Script(ref e) => fmt::Display::fmt(e, f), Error::CmsTooManyKeys(n) => write!(f, "checkmultisig with {} keys", n), Error::Unprintable(x) => write!(f, "unprintable character 0x{:02x}", x), Error::ExpectedChar(c) => write!(f, "expected {}", c), Error::UnexpectedStart => f.write_str("unexpected start of script"), Error::Unexpected(ref s) => write!(f, "unexpected «{}»", s), Error::MultiColon(ref s) => write!(f, "«{}» has multiple instances of «:»", s), Error::MultiAt(ref s) => write!(f, "«{}» has multiple instances of «@»", s), Error::AtOutsideOr(ref s) => write!(f, "«{}» contains «@» in non-or() context", s), Error::NonCanonicalTrue => f.write_str("Use «t:X» rather than «and_v(X,true())»"), Error::NonCanonicalFalse => { f.write_str("Use «u:X» «l:X» rather than «or_i(X,false)» «or_i(false,X)»") } Error::LikelyFalse => write!(f, "0 is not very likely (use «u:0»)"), Error::UnknownWrapper(ch) => write!(f, "unknown wrapper «{}:»", ch), Error::NonTopLevel(ref s) => write!(f, "non-T miniscript: {}", s), Error::Trailing(ref s) => write!(f, "trailing tokens: {}", s), Error::MissingHash(ref h) => write!(f, "missing preimage of hash {}", h), Error::MissingSig(ref pk) => write!(f, "missing signature for key {:?}", pk), Error::RelativeLocktimeNotMet(n) => { write!(f, "required relative locktime CSV of {} blocks, not met", n) } Error::AbsoluteLocktimeNotMet(n) => write!( f, "required absolute locktime CLTV of {} blocks, not met", n ), Error::CouldNotSatisfy => f.write_str("could not satisfy"), Error::BadPubkey(ref e) => fmt::Display::fmt(e, f), Error::TypeCheck(ref e) => write!(f, "typecheck: {}", e), Error::BadDescriptor => f.write_str("could not create a descriptor"), Error::Secp(ref e) => fmt::Display::fmt(e, f), Error::InterpreterError(ref e) => fmt::Display::fmt(e, f), #[cfg(feature = "compiler")] Error::CompilerError(ref e) => fmt::Display::fmt(e, f), Error::BadScriptSig => f.write_str("Script sig must only consist of pushes"), Error::NonEmptyWitness => f.write_str("Non empty witness for Pk/Pkh"), Error::NonEmptyScriptSig => f.write_str("Non empty script sig for segwit spend"), Error::IncorrectScriptHash => { f.write_str("Incorrect script hash for redeem script sh/wsh") } Error::IncorrectPubkeyHash => { f.write_str("Incorrect pubkey hash for given descriptor pkh/wpkh") } } } } #[doc(hidden)] impl From<psbt::Error> for Error { fn from(e: psbt::Error) -> Error { Error::Psbt(e) } } #[doc(hidden)] #[cfg(feature = "compiler")] impl From<policy::compiler::CompilerError> for Error { fn from(e: policy::compiler::CompilerError) -> Error { Error::CompilerError(e) } } /// The size of an encoding of a number in Script pub fn script_num_size(n: usize) -> usize { match n { n if n <= 0x10 => 1, // OP_n n if n < 0x80 => 2, // OP_PUSH1 <n> n if n < 0x8000 => 3, // OP_PUSH2 <n> n if n < 0x800000 => 4, // OP_PUSH3 <n> n if n < 0x80000000 => 5, // OP_PUSH4 <n> _ => 6, // OP_PUSH5 <n> } } /// Helper function used by tests #[cfg(test)] fn hex_script(s: &str) -> bitcoin::Script { let v: Vec<u8> = bitcoin::hashes::hex::FromHex::from_hex(s).unwrap(); bitcoin::Script::from(v) }