1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144

// Miniscript
// Written in 2018 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/>.
//

//!  Script Policies
//!
//! Tools for representing Bitcoin scriptpubkeys as abstract spending policies.
//! These may be compiled to Miniscript, which contains extra information to
//! describe the exact representation as Bitcoin script.
//!
//! The format represents EC public keys abstractly to allow wallets to replace
//! these with BIP32 paths, pay-to-contract instructions, etc.
//!

#[cfg(feature = "compiler")]
pub mod compiler;
pub mod concrete;
pub mod semantic;

use descriptor::Descriptor;
use miniscript::Miniscript;
use Terminal;

pub use self::concrete::Policy as Concrete;
/// Semantic policies are "abstract" policies elsewhere; but we
/// avoid this word because it is a reserved keyword in Rust
pub use self::semantic::Policy as Semantic;
use MiniscriptKey;

/// Trait describing script representations which can be lifted into
/// an abstract policy, by discarding information.
/// After Lifting all policies are converted into `KeyHash(Pk::HasH)` to
/// maintain the following invariant:
/// `Lift(Concrete) == Concrete -> Miniscript -> Script -> Miniscript -> Semantic`
pub trait Liftable<Pk: MiniscriptKey> {
    /// Convert the object into an abstract policy
    fn lift(&self) -> Semantic<Pk>;
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Miniscript<Pk> {
    fn lift(&self) -> Semantic<Pk> {
        self.as_inner().lift()
    }
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Terminal<Pk> {
    fn lift(&self) -> Semantic<Pk> {
        match *self {
            Terminal::Pk(ref pk) => Semantic::KeyHash(pk.to_pubkeyhash()),
            Terminal::PkH(ref pkh) => Semantic::KeyHash(pkh.clone()),
            Terminal::After(t) => Semantic::After(t),
            Terminal::Older(t) => Semantic::Older(t),
            Terminal::Sha256(h) => Semantic::Sha256(h),
            Terminal::Hash256(h) => Semantic::Hash256(h),
            Terminal::Ripemd160(h) => Semantic::Ripemd160(h),
            Terminal::Hash160(h) => Semantic::Hash160(h),
            Terminal::True => Semantic::Trivial,
            Terminal::False => Semantic::Unsatisfiable,
            Terminal::Alt(ref sub)
            | Terminal::Swap(ref sub)
            | Terminal::Check(ref sub)
            | Terminal::DupIf(ref sub)
            | Terminal::Verify(ref sub)
            | Terminal::NonZero(ref sub)
            | Terminal::ZeroNotEqual(ref sub) => sub.node.lift(),
            Terminal::AndV(ref left, ref right) | Terminal::AndB(ref left, ref right) => {
                Semantic::And(vec![left.node.lift(), right.node.lift()])
            }
            Terminal::AndOr(ref a, ref b, ref c) => Semantic::Or(vec![
                Semantic::And(vec![a.node.lift(), c.node.lift()]),
                b.node.lift(),
            ]),
            Terminal::OrB(ref left, ref right)
            | Terminal::OrD(ref left, ref right)
            | Terminal::OrC(ref left, ref right)
            | Terminal::OrI(ref left, ref right) => {
                Semantic::Or(vec![left.node.lift(), right.node.lift()])
            }
            Terminal::Thresh(k, ref subs) => {
                Semantic::Threshold(k, subs.into_iter().map(|s| s.node.lift()).collect())
            }
            Terminal::ThreshM(k, ref keys) => Semantic::Threshold(
                k,
                keys.into_iter()
                    .map(|k| Semantic::KeyHash(k.to_pubkeyhash()))
                    .collect(),
            ),
        }
        .normalized()
    }
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Descriptor<Pk> {
    fn lift(&self) -> Semantic<Pk> {
        match *self {
            Descriptor::Bare(ref d)
            | Descriptor::Sh(ref d)
            | Descriptor::Wsh(ref d)
            | Descriptor::ShWsh(ref d) => d.node.lift(),
            Descriptor::Pk(ref p)
            | Descriptor::Pkh(ref p)
            | Descriptor::Wpkh(ref p)
            | Descriptor::ShWpkh(ref p) => Semantic::KeyHash(p.to_pubkeyhash()),
        }
    }
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Semantic<Pk> {
    fn lift(&self) -> Semantic<Pk> {
        self.clone()
    }
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Concrete<Pk> {
    fn lift(&self) -> Semantic<Pk> {
        match *self {
            Concrete::Key(ref pk) => Semantic::KeyHash(pk.to_pubkeyhash()),
            Concrete::After(t) => Semantic::After(t),
            Concrete::Older(t) => Semantic::Older(t),
            Concrete::Sha256(h) => Semantic::Sha256(h),
            Concrete::Hash256(h) => Semantic::Hash256(h),
            Concrete::Ripemd160(h) => Semantic::Ripemd160(h),
            Concrete::Hash160(h) => Semantic::Hash160(h),
            Concrete::And(ref subs) => Semantic::And(subs.iter().map(Liftable::lift).collect()),
            Concrete::Or(ref subs) => {
                Semantic::Or(subs.iter().map(|&(_, ref sub)| sub.lift()).collect())
            }
            Concrete::Threshold(k, ref subs) => {
                Semantic::Threshold(k, subs.iter().map(Liftable::lift).collect())
            }
        }
        .normalized()
    }
}