Add support for KeyExpr

Cargo.toml

@@ -12,7 +12,7 @@ edition = "2018"
 
 [features]
 default = ["std"]
-std = ["bitcoin/std", "bitcoin/secp-recovery"]
+std = ["bitcoin/std", "bitcoin/secp-recovery", "secp256k1-zkp"]
 no-std = ["hashbrown", "bitcoin/no-std"]
 compiler = []
 trace = []
@@ -24,6 +24,7 @@ rand = ["bitcoin/rand"]
 bitcoin = { version = "0.28.1", default-features = false }
 serde = { version = "1.0", optional = true }
 hashbrown = { version = "0.11", optional = true }
+secp256k1-zkp = { git = "https://github.com/sanket1729/rust-secp256k1-zkp", branch = "pr29", optional = true}
 
 [dev-dependencies]
 bitcoind = {version = "0.26.1", features=["22_0"]}

src/descriptor/mod.rs

@@ -34,6 +34,7 @@ use bitcoin::{self, secp256k1, Address, Network, Script, TxIn};
 use sync::Arc;
 
 use self::checksum::verify_checksum;
+use crate::miniscript::musig_key::KeyExpr;
 use crate::miniscript::{Legacy, Miniscript, Segwitv0};
 use crate::prelude::*;
 use crate::{
@@ -180,7 +181,7 @@ impl<Pk: MiniscriptKey> Descriptor<Pk> {
         // roundabout way to constuct `c:pk_k(pk)`
         let ms: Miniscript<Pk, BareCtx> =
             Miniscript::from_ast(miniscript::decode::Terminal::Check(Arc::new(
-                Miniscript::from_ast(miniscript::decode::Terminal::PkK(pk))
+                Miniscript::from_ast(miniscript::decode::Terminal::PkK(KeyExpr::SingleKey(pk)))
                     .expect("Type check cannot fail"),
             )))
             .expect("Type check cannot fail");

src/interpreter/mod.rs

@@ -593,6 +593,9 @@ where
                 Terminal::PkK(ref pk) => {
                     debug_assert_eq!(node_state.n_evaluated, 0);
                     debug_assert_eq!(node_state.n_satisfied, 0);
+                    let pk = pk
+                        .single_key()
+                        .expect("Musig keys cannot be parsed from Script");
                     let res = self.stack.evaluate_pk(&mut self.verify_sig, *pk);
                     if res.is_some() {
                         return res;
@@ -868,10 +871,11 @@ where
                         // evaluate each key with as a pk
                         // note that evaluate_pk will error on non-empty incorrect sigs
                         // push 1 on satisfied sigs and push 0 on empty sigs
-                        match self
-                            .stack
-                            .evaluate_pk(&mut self.verify_sig, subs[node_state.n_evaluated])
-                        {
+                        let pkk = subs[node_state.n_evaluated]
+                            .single_key()
+                            .expect("Musig keys cannot be parsed from Script");
+                        let res = self.stack.evaluate_pk(&mut self.verify_sig, *pkk);
+                        match res {
                             Some(Ok(x)) => {
                                 self.push_evaluation_state(
                                     node_state.node,

src/lib.rs

@@ -99,6 +99,9 @@ extern crate alloc;
 #[cfg(not(feature = "std"))]
 extern crate hashbrown;
 
+#[cfg(feature = "std")]
+extern crate secp256k1_zkp;
+
 #[cfg(any(feature = "std", test))]
 extern crate core;
 
@@ -775,6 +778,8 @@ pub enum Error {
     TrNoScriptCode,
     /// No explicit script for Tr descriptors
     TrNoExplicitScript,
+    /// Parsing error for single key
+    SingleKeyParseError,
 }
 
 // https://github.com/sipa/miniscript/pull/5 for discussion on this number
@@ -848,6 +853,7 @@ impl fmt::Display for Error {
             Error::TaprootSpendInfoUnavialable => write!(f, "Taproot Spend Info not computed."),
             Error::TrNoScriptCode => write!(f, "No script code for Tr descriptors"),
             Error::TrNoExplicitScript => write!(f, "No script code for Tr descriptors"),
+            Error::SingleKeyParseError => f.write_str("not able to parse the single key"),
         }
     }
 }
@@ -888,6 +894,7 @@ impl error::Error for Error {
             | BareDescriptorAddr
             | TaprootSpendInfoUnavialable
             | TrNoScriptCode
+            | SingleKeyParseError
             | TrNoExplicitScript => None,
             Script(e) => Some(e),
             AddrError(e) => Some(e),

src/miniscript/astelem.rs

@@ -26,6 +26,7 @@ use bitcoin::blockdata::{opcodes, script};
 use sync::Arc;
 
 use crate::miniscript::context::SigType;
+use crate::miniscript::musig_key::KeyExpr;
 use crate::miniscript::types::{self, Property};
 use crate::miniscript::ScriptContext;
 use crate::prelude::*;
@@ -80,7 +81,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
         Pk::RawPkHash: 'a,
     {
         match *self {
-            Terminal::PkK(ref p) => pred(p),
+            Terminal::PkK(ref p) => p.for_each_key(pred),
             Terminal::PkH(ref p) => pred(p),
             Terminal::RawPkH(..)
             | Terminal::After(..)
@@ -112,9 +113,8 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
                     && c.real_for_each_key(pred)
             }
             Terminal::Thresh(_, ref subs) => subs.iter().all(|sub| sub.real_for_each_key(pred)),
-            Terminal::Multi(_, ref keys) | Terminal::MultiA(_, ref keys) => {
-                keys.iter().all(|key| pred(key))
-            }
+            Terminal::Multi(_, ref keys) => keys.iter().all(|key| pred(key)),
+            Terminal::MultiA(_, ref keys) => keys.iter().all(|key| key.for_each_key(&mut *pred)),
         }
     }
 
@@ -125,7 +125,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
         T: Translator<Pk, Q, E>,
     {
         let frag: Terminal<Q, CtxQ> = match *self {
-            Terminal::PkK(ref p) => Terminal::PkK(t.pk(p)?),
+            Terminal::PkK(ref p) => Terminal::PkK(p.translate_pk(t)?),
             Terminal::PkH(ref p) => Terminal::PkH(t.pk(p)?),
             Terminal::RawPkH(ref p) => Terminal::RawPkH(t.pkh(p)?),
             Terminal::After(n) => Terminal::After(n),
@@ -186,7 +186,8 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
                 Terminal::Multi(k, keys?)
             }
             Terminal::MultiA(k, ref keys) => {
-                let keys: Result<Vec<Q>, _> = keys.iter().map(|k| t.pk(k)).collect();
+                let keys: Result<Vec<KeyExpr<Q>>, _> =
+                    keys.iter().map(|k| k.translate_pk(t)).collect();
                 Terminal::MultiA(k, keys?)
             }
         };
@@ -455,7 +456,7 @@ impl_from_tree!(
         }
         let mut unwrapped = match (frag_name, top.args.len()) {
             ("pk_k", 1) => {
-                expression::terminal(&top.args[0], |x| Pk::from_str(x).map(Terminal::PkK))
+                expression::unary(top, Terminal::PkK)
             }
             ("pk_h", 1) => expression::terminal(&top.args[0], |x| Pk::from_str(x).map(Terminal::PkH)),
             ("after", 1) => expression::terminal(&top.args[0], |x| {
@@ -522,15 +523,18 @@ impl_from_tree!(
                     return Err(errstr("higher threshold than there were keys in multi"));
                 }
 
-                let pks: Result<Vec<Pk>, _> = top.args[1..]
-                    .iter()
-                    .map(|sub| expression::terminal(sub, Pk::from_str))
-                    .collect();
-
                 if frag_name == "multi" {
+                    let pks: Result<Vec<Pk>, _> = top.args[1..]
+                        .iter()
+                        .map(|sub| expression::terminal(sub, Pk::from_str))
+                        .collect();
                     pks.map(|pks| Terminal::Multi(k, pks))
                 } else {
                     // must be multi_a
+                    let pks: Result<Vec<KeyExpr<Pk>>, _> = top.args[1..]
+                        .iter()
+                        .map(|sub| KeyExpr::<Pk>::from_tree(sub))
+                        .collect();
                     pks.map(|pks| Terminal::MultiA(k, pks))
                 }
             }
@@ -734,7 +738,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
                 builder = builder.push_ms_key::<_, Ctx>(&keys[0]);
                 builder = builder.push_opcode(opcodes::all::OP_CHECKSIG);
                 for pk in keys.iter().skip(1) {
-                    builder = builder.push_ms_key::<_, Ctx>(pk);
+                    builder = builder.push_ms_key::<_, Ctx>(&pk);
                     builder = builder.push_opcode(opcodes::all::OP_CHECKSIGADD);
                 }
                 builder
@@ -753,7 +757,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
     /// will handle the segwit/non-segwit technicalities for you.
     pub fn script_size(&self) -> usize {
         match *self {
-            Terminal::PkK(ref pk) => Ctx::pk_len(pk),
+            Terminal::PkK(ref pk) => Ctx::key_expr_len(pk),
             Terminal::PkH(..) | Terminal::RawPkH(..) => 24,
             Terminal::After(n) => script_num_size(n as usize) + 1,
             Terminal::Older(n) => script_num_size(n as usize) + 1,
@@ -798,7 +802,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Terminal<Pk, Ctx> {
             Terminal::MultiA(k, ref pks) => {
                 script_num_size(k)
                     + 1 // NUMEQUAL
-                    + pks.iter().map(|pk| Ctx::pk_len(pk)).sum::<usize>() // n keys
+                    + pks.iter().map(|pk| Ctx::key_expr_len(pk)).sum::<usize>() // n keys
                     + pks.len() // n times CHECKSIGADD
             }
         }

src/miniscript/context.rs

@@ -26,6 +26,7 @@ use crate::miniscript::limits::{
     MAX_SCRIPT_SIZE, MAX_STACK_SIZE, MAX_STANDARD_P2WSH_SCRIPT_SIZE,
     MAX_STANDARD_P2WSH_STACK_ITEMS,
 };
+use crate::miniscript::musig_key::KeyExpr;
 use crate::miniscript::types;
 use crate::prelude::*;
 use crate::util::witness_to_scriptsig;
@@ -77,6 +78,8 @@ pub enum ScriptContextError {
     CheckMultiSigLimitExceeded,
     /// MultiA is only allowed in post tapscript
     MultiANotAllowed,
+    /// Musig is only allowed in tapscript and taproot descriptors
+    MusigNotAllowed(String),
 }
 
 #[cfg(feature = "std")]
@@ -100,6 +103,7 @@ impl error::Error for ScriptContextError {
             | TaprootMultiDisabled
             | StackSizeLimitExceeded { .. }
             | CheckMultiSigLimitExceeded
+            | MusigNotAllowed(_)
             | MultiANotAllowed => None,
         }
     }
@@ -180,6 +184,9 @@ impl fmt::Display for ScriptContextError {
             ScriptContextError::MultiANotAllowed => {
                 write!(f, "Multi a(CHECKSIGADD) only allowed post tapscript")
             }
+            ScriptContextError::MusigNotAllowed(ref err) => {
+                write!(f, "Musig is only allowed in tapscript : err {}", err)
+            }
         }
     }
 }
@@ -334,6 +341,13 @@ where
     /// 34 for Segwitv0, 33 for Tap
     fn pk_len<Pk: MiniscriptKey>(pk: &Pk) -> usize;
 
+    /// Get the len of the keyexpr
+    fn key_expr_len<Pk: MiniscriptKey>(pk: &KeyExpr<Pk>) -> usize {
+        match pk {
+            KeyExpr::SingleKey(pk) => Self::pk_len(pk),
+            KeyExpr::MuSig(_) => 33,
+        }
+    }
     /// Local helper function to display error messages with context
     fn name_str() -> &'static str;
 }
@@ -384,12 +398,21 @@ impl ScriptContext for Legacy {
         }
 
         match ms.node {
-            Terminal::PkK(ref key) if key.is_x_only_key() => {
-                return Err(ScriptContextError::XOnlyKeysNotAllowed(
-                    key.to_string(),
-                    Self::name_str(),
-                ))
-            }
+            Terminal::PkK(ref key) => match key {
+                KeyExpr::<Pk>::SingleKey(pk) => {
+                    if pk.is_x_only_key() {
+                        return Err(ScriptContextError::XOnlyKeysNotAllowed(
+                            pk.to_string(),
+                            Self::name_str(),
+                        ));
+                    }
+                }
+                KeyExpr::<Pk>::MuSig(_) => {
+                    return Err(ScriptContextError::MusigNotAllowed(String::from(
+                        Self::name_str(),
+                    )))
+                }
+            },
             Terminal::Multi(_k, ref pks) => {
                 if pks.len() > MAX_PUBKEYS_PER_MULTISIG {
                     return Err(ScriptContextError::CheckMultiSigLimitExceeded);
@@ -490,17 +513,24 @@ impl ScriptContext for Segwitv0 {
         }
 
         match ms.node {
-            Terminal::PkK(ref pk) => {
-                if pk.is_uncompressed() {
-                    return Err(ScriptContextError::CompressedOnly(pk.to_string()));
-                } else if pk.is_x_only_key() {
-                    return Err(ScriptContextError::XOnlyKeysNotAllowed(
-                        pk.to_string(),
+            Terminal::PkK(ref key) => match key {
+                KeyExpr::<Pk>::SingleKey(pk) => {
+                    if pk.is_uncompressed() {
+                        return Err(ScriptContextError::CompressedOnly(pk.to_string()));
+                    } else if pk.is_x_only_key() {
+                        return Err(ScriptContextError::XOnlyKeysNotAllowed(
+                            pk.to_string(),
+                            Self::name_str(),
+                        ));
+                    }
+                    Ok(())
+                }
+                KeyExpr::<Pk>::MuSig(_) => {
+                    return Err(ScriptContextError::MusigNotAllowed(String::from(
                         Self::name_str(),
-                    ));
+                    )));
                 }
-                Ok(())
-            }
+            },
             Terminal::Multi(_k, ref pks) => {
                 if pks.len() > MAX_PUBKEYS_PER_MULTISIG {
                     return Err(ScriptContextError::CheckMultiSigLimitExceeded);
@@ -618,13 +648,24 @@ impl ScriptContext for Tap {
         }
 
         match ms.node {
-            Terminal::PkK(ref pk) => {
-                if pk.is_uncompressed() {
-                    return Err(ScriptContextError::UncompressedKeysNotAllowed);
+            Terminal::PkK(ref key) => {
+                if key.iter().any(|pk| pk.is_uncompressed()) {
+                    Err(ScriptContextError::UncompressedKeysNotAllowed)
+                } else {
+                    Ok(())
                 }
-                Ok(())
             }
             Terminal::Multi(..) => Err(ScriptContextError::TaprootMultiDisabled),
+            Terminal::MultiA(_, ref keys) => {
+                if keys
+                    .iter()
+                    .all(|keyexpr| keyexpr.iter().any(|pk| pk.is_uncompressed()))
+                {
+                    Err(ScriptContextError::UncompressedKeysNotAllowed)
+                } else {
+                    Ok(())
+                }
+            }
             _ => Ok(()),
         }
     }
@@ -712,11 +753,23 @@ impl ScriptContext for BareCtx {
             return Err(ScriptContextError::MaxWitnessScriptSizeExceeded);
         }
         match ms.node {
-            Terminal::PkK(ref key) if key.is_x_only_key() => {
-                return Err(ScriptContextError::XOnlyKeysNotAllowed(
-                    key.to_string(),
-                    Self::name_str(),
-                ))
+            Terminal::PkK(ref key) => {
+                match key {
+                    KeyExpr::<Pk>::SingleKey(pk) => {
+                        if pk.is_x_only_key() {
+                            return Err(ScriptContextError::XOnlyKeysNotAllowed(
+                                key.to_string(),
+                                Self::name_str(),
+                            ));
+                        }
+                    }
+                    KeyExpr::<Pk>::MuSig(_) => {
+                        return Err(ScriptContextError::MusigNotAllowed(String::from(
+                            Self::name_str(),
+                        )))
+                    }
+                }
+                Ok(())
             }
             Terminal::Multi(_k, ref pks) => {
                 if pks.len() > MAX_PUBKEYS_PER_MULTISIG {
@@ -753,7 +806,13 @@ impl ScriptContext for BareCtx {
         match &ms.node {
             Terminal::Check(ref ms) => match &ms.node {
                 Terminal::RawPkH(_pkh) => Ok(()),
-                Terminal::PkK(_pk) | Terminal::PkH(_pk) => Ok(()),
+                Terminal::PkH(_pk) => Ok(()),
+                Terminal::PkK(key) => match key {
+                    KeyExpr::<Pk>::SingleKey(_pk) => Ok(()),
+                    KeyExpr::<Pk>::MuSig(_) => Err(Error::ContextError(
+                        ScriptContextError::MusigNotAllowed(String::from(Self::name_str())),
+                    )),
+                },
                 _ => Err(Error::NonStandardBareScript),
             },
             Terminal::Multi(_k, subs) if subs.len() <= 3 => Ok(()),