Merge #96: Pegin desc wildcard

624e3f4 create an address matching the fed desc (Riccardo Casatta)
59362c8 remove unused lint cfg causing warning (Riccardo Casatta)
2f1e07b Add Pegin::derived_descriptor (Riccardo Casatta)
f77617b Refactor out the fed peg desc in a function (Riccardo Casatta)
1a22725 Remove generic in Pegin descriptor for `fed_desc` (Riccardo Casatta)

Pull request description:

  On top of #95

  draft PR to investigate the derivability of a bunch of addresses from a pegin descriptor.

  Use the following assumption

  * federation descriptor is using only `bitcoin::PublicKey`

ACKs for top commit:
  apoelstra:
    ACK 624e3f4; successfully ran local tests

Tree-SHA512: 8861ff169aac8867c96c0950a2898b89f2a2aa35f3dff8ec11bc78f3d0cc2b6f0207a489637338f8df65b9c4ac5e947c1077a918d3aea3ffe1e70aebadcdbf7e

Author: apoelstra

Cargo.toml

@@ -35,9 +35,6 @@ bitcoin = { version = "0.32.0", features = ["base64"] }
 secp256k1 = { version = "0.29.0", features = ["rand-std"] }
 actual-base64 = { package = "base64", version = "0.13.0" }
 
-[lints.rust]
-unexpected_cfgs = { level = "deny", check-cfg = ['cfg(miniscript_bench)'] }
-
 [[example]]
 name = "htlc"
 required-features = ["compiler"]

src/descriptor/pegin/dynafed_pegin.rs

@@ -24,7 +24,8 @@ use std::convert::TryFrom;
 use std::fmt;
 
 use bitcoin::blockdata::script::{self, PushBytes};
-use bitcoin::{self, ScriptBuf as BtcScript, Weight};
+use bitcoin::{self, PublicKey, ScriptBuf as BtcScript, Weight};
+use bitcoin_miniscript::descriptor::DescriptorType;
 use elements::secp256k1_zkp;
 
 use crate::descriptor::checksum::{self, verify_checksum};
@@ -33,15 +34,15 @@ use crate::extensions::{CovExtArgs, CovenantExt};
 use crate::policy::{semantic, Liftable};
 use crate::{
     tweak_key, BtcDescriptor, BtcError, BtcFromTree, BtcLiftable, BtcPolicy, BtcSatisfier, BtcTree,
-    Descriptor, Error, MiniscriptKey, ToPublicKey,
+    Descriptor, DescriptorPublicKey, Error, MiniscriptKey, ToPublicKey,
 };
 
 /// New Pegin Descriptor with Miniscript support
 /// Useful with dynamic federations
 #[derive(Clone, Ord, PartialOrd, Eq, PartialEq)]
 pub struct Pegin<Pk: MiniscriptKey> {
     /// The untweaked pegin bitcoin descriptor
-    pub fed_desc: BtcDescriptor<Pk>,
+    pub fed_desc: BtcDescriptor<PublicKey>,
     /// The redeem elements descriptor
     ///
     /// TODO: Allow pegin redeem descriptor with extensions
@@ -51,7 +52,7 @@ pub struct Pegin<Pk: MiniscriptKey> {
 impl<Pk: MiniscriptKey> Pegin<Pk> {
     /// Create a new LegacyPegin descriptor
     pub fn new(
-        fed_desc: BtcDescriptor<Pk>,
+        fed_desc: BtcDescriptor<PublicKey>,
         elem_desc: Descriptor<Pk, CovenantExt<CovExtArgs>>,
     ) -> Self {
         Self {
@@ -61,6 +62,18 @@ impl<Pk: MiniscriptKey> Pegin<Pk> {
     }
 }
 
+impl Pegin<DescriptorPublicKey> {
+    pub fn derived_descriptor<C: secp256k1_zkp::Verification>(
+        &self,
+        arg: u32,
+        secp: &secp256k1_zkp::Secp256k1<C>,
+    ) -> Result<Pegin<PublicKey>, Error> {
+        let elem_desc = self.elem_desc.at_derivation_index(arg)?;
+        let elem_desc = elem_desc.derived_descriptor(&secp)?;
+        Ok(Pegin::new(self.fed_desc.clone(), elem_desc))
+    }
+}
+
 impl<Pk: MiniscriptKey> fmt::Debug for Pegin<Pk> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "pegin({:?},{:?})", self.fed_desc, self.elem_desc)
@@ -76,15 +89,15 @@ impl<Pk: MiniscriptKey> fmt::Display for Pegin<Pk> {
     }
 }
 
-impl<Pk: MiniscriptKey> Liftable<Pk> for Pegin<Pk> {
-    fn lift(&self) -> Result<semantic::Policy<Pk>, Error> {
+impl<Pk: MiniscriptKey> Liftable<PublicKey> for Pegin<Pk> {
+    fn lift(&self) -> Result<semantic::Policy<PublicKey>, Error> {
         let btc_pol = BtcLiftable::lift(&self.fed_desc)?;
         Liftable::lift(&btc_pol)
     }
 }
 
-impl<Pk: MiniscriptKey> BtcLiftable<Pk> for Pegin<Pk> {
-    fn lift(&self) -> Result<BtcPolicy<Pk>, BtcError> {
+impl<Pk: MiniscriptKey> BtcLiftable<PublicKey> for Pegin<Pk> {
+    fn lift(&self) -> Result<BtcPolicy<PublicKey>, BtcError> {
         self.fed_desc.lift()
     }
 }
@@ -101,7 +114,7 @@ impl_from_tree!(
             // TODO: Confirm with Andrew about the descriptor type for dynafed
             // Assuming sh(wsh) for now.
 
-            let fed_desc = BtcDescriptor::<Pk>::from_tree(&ms_expr)?;
+            let fed_desc = BtcDescriptor::<PublicKey>::from_tree(&ms_expr)?;
             let elem_desc = Descriptor::<Pk, CovenantExt<CovExtArgs>>::from_tree(&top.args[1])?;
             Ok(Pegin::new(fed_desc, elem_desc))
         } else {
@@ -146,13 +159,21 @@ impl<Pk: MiniscriptKey> Pegin<Pk> {
     where
         Pk: ToPublicKey,
     {
-        // TODO
-        Ok(bitcoin::Address::p2shwsh(
-            &self
-                .bitcoin_witness_script(secp)
-                .expect("DO this cleanly after TR. Pay to taproot pegins unspecified till now"),
-            network,
-        ))
+        match self.fed_desc.desc_type() {
+            DescriptorType::Wsh => Ok(bitcoin::Address::p2wsh(
+                &self
+                    .bitcoin_witness_script(secp)
+                    .expect("DO this cleanly after TR. Pay to taproot pegins unspecified till now"),
+                network,
+            )),
+            DescriptorType::ShWsh => Ok(bitcoin::Address::p2shwsh(
+                &self
+                    .bitcoin_witness_script(secp)
+                    .expect("DO this cleanly after TR. Pay to taproot pegins unspecified till now"),
+                network,
+            )),
+            _ => return Err(Error::UnsupportedAddressForPegin),
+        }
     }
 
     /// Computes the bitcoin scriptpubkey of the descriptor.
@@ -309,11 +330,23 @@ where
 
 #[cfg(test)]
 mod tests {
+    use bitcoin::PublicKey;
     use elements::hex::FromHex;
 
     use crate::descriptor::pegin::Pegin;
     use crate::{BtcDescriptor, ConfidentialDescriptor, DescriptorPublicKey};
 
+    fn fed_peg_desc() -> BtcDescriptor<PublicKey> {
+        let s = bitcoin::ScriptBuf::from_hex("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").unwrap();
+
+        type Segwitv0Script =
+            bitcoin_miniscript::Miniscript<bitcoin::PublicKey, bitcoin_miniscript::Segwitv0>;
+
+        let m = Segwitv0Script::parse(&s).unwrap();
+        assert_eq!(m.encode(), s);
+        BtcDescriptor::<_>::new_wsh(m).unwrap()
+    }
+
     // test vector created with:
     // ```
     // $ elements-cli getnetworkinfo | jq .version
@@ -330,16 +363,7 @@ mod tests {
     // ```
     #[test]
     fn test_pegin() {
-        let fedpegscript ="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";
-        let s = bitcoin::ScriptBuf::from_hex(fedpegscript).unwrap();
-
-        type Segwitv0Script =
-            bitcoin_miniscript::Miniscript<bitcoin::PublicKey, bitcoin_miniscript::Segwitv0>;
-
-        let m = Segwitv0Script::parse(&s).unwrap();
-        assert_eq!(m.encode(), s);
-
-        let d = BtcDescriptor::<_>::new_wsh(m).unwrap();
+        let d = fed_peg_desc();
 
         let fedpegdesc = "wsh(or_d(multi(11,020e0338c96a8870479f2396c373cc7696ba124e8635d41b0ea581112b67817261,02675333a4e4b8fb51d9d4e22fa5a8eaced3fdac8a8cbf9be8c030f75712e6af99,02896807d54bc55c24981f24a453c60ad3e8993d693732288068a23df3d9f50d48,029e51a5ef5db3137051de8323b001749932f2ff0d34c82e96a2c2461de96ae56c,02a4e1a9638d46923272c266631d94d36bdb03a64ee0e14c7518e49d2f29bc4010,031c41fdbcebe17bec8d49816e00ca1b5ac34766b91c9f2ac37d39c63e5e008afb,03079e252e85abffd3c401a69b087e590a9b86f33f574f08129ccbd3521ecf516b,03111cf405b627e22135b3b3733a4a34aa5723fb0f58379a16d32861bf576b0ec2,0318f331b3e5d38156da6633b31929c5b220349859cc9ca3d33fb4e68aa0840174,03230dae6b4ac93480aeab26d000841298e3b8f6157028e47b0897c1e025165de1,035abff4281ff00660f99ab27bb53e6b33689c2cd8dcd364bc3c90ca5aea0d71a6,03bd45cddfacf2083b14310ae4a84e25de61e451637346325222747b157446614c,03cc297026b06c71cbfa52089149157b5ff23de027ac5ab781800a578192d17546,03d3bde5d63bdb3a6379b461be64dad45eabff42f758543a9645afd42f6d424828,03ed1e8d5109c9ed66f7941bc53cc71137baa76d50d274bda8d5e8ffbd6e61fe9a),and_v(v:older(4032),multi(2,03aab896d53a8e7d6433137bbba940f9c521e085dd07e60994579b64a6d992cf79,0291b7d0b1b692f8f524516ed950872e5da10fb1b808b5a526dedc6fed1cf29807,0386aa9372fbab374593466bc5451dc59954e90787f08060964d95c87ef34ca5bb))))#7jwwklk4";
         assert_eq!(&d.to_string(), fedpegdesc);
@@ -362,4 +386,34 @@ mod tests {
 
         assert_eq!(pegin.to_string(), "pegin(wsh(or_d(multi(11,020e0338c96a8870479f2396c373cc7696ba124e8635d41b0ea581112b67817261,02675333a4e4b8fb51d9d4e22fa5a8eaced3fdac8a8cbf9be8c030f75712e6af99,02896807d54bc55c24981f24a453c60ad3e8993d693732288068a23df3d9f50d48,029e51a5ef5db3137051de8323b001749932f2ff0d34c82e96a2c2461de96ae56c,02a4e1a9638d46923272c266631d94d36bdb03a64ee0e14c7518e49d2f29bc4010,031c41fdbcebe17bec8d49816e00ca1b5ac34766b91c9f2ac37d39c63e5e008afb,03079e252e85abffd3c401a69b087e590a9b86f33f574f08129ccbd3521ecf516b,03111cf405b627e22135b3b3733a4a34aa5723fb0f58379a16d32861bf576b0ec2,0318f331b3e5d38156da6633b31929c5b220349859cc9ca3d33fb4e68aa0840174,03230dae6b4ac93480aeab26d000841298e3b8f6157028e47b0897c1e025165de1,035abff4281ff00660f99ab27bb53e6b33689c2cd8dcd364bc3c90ca5aea0d71a6,03bd45cddfacf2083b14310ae4a84e25de61e451637346325222747b157446614c,03cc297026b06c71cbfa52089149157b5ff23de027ac5ab781800a578192d17546,03d3bde5d63bdb3a6379b461be64dad45eabff42f758543a9645afd42f6d424828,03ed1e8d5109c9ed66f7941bc53cc71137baa76d50d274bda8d5e8ffbd6e61fe9a),and_v(v:older(4032),multi(2,03aab896d53a8e7d6433137bbba940f9c521e085dd07e60994579b64a6d992cf79,0291b7d0b1b692f8f524516ed950872e5da10fb1b808b5a526dedc6fed1cf29807,0386aa9372fbab374593466bc5451dc59954e90787f08060964d95c87ef34ca5bb)))),elwpkh(0321da398ca2ddc09be89caa26e6730ae84751b6ea3a1ca46aa365bb5e1c3d9620))#qp4fan9q");
     }
+
+    #[test]
+    fn test_pegin_derive() {
+        let elem_desc = "ct(slip77(ab5824f4477b4ebb00a132adfd8eb0b7935cf24f6ac151add5d1913db374ce92),elwpkh([759db348/84'/1'/0']tpubDCRMaF33e44pcJj534LXVhFbHibPbJ5vuLhSSPFAw57kYURv4tzXFL6LSnd78bkjqdmE3USedkbpXJUPA1tdzKfuYSL7PianceqAhwL2UkA/0/*))";
+        let elem_desc: ConfidentialDescriptor<DescriptorPublicKey> = elem_desc.parse().unwrap();
+        let fed_peg_desc = fed_peg_desc();
+        let pegin = Pegin::new(fed_peg_desc, elem_desc.descriptor);
+        let secp = secp256k1::Secp256k1::new();
+
+        let address_0 = pegin
+            .derived_descriptor(0, &secp)
+            .unwrap()
+            .bitcoin_address(bitcoin::Network::Bitcoin, &secp)
+            .unwrap();
+        assert_eq!(
+            address_0.to_string(),
+            "bc1qqkq6czql4zqwsylgrfzttjrn5wjeqmwfq5yn80p39amxtnkng9lsn6c5qr"
+        );
+
+        let address_1 = pegin
+            .derived_descriptor(1, &secp)
+            .unwrap()
+            .bitcoin_address(bitcoin::Network::Bitcoin, &secp)
+            .unwrap();
+        assert_ne!(address_0, address_1);
+        assert_eq!(
+            address_1.to_string(),
+            "bc1qmevs3n40t394230lptclz55rmxkmr7dmnqhuflxf0cezdupsmvdsk25n3m"
+        );
+    }
 }

src/lib.rs

@@ -373,6 +373,12 @@ pub enum Error {
     /// At least two BIP389 key expressions in the descriptor contain tuples of
     /// derivation indexes of different lengths.
     MultipathDescLenMismatch,
+
+    /// The federation descriptor has a type not supported
+    UnsupportedAddressForPegin,
+
+    /// Conversion error in descriptor
+    Conversion(descriptor::ConversionError),
 }
 
 #[doc(hidden)]
@@ -449,6 +455,12 @@ impl From<bitcoin::address::ParseError> for Error {
     }
 }
 
+impl From<descriptor::ConversionError> for Error {
+    fn from(e: descriptor::ConversionError) -> Error {
+        Error::Conversion(e)
+    }
+}
+
 fn errstr(s: &str) -> Error {
     Error::Unexpected(s.to_owned())
 }
@@ -530,6 +542,9 @@ impl fmt::Display for Error {
             Error::TrNoScriptCode => write!(f, "No script code for Tr descriptors"),
             Error::TrNoExplicitScript => write!(f, "No script code for Tr descriptors"),
             Error::MultipathDescLenMismatch => write!(f, "At least two BIP389 key expressions in the descriptor contain tuples of derivation indexes of different lengths"),
+            Error::Conversion(ref e) => e.fmt(f),
+            Error::UnsupportedAddressForPegin => write!(f, "Cannot create the address from the pegin descriptor, the federation descriptor is of an unsuppported type"),
+
         }
     }
 }
@@ -568,6 +583,7 @@ impl error::Error for Error {
             | BareDescriptorAddr
             | TaprootSpendInfoUnavialable
             | TrNoScriptCode
+            | UnsupportedAddressForPegin
             | TrNoExplicitScript => None,
             MultipathDescLenMismatch => None,
             BtcError(e) => Some(e),
@@ -584,6 +600,7 @@ impl error::Error for Error {
             ContextError(e) => Some(e),
             AnalysisError(e) => Some(e),
             PubKeyCtxError(e, _) => Some(e),
+            Conversion(e) => Some(e),
         }
     }
 }