diff --git a/src/descriptor/key_map.rs b/src/descriptor/key_map.rs new file mode 100644 index 000000000..0d989fb7f --- /dev/null +++ b/src/descriptor/key_map.rs @@ -0,0 +1,334 @@ +// SPDX-License-Identifier: CC0-1.0 + +//! A map of public key to secret key. + +use core::iter; + +use bitcoin::psbt::{GetKey, GetKeyError, KeyRequest}; +use bitcoin::secp256k1::{Secp256k1, Signing}; +use bitcoin::PrivateKey; + +#[cfg(doc)] +use super::Descriptor; +use super::{DescriptorKeyParseError, DescriptorPublicKey, DescriptorSecretKey}; +use crate::prelude::{btree_map, BTreeMap}; + +/// Alias type for a map of public key to secret key. +/// +/// This map is returned whenever a descriptor that contains secrets is parsed using +/// [`Descriptor::parse_descriptor`], since the descriptor will always only contain +/// public keys. This map allows looking up the corresponding secret key given a +/// public key from the descriptor. +#[derive(Debug, Clone, Eq, PartialEq)] +pub struct KeyMap { + map: BTreeMap, +} + +impl KeyMap { + /// Creates a new empty `KeyMap`. + #[inline] + pub fn new() -> Self { Self { map: BTreeMap::new() } } + + /// Inserts secret key into key map returning the associated public key. + #[inline] + pub fn insert( + &mut self, + secp: &Secp256k1, + sk: DescriptorSecretKey, + ) -> Result { + let pk = sk.to_public(secp)?; + if !self.map.contains_key(&pk) { + self.map.insert(pk.clone(), sk); + } + Ok(pk) + } + + /// Gets the secret key associated with `pk` if `pk` is in the map. + #[inline] + pub fn get(&self, pk: &DescriptorPublicKey) -> Option<&DescriptorSecretKey> { self.map.get(pk) } + + /// Returns the number of items in this map. + #[inline] + pub fn len(&self) -> usize { self.map.len() } + + /// Returns true if the map is empty. + #[inline] + pub fn is_empty(&self) -> bool { self.map.is_empty() } +} + +impl Default for KeyMap { + fn default() -> Self { Self::new() } +} + +impl IntoIterator for KeyMap { + type Item = (DescriptorPublicKey, DescriptorSecretKey); + type IntoIter = btree_map::IntoIter; + + #[inline] + fn into_iter(self) -> Self::IntoIter { self.map.into_iter() } +} + +impl iter::Extend<(DescriptorPublicKey, DescriptorSecretKey)> for KeyMap { + #[inline] + fn extend(&mut self, iter: T) + where + T: IntoIterator, + { + self.map.extend(iter) + } +} + +impl GetKey for KeyMap { + type Error = GetKeyError; + + fn get_key( + &self, + key_request: KeyRequest, + secp: &Secp256k1, + ) -> Result, Self::Error> { + Ok(self + .map + .iter() + .find_map(|(_desc_pk, desc_sk)| -> Option { + match desc_sk.get_key(key_request.clone(), secp) { + Ok(Some(pk)) => Some(pk), + Ok(None) | Err(_) => None, + } + })) + } +} + +impl GetKey for DescriptorSecretKey { + type Error = GetKeyError; + + fn get_key( + &self, + key_request: KeyRequest, + secp: &Secp256k1, + ) -> Result, Self::Error> { + match (self, key_request) { + (DescriptorSecretKey::Single(single_priv), key_request) => { + let sk = single_priv.key; + let pk = sk.public_key(secp); + let pubkey_map = BTreeMap::from([(pk, sk)]); + pubkey_map.get_key(key_request, secp) + } + (DescriptorSecretKey::XPrv(descriptor_xkey), KeyRequest::Pubkey(public_key)) => { + let xpriv = descriptor_xkey + .xkey + .derive_priv(secp, &descriptor_xkey.derivation_path) + .map_err(GetKeyError::Bip32)?; + let pk = xpriv.private_key.public_key(secp); + + if public_key.inner.eq(&pk) { + Ok(Some(xpriv.to_priv())) + } else { + Ok(None) + } + } + ( + DescriptorSecretKey::XPrv(descriptor_xkey), + ref key_request @ KeyRequest::Bip32(ref key_source), + ) => { + if let Some(key) = descriptor_xkey.xkey.get_key(key_request.clone(), secp)? { + return Ok(Some(key)); + } + + if let Some(_) = descriptor_xkey.matches(key_source, secp) { + let (_, derivation_path) = key_source; + return Ok(Some( + descriptor_xkey + .xkey + .derive_priv(secp, &derivation_path) + .map_err(GetKeyError::Bip32)? + .to_priv(), + )); + } + + Ok(None) + } + (DescriptorSecretKey::XPrv(_), KeyRequest::XOnlyPubkey(_)) => { + Err(GetKeyError::NotSupported) + } + ( + desc_multi_sk @ DescriptorSecretKey::MultiXPrv(_descriptor_multi_xkey), + key_request, + ) => Ok(desc_multi_sk.clone().into_single_keys().iter().find_map( + |desc_sk| match desc_sk.get_key(key_request.clone(), secp) { + Ok(Some(pk)) => Some(pk), + Ok(None) | Err(_) => None, + }, + )), + _ => unreachable!(), + } + } +} + +#[cfg(test)] +mod tests { + use core::str::FromStr; + + use bitcoin::bip32::{ChildNumber, DerivationPath, IntoDerivationPath, Xpriv}; + + use super::*; + use crate::Descriptor; + + #[test] + fn get_key_single_key() { + let secp = Secp256k1::new(); + + let descriptor_sk_s = + "[90b6a706/44'/0'/0'/0/0]cMk8gWmj1KpjdYnAWwsEDekodMYhbyYBhG8gMtCCxucJ98JzcNij"; + + let single = match descriptor_sk_s.parse::().unwrap() { + DescriptorSecretKey::Single(single) => single, + _ => panic!("unexpected DescriptorSecretKey variant"), + }; + + let want_sk = single.key; + let descriptor_s = format!("wpkh({})", descriptor_sk_s); + let (_, keymap) = Descriptor::parse_descriptor(&secp, &descriptor_s).unwrap(); + + let pk = want_sk.public_key(&secp); + let request = KeyRequest::Pubkey(pk); + let got_sk = keymap + .get_key(request, &secp) + .expect("get_key call errored") + .expect("failed to find the key"); + assert_eq!(got_sk, want_sk) + } + + #[test] + fn get_key_xpriv_single_key_xpriv() { + let secp = Secp256k1::new(); + + let s = "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi"; + + let xpriv = s.parse::().unwrap(); + let xpriv_fingerprint = xpriv.fingerprint(&secp); + + // Sanity check. + { + let descriptor_sk_s = format!("[{}]{}", xpriv_fingerprint, xpriv); + let descriptor_sk = descriptor_sk_s.parse::().unwrap(); + let got = match descriptor_sk { + DescriptorSecretKey::XPrv(x) => x.xkey, + _ => panic!("unexpected DescriptorSecretKey variant"), + }; + assert_eq!(got, xpriv); + } + + let want_sk = xpriv.to_priv(); + let descriptor_s = format!("wpkh([{}]{})", xpriv_fingerprint, xpriv); + let (_, keymap) = Descriptor::parse_descriptor(&secp, &descriptor_s).unwrap(); + + let pk = want_sk.public_key(&secp); + let request = KeyRequest::Pubkey(pk); + let got_sk = keymap + .get_key(request, &secp) + .expect("get_key call errored") + .expect("failed to find the key"); + assert_eq!(got_sk, want_sk) + } + + #[test] + fn get_key_xpriv_child_depth_one() { + let secp = Secp256k1::new(); + + let s = "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi"; + let master = s.parse::().unwrap(); + let master_fingerprint = master.fingerprint(&secp); + + let child_number = ChildNumber::from_hardened_idx(44).unwrap(); + let child = master.derive_priv(&secp, &[child_number]).unwrap(); + + // Sanity check. + { + let descriptor_sk_s = format!("[{}/44']{}", master_fingerprint, child); + let descriptor_sk = descriptor_sk_s.parse::().unwrap(); + let got = match descriptor_sk { + DescriptorSecretKey::XPrv(ref x) => x.xkey, + _ => panic!("unexpected DescriptorSecretKey variant"), + }; + assert_eq!(got, child); + } + + let want_sk = child.to_priv(); + let descriptor_s = format!("wpkh({}/44')", s); + let (_, keymap) = Descriptor::parse_descriptor(&secp, &descriptor_s).unwrap(); + + let pk = want_sk.public_key(&secp); + let request = KeyRequest::Pubkey(pk); + let got_sk = keymap + .get_key(request, &secp) + .expect("get_key call errored") + .expect("failed to find the key"); + assert_eq!(got_sk, want_sk) + } + + #[test] + fn get_key_xpriv_with_path() { + let secp = Secp256k1::new(); + + let s = "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi"; + let master = s.parse::().unwrap(); + let master_fingerprint = master.fingerprint(&secp); + + let first_external_child = "44'/0'/0'/0/0"; + let derivation_path = first_external_child.into_derivation_path().unwrap(); + + let child = master.derive_priv(&secp, &derivation_path).unwrap(); + + // Sanity check. + { + let descriptor_sk_s = + format!("[{}/{}]{}", master_fingerprint, first_external_child, child); + let descriptor_sk = descriptor_sk_s.parse::().unwrap(); + let got = match descriptor_sk { + DescriptorSecretKey::XPrv(ref x) => x.xkey, + _ => panic!("unexpected DescriptorSecretKey variant"), + }; + assert_eq!(got, child); + } + + let want_sk = child.to_priv(); + let descriptor_s = format!("wpkh({}/44'/0'/0'/0/*)", s); + let (_, keymap) = Descriptor::parse_descriptor(&secp, &descriptor_s).unwrap(); + + let key_source = (master_fingerprint, derivation_path); + let request = KeyRequest::Bip32(key_source); + let got_sk = keymap + .get_key(request, &secp) + .expect("get_key call errored") + .expect("failed to find the key"); + + assert_eq!(got_sk, want_sk) + } + + #[test] + fn get_key_xpriv_with_key_origin() { + let secp = Secp256k1::new(); + + let descriptor_str = "wpkh([d34db33f/84h/1h/0h]tprv8ZgxMBicQKsPd3EupYiPRhaMooHKUHJxNsTfYuScep13go8QFfHdtkG9nRkFGb7busX4isf6X9dURGCoKgitaApQ6MupRhZMcELAxTBRJgS/*)"; + let (_descriptor_pk, keymap) = Descriptor::parse_descriptor(&secp, descriptor_str).unwrap(); + + let descriptor_sk = DescriptorSecretKey::from_str("[d34db33f/84h/1h/0h]tprv8ZgxMBicQKsPd3EupYiPRhaMooHKUHJxNsTfYuScep13go8QFfHdtkG9nRkFGb7busX4isf6X9dURGCoKgitaApQ6MupRhZMcELAxTBRJgS/*").unwrap(); + let xpriv = match descriptor_sk { + DescriptorSecretKey::XPrv(descriptor_xkey) => descriptor_xkey, + _ => unreachable!(), + }; + + let path = DerivationPath::from_str("84'/1'/0'/0").unwrap(); + let expected_pk = xpriv.xkey.derive_priv(&secp, &path).unwrap().to_priv(); + + let (fp, _) = xpriv.origin.unwrap(); + let key_request = KeyRequest::Bip32((fp, path)); + + let pk = keymap + .get_key(key_request, &secp) + .expect("get_key should not fail") + .expect("get_key should return a `PrivateKey`"); + + assert_eq!(pk, expected_pk); + } +} diff --git a/src/descriptor/mod.rs b/src/descriptor/mod.rs index 44b93ce59..301fa2300 100644 --- a/src/descriptor/mod.rs +++ b/src/descriptor/mod.rs @@ -51,20 +51,14 @@ pub use self::tr::{ pub mod checksum; mod key; +mod key_map; pub use self::key::{ DefiniteDescriptorKey, DerivPaths, DescriptorKeyParseError, DescriptorMultiXKey, DescriptorPublicKey, DescriptorSecretKey, DescriptorXKey, InnerXKey, MalformedKeyDataKind, NonDefiniteKeyError, SinglePriv, SinglePub, SinglePubKey, Wildcard, XKeyNetwork, }; - -/// Alias type for a map of public key to secret key -/// -/// This map is returned whenever a descriptor that contains secrets is parsed using -/// [`Descriptor::parse_descriptor`], since the descriptor will always only contain -/// public keys. This map allows looking up the corresponding secret key given a -/// public key from the descriptor. -pub type KeyMap = BTreeMap; +pub use self::key_map::KeyMap; /// Script descriptor #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] @@ -725,28 +719,24 @@ impl Descriptor { key_map: &mut KeyMap, secp: &secp256k1::Secp256k1, ) -> Result { - let (public_key, secret_key) = match DescriptorSecretKey::from_str(s) { - Ok(sk) => ( - sk.to_public(secp) - .map_err(|e| Error::Unexpected(e.to_string()))?, - Some(sk), - ), - Err(_) => ( + match DescriptorSecretKey::from_str(s) { + Ok(sk) => { + let pk = key_map + .insert(secp, sk) + .map_err(|e| Error::Unexpected(e.to_string()))?; + Ok(pk) + } + Err(_) => { // try to parse as a public key if parsing as a secret key failed - s.parse() - .map_err(|e| Error::Parse(ParseError::box_from_str(e)))?, - None, - ), - }; - - if let Some(secret_key) = secret_key { - key_map.insert(public_key.clone(), secret_key); + let pk = s + .parse() + .map_err(|e| Error::Parse(ParseError::box_from_str(e)))?; + Ok(pk) + } } - - Ok(public_key) } - let mut keymap_pk = KeyMapWrapper(BTreeMap::new(), secp); + let mut keymap_pk = KeyMapWrapper(KeyMap::new(), secp); struct KeyMapWrapper<'a, C: secp256k1::Signing>(KeyMap, &'a secp256k1::Secp256k1); diff --git a/src/lib.rs b/src/lib.rs index 4d0e598a3..eac67c5d1 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -777,7 +777,7 @@ mod prelude { pub use alloc::{ borrow::{Borrow, Cow, ToOwned}, boxed::Box, - collections::{vec_deque::VecDeque, BTreeMap, BTreeSet, BinaryHeap}, + collections::{btree_map, vec_deque::VecDeque, BTreeMap, BTreeSet, BinaryHeap}, rc, slice, string::{String, ToString}, sync, @@ -787,7 +787,9 @@ mod prelude { pub use std::{ borrow::{Borrow, Cow, ToOwned}, boxed::Box, - collections::{vec_deque::VecDeque, BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet}, + collections::{ + btree_map, vec_deque::VecDeque, BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, + }, rc, slice, string::{String, ToString}, sync,