Bump version to 0.18.0

9ed36875f1 export: Rename `WalletExport` to `FullyNodedExport` (Alekos Filini)

Pull request description:

  ### Description

  The `WalletExport` type can still be used as an alias to `FullyNodedExport` but it has been marked as deprecated and will be removed in the next release.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

  #### New Features:

  * [ ] I've added tests for the new feature
  * [x] I've added docs for the new feature
  * [x] I've updated `CHANGELOG.md`

ACKs for top commit:
  bucko13:
    Concept ACK 9ed3687
  notmandatory:
    ACK 9ed36875f1

Tree-SHA512: fe07307092d3040b30ae96901d5fc4afecee635412bca4a0d2e78d90f07990e7bbcd6b87ed923bf5804385356f419cacadbfefbaf97ebc9a622e34548438ee00

.github/workflows/cont_integration.yml

@@ -28,6 +28,7 @@ jobs:
           - async-interface
           - use-esplora-reqwest
           - sqlite
+          - sqlite-bundled
     steps:
       - name: checkout
         uses: actions/checkout@v2
@@ -114,7 +115,7 @@ jobs:
           override: true
       - name: Test
         run: cargo test --no-default-features --features ${{ matrix.blockchain.features }} ${{ matrix.blockchain.name }}::bdk_blockchain_tests
-  
+
   check-wasm:
     name: Check WASM
     runs-on: ubuntu-20.04

CHANGELOG.md

@@ -6,12 +6,25 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+
+
+## [v0.18.0] - [v0.17.0]
+
+- Add `sqlite-bundled` feature for deployments that need a bundled version of sqlite, ie. for mobile platforms.
+- Added `Wallet::get_signers()`, `Wallet::descriptor_checksum()` and `Wallet::get_address_validators()`, exposed the `AsDerived` trait.
+- Deprecate `database::Database::flush()`, the function is only needed for the sled database on mobile, instead for mobile use the sqlite database.
+- Add `keychain: KeychainKind` to `wallet::AddressInfo`.
+- Improve key generation traits
+- Rename `WalletExport` to `FullyNodedExport`, deprecate the former.
+- Bump `miniscript` dependency version to `^6.1`. 
+
 ## [v0.17.0] - [v0.16.1]
 
 - Removed default verification from `wallet::sync`. sync-time verification is added in `script_sync` and is activated by `verify` feature flag.
 - `verify` flag removed from `TransactionDetails`.
 - Add `get_internal_address` to allow you to get internal addresses just as you get external addresses.
 - added `ensure_addresses_cached` to `Wallet` to let offline wallets load and cache addresses in their database
+- Add `is_spent` field to `LocalUtxo`; when we notice that a utxo has been spent we set `is_spent` field to true instead of deleting it from the db.
 
 ### Sync API change
 
@@ -436,4 +449,5 @@ final transaction is created by calling `finish` on the builder.
 [v0.16.0]: https://github.com/bitcoindevkit/bdk/compare/v0.15.0...v0.16.0
 [v0.16.1]: https://github.com/bitcoindevkit/bdk/compare/v0.16.0...v0.16.1
 [v0.17.0]: https://github.com/bitcoindevkit/bdk/compare/v0.16.1...v0.17.0
-[unreleased]: https://github.com/bitcoindevkit/bdk/compare/v0.17.0...HEAD
+[v0.18.0]: https://github.com/bitcoindevkit/bdk/compare/v0.17.0...v0.18.0
+[unreleased]: https://github.com/bitcoindevkit/bdk/compare/v0.18.0...HEAD

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bdk"
-version = "0.17.0"
+version = "0.18.0"
 edition = "2018"
 authors = ["Alekos Filini <alekos.filini@gmail.com>", "Riccardo Casatta <riccardo@casatta.it>"]
 homepage = "https://bitcoindevkit.org"
@@ -14,7 +14,7 @@ license = "MIT OR Apache-2.0"
 [dependencies]
 bdk-macros = "^0.6"
 log = "^0.4"
-miniscript = { version = "^6.0", features = ["use-serde"] }
+miniscript = { version = "^6.1", features = ["use-serde"] }
 bitcoin = { version = "^0.27", features = ["use-serde", "base64"] }
 serde = { version = "^1.0", features = ["derive"] }
 serde_json = { version = "^1.0" }
@@ -55,6 +55,7 @@ compiler = ["miniscript/compiler"]
 verify = ["bitcoinconsensus"]
 default = ["key-value-db", "electrum"]
 sqlite = ["rusqlite", "ahash"]
+sqlite-bundled = ["sqlite", "rusqlite/bundled"]
 compact_filters = ["rocksdb", "socks", "lazy_static", "cc"]
 key-value-db = ["sled"]
 all-keys = ["keys-bip39"]
@@ -96,7 +97,7 @@ test-md-docs = ["electrum"]
 lazy_static = "1.4"
 env_logger = "0.7"
 clap = "2.33"
-electrsd = { version= "0.13", features = ["trigger", "bitcoind_22_0"] }
+electrsd = { version= "0.15", features = ["trigger", "bitcoind_22_0"] }
 
 [[example]]
 name = "address_validator"
@@ -109,6 +110,11 @@ name = "miniscriptc"
 path = "examples/compiler.rs"
 required-features = ["compiler"]
 
+[[example]]
+name = "rpcwallet"
+path = "examples/rpcwallet.rs"
+required-features = ["keys-bip39", "key-value-db", "rpc"]
+
 [workspace]
 members = ["macros"]
 [package.metadata.docs.rs]

examples/rpcwallet.rs

@@ -0,0 +1,229 @@
+// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+use bdk::bitcoin::secp256k1::Secp256k1;
+use bdk::bitcoin::Amount;
+use bdk::bitcoin::Network;
+use bdk::bitcoincore_rpc::RpcApi;
+
+use bdk::blockchain::rpc::{Auth, RpcBlockchain, RpcConfig};
+use bdk::blockchain::ConfigurableBlockchain;
+
+use bdk::keys::bip39::{Language, Mnemonic, WordCount};
+use bdk::keys::{DerivableKey, GeneratableKey, GeneratedKey};
+
+use bdk::miniscript::miniscript::Segwitv0;
+
+use bdk::sled;
+use bdk::template::Bip84;
+use bdk::wallet::{signer::SignOptions, wallet_name_from_descriptor, AddressIndex, SyncOptions};
+use bdk::KeychainKind;
+use bdk::Wallet;
+
+use bdk::blockchain::Blockchain;
+
+use electrsd;
+
+use std::error::Error;
+use std::path::PathBuf;
+use std::str::FromStr;
+
+/// This example demonstrates a typical way to create a wallet and work with bdk.
+///
+/// This example bdk wallet is connected to a bitcoin core rpc regtest node,
+/// and will attempt to receive, create and broadcast transactions.
+///
+/// To start a bitcoind regtest node programmatically, this example uses
+/// `electrsd` library, which is also a bdk dev-dependency.
+///
+/// But you can start your own bitcoind backend, and the rest of the example should work fine.
+
+fn main() -> Result<(), Box<dyn Error>> {
+    // -- Setting up background bitcoind process
+
+    println!(">> Setting up bitcoind");
+
+    // Start the bitcoind process
+    let bitcoind_conf = electrsd::bitcoind::Conf::default();
+
+    // electrsd will automatically download the bitcoin core binaries
+    let bitcoind_exe =
+        electrsd::bitcoind::downloaded_exe_path().expect("We should always have downloaded path");
+
+    // Launch bitcoind and gather authentication access
+    let bitcoind = electrsd::bitcoind::BitcoinD::with_conf(bitcoind_exe, &bitcoind_conf).unwrap();
+    let bitcoind_auth = Auth::Cookie {
+        file: bitcoind.params.cookie_file.clone(),
+    };
+
+    // Get a new core address
+    let core_address = bitcoind.client.get_new_address(None, None)?;
+
+    // Generate 101 blocks and use the above address as coinbase
+    bitcoind.client.generate_to_address(101, &core_address)?;
+
+    println!(">> bitcoind setup complete");
+    println!(
+        "Available coins in Core wallet : {}",
+        bitcoind.client.get_balance(None, None)?
+    );
+
+    // -- Setting up the Wallet
+
+    println!("\n>> Setting up BDK wallet");
+
+    // Get a random private key
+    let xprv = generate_random_ext_privkey()?;
+
+    // Use the derived descriptors from the privatekey to
+    // create unique wallet name.
+    // This is a special utility function exposed via `bdk::wallet_name_from_descriptor()`
+    let wallet_name = wallet_name_from_descriptor(
+        Bip84(xprv.clone(), KeychainKind::External),
+        Some(Bip84(xprv.clone(), KeychainKind::Internal)),
+        Network::Regtest,
+        &Secp256k1::new(),
+    )?;
+
+    // Create a database (using default sled type) to store wallet data
+    let mut datadir = PathBuf::from_str("/tmp/")?;
+    datadir.push(".bdk-example");
+    let database = sled::open(datadir)?;
+    let database = database.open_tree(wallet_name.clone())?;
+
+    // Create a RPC configuration of the running bitcoind backend we created in last step
+    // Note: If you are using custom regtest node, use the appropriate url and auth
+    let rpc_config = RpcConfig {
+        url: bitcoind.params.rpc_socket.to_string(),
+        auth: bitcoind_auth,
+        network: Network::Regtest,
+        wallet_name,
+        skip_blocks: None,
+    };
+
+    // Use the above configuration to create a RPC blockchain backend
+    let blockchain = RpcBlockchain::from_config(&rpc_config)?;
+
+    // Combine Database + Descriptor to create the final wallet
+    let wallet = Wallet::new(
+        Bip84(xprv.clone(), KeychainKind::External),
+        Some(Bip84(xprv.clone(), KeychainKind::Internal)),
+        Network::Regtest,
+        database,
+    )?;
+
+    // The `wallet` and the `blockchain` are independent structs.
+    // The wallet will be used to do all wallet level actions
+    // The blockchain can be used to do all blockchain level actions.
+    // For certain actions (like sync) the wallet will ask for a blockchain.
+
+    // Sync the wallet
+    // The first sync is important as this will instantiate the
+    // wallet files.
+    wallet.sync(&blockchain, SyncOptions::default())?;
+
+    println!(">> BDK wallet setup complete.");
+    println!(
+        "Available initial coins in BDK wallet : {} sats",
+        wallet.get_balance()?
+    );
+
+    // -- Wallet transaction demonstration
+
+    println!("\n>> Sending coins: Core --> BDK, 10 BTC");
+    // Get a new address to receive coins
+    let bdk_new_addr = wallet.get_address(AddressIndex::New)?.address;
+
+    // Send 10 BTC from core wallet to bdk wallet
+    bitcoind.client.send_to_address(
+        &bdk_new_addr,
+        Amount::from_btc(10.0)?,
+        None,
+        None,
+        None,
+        None,
+        None,
+        None,
+    )?;
+
+    // Confirm transaction by generating 1 block
+    bitcoind.client.generate_to_address(1, &core_address)?;
+
+    // Sync the BDK wallet
+    // This time the sync will fetch the new transaction and update it in
+    // wallet database
+    wallet.sync(&blockchain, SyncOptions::default())?;
+
+    println!(">> Received coins in BDK wallet");
+    println!(
+        "Available balance in BDK wallet: {} sats",
+        wallet.get_balance()?
+    );
+
+    println!("\n>> Sending coins: BDK --> Core, 5 BTC");
+    // Attempt to send back 5.0 BTC to core address by creating a transaction
+    //
+    // Transactions are created using a `TxBuilder`.
+    // This helps us to systematically build a transaction with all
+    // required customization.
+    // A full list of APIs offered by `TxBuilder` can be found at
+    // https://docs.rs/bdk/latest/bdk/wallet/tx_builder/struct.TxBuilder.html
+    let mut tx_builder = wallet.build_tx();
+
+    // For a regular transaction, just set the recipient and amount
+    tx_builder.set_recipients(vec![(core_address.script_pubkey(), 500000000)]);
+
+    // Finalize the transaction and extract the PSBT
+    let (mut psbt, _) = tx_builder.finish()?;
+
+    // Set signing option
+    let signopt = SignOptions {
+        assume_height: None,
+        ..Default::default()
+    };
+
+    // Sign the psbt
+    wallet.sign(&mut psbt, signopt)?;
+
+    // Extract the signed transaction
+    let tx = psbt.extract_tx();
+
+    // Broadcast the transaction
+    blockchain.broadcast(&tx)?;
+
+    // Confirm transaction by generating some blocks
+    bitcoind.client.generate_to_address(1, &core_address)?;
+
+    // Sync the BDK wallet
+    wallet.sync(&blockchain, SyncOptions::default())?;
+
+    println!(">> Coins sent to Core wallet");
+    println!(
+        "Remaining BDK wallet balance: {} sats",
+        wallet.get_balance()?
+    );
+    println!("\nCongrats!! you made your first test transaction with bdk and bitcoin core.");
+
+    Ok(())
+}
+
+// Helper function demonstrating privatekey extraction using bip39 mnemonic
+// The mnemonic can be shown to user to safekeeping and the same wallet
+// private descriptors can be recreated from it.
+fn generate_random_ext_privkey() -> Result<impl DerivableKey<Segwitv0> + Clone, Box<dyn Error>> {
+    // a Bip39 passphrase can be set optionally
+    let password = Some("random password".to_string());
+
+    // Generate a random mnemonic, and use that to create a "DerivableKey"
+    let mnemonic: GeneratedKey<_, _> = Mnemonic::generate((WordCount::Words12, Language::English))
+        .map_err(|e| e.expect("Unknown Error"))?;
+
+    // `Ok(mnemonic)` would also work if there's no passphrase and it would
+    // yield the same result as this construct with `password` = `None`.
+    Ok((mnemonic, password))
+}

src/blockchain/compact_filters/mod.rs

@@ -163,11 +163,19 @@ impl CompactFiltersBlockchain {
             if let Some(previous_output) = database.get_previous_output(&input.previous_output)? {
                 inputs_sum += previous_output.value;
 
-                if database.is_mine(&previous_output.script_pubkey)? {
+                // this output is ours, we have a path to derive it
+                if let Some((keychain, _)) =
+                    database.get_path_from_script_pubkey(&previous_output.script_pubkey)?
+                {
                     outgoing += previous_output.value;
 
-                    debug!("{} input #{} is mine, removing from utxo", tx.txid(), i);
+                    debug!("{} input #{} is mine, setting utxo as spent", tx.txid(), i);
-                    updates.del_utxo(&input.previous_output)?;
+                    updates.set_utxo(&LocalUtxo {
+                        outpoint: input.previous_output,
+                        txout: previous_output.clone(),
+                        keychain,
+                        is_spent: true,
+                    })?;
                 }
             }
         }
@@ -185,6 +193,7 @@ impl CompactFiltersBlockchain {
                     outpoint: OutPoint::new(tx.txid(), i as u32),
                     txout: output.clone(),
                     keychain,
+                    is_spent: false,
                 })?;
                 incoming += output.value;
 

src/blockchain/esplora/ureq.rs

@@ -127,10 +127,11 @@ impl WalletSync for EsploraBlockchain {
                         .take(self.concurrency as usize)
                         .cloned();
 
-                    let handles = scripts.map(move |script| {
+                    let mut handles = vec![];
+                    for script in scripts {
                         let client = self.url_client.clone();
                         // make each request in its own thread.
-                        std::thread::spawn(move || {
+                        handles.push(std::thread::spawn(move || {
                             let mut related_txs: Vec<Tx> = client._scripthash_txs(&script, None)?;
 
                             let n_confirmed =
@@ -152,10 +153,11 @@ impl WalletSync for EsploraBlockchain {
                                 }
                             }
                             Result::<_, Error>::Ok(related_txs)
-                        })
+                        }));
-                    });
+                    }
 
                     let txs_per_script: Vec<Vec<Tx>> = handles
+                        .into_iter()
                         .map(|handle| handle.join().unwrap())
                         .collect::<Result<_, _>>()?;
                     let mut satisfaction = vec![];

src/blockchain/rpc.rs

@@ -249,7 +249,7 @@ impl WalletSync for RpcBlockchain {
         let mut list_txs_ids = HashSet::new();
 
         for tx_result in list_txs.iter().filter(|t| {
-            // list_txs returns all conflicting tx we want to
+            // list_txs returns all conflicting txs, we want to
             // filter out replaced tx => unconfirmed and not in the mempool
             t.info.confirmations > 0 || self.client.get_mempool_entry(&t.info.txid).is_ok()
         }) {
@@ -332,20 +332,23 @@ impl WalletSync for RpcBlockchain {
                             value: u.amount.as_sat(),
                             script_pubkey: u.script_pub_key,
                         },
+                        is_spent: false,
                     })),
                 },
             )
             .collect::<Result<HashSet<_>, Error>>()?;
 
         let spent: HashSet<_> = known_utxos.difference(&current_utxos).collect();
-        for s in spent {
+        for utxo in spent {
-            debug!("removing utxo: {:?}", s);
+            debug!("setting as spent utxo: {:?}", utxo);
-            db.del_utxo(&s.outpoint)?;
+            let mut spent_utxo = utxo.clone();
+            spent_utxo.is_spent = true;
+            db.set_utxo(&spent_utxo)?;
         }
         let received: HashSet<_> = current_utxos.difference(&known_utxos).collect();
-        for s in received {
+        for utxo in received {
-            debug!("adding utxo: {:?}", s);
+            debug!("adding utxo: {:?}", utxo);
-            db.set_utxo(s)?;
+            db.set_utxo(utxo)?;
         }
 
         for (keykind, index) in indexes {

src/blockchain/script_sync.rs

@@ -332,7 +332,23 @@ impl<'a, D: BatchDatabase> State<'a, D> {
             batch.del_tx(txid, true)?;
         }
 
-        // Set every tx we observed
+        let mut spent_utxos = HashSet::new();
+
+        // track all the spent utxos
+        for finished_tx in &finished_txs {
+            let tx = finished_tx
+                .transaction
+                .as_ref()
+                .expect("transaction will always be present here");
+            for input in &tx.input {
+                spent_utxos.insert(&input.previous_output);
+            }
+        }
+
+        // set every utxo we observed, unless it's already spent
+        // we don't do this in the loop above as we want to know all the spent outputs before
+        // adding the non-spent to the batch in case there are new tranasactions
+        // that spend form each other.
         for finished_tx in &finished_txs {
             let tx = finished_tx
                 .transaction
@@ -343,30 +359,22 @@ impl<'a, D: BatchDatabase> State<'a, D> {
                     self.db.get_path_from_script_pubkey(&output.script_pubkey)?
                 {
                     // add utxos we own from the new transactions we've seen.
+                    let outpoint = OutPoint {
+                        txid: finished_tx.txid,
+                        vout: i as u32,
+                    };
+
                     batch.set_utxo(&LocalUtxo {
-                        outpoint: OutPoint {
+                        outpoint,
-                            txid: finished_tx.txid,
-                            vout: i as u32,
-                        },
                         txout: output.clone(),
                         keychain,
+                        // Is this UTXO in the spent_utxos set?
+                        is_spent: spent_utxos.get(&outpoint).is_some(),
                     })?;
                 }
             }
-            batch.set_tx(finished_tx)?;
-        }
 
-        // we don't do this in the loop above since we may want to delete some of the utxos we
+            batch.set_tx(finished_tx)?;
-        // just added in case there are new tranasactions that spend form each other.
-        for finished_tx in &finished_txs {
-            let tx = finished_tx
-                .transaction
-                .as_ref()
-                .expect("transaction will always be present here");
-            for input in &tx.input {
-                // Delete any spent utxos
-                batch.del_utxo(&input.previous_output)?;
-            }
         }
 
         for (keychain, last_active_index) in self.last_active_index {

src/database/any.rs

@@ -61,6 +61,7 @@ macro_rules! impl_from {
 
 macro_rules! impl_inner_method {
     ( $enum_name:ident, $self:expr, $name:ident $(, $args:expr)* ) => {
+        #[allow(deprecated)]
         match $self {
             $enum_name::Memory(inner) => inner.$name( $($args, )* ),
             #[cfg(feature = "key-value-db")]

src/database/keyvalue.rs

@@ -43,6 +43,7 @@ macro_rules! impl_batch_operations {
             let value = json!({
                 "t": utxo.txout,
                 "i": utxo.keychain,
+                "s": utxo.is_spent,
             });
             self.insert(key, serde_json::to_vec(&value)?)$($after_insert)*;
 
@@ -125,8 +126,9 @@ macro_rules! impl_batch_operations {
                     let mut val: serde_json::Value = serde_json::from_slice(&b)?;
                     let txout = serde_json::from_value(val["t"].take())?;
                     let keychain = serde_json::from_value(val["i"].take())?;
+                    let is_spent = val.get_mut("s").and_then(|s| s.take().as_bool()).unwrap_or(false);
 
-                    Ok(Some(LocalUtxo { outpoint: outpoint.clone(), txout, keychain }))
+                    Ok(Some(LocalUtxo { outpoint: outpoint.clone(), txout, keychain, is_spent, }))
                 }
             }
         }
@@ -246,11 +248,16 @@ impl Database for Tree {
                 let mut val: serde_json::Value = serde_json::from_slice(&v)?;
                 let txout = serde_json::from_value(val["t"].take())?;
                 let keychain = serde_json::from_value(val["i"].take())?;
+                let is_spent = val
+                    .get_mut("s")
+                    .and_then(|s| s.take().as_bool())
+                    .unwrap_or(false);
 
                 Ok(LocalUtxo {
                     outpoint,
                     txout,
                     keychain,
+                    is_spent,
                 })
             })
             .collect()
@@ -314,11 +321,16 @@ impl Database for Tree {
                 let mut val: serde_json::Value = serde_json::from_slice(&b)?;
                 let txout = serde_json::from_value(val["t"].take())?;
                 let keychain = serde_json::from_value(val["i"].take())?;
+                let is_spent = val
+                    .get_mut("s")
+                    .and_then(|s| s.take().as_bool())
+                    .unwrap_or(false);
 
                 Ok(LocalUtxo {
                     outpoint: *outpoint,
                     txout,
                     keychain,
+                    is_spent,
                 })
             })
             .transpose()

src/database/memory.rs

@@ -150,8 +150,10 @@ impl BatchOperations for MemoryDatabase {
 
     fn set_utxo(&mut self, utxo: &LocalUtxo) -> Result<(), Error> {
         let key = MapKey::Utxo(Some(&utxo.outpoint)).as_map_key();
-        self.map
+        self.map.insert(
-            .insert(key, Box::new((utxo.txout.clone(), utxo.keychain)));
+            key,
+            Box::new((utxo.txout.clone(), utxo.keychain, utxo.is_spent)),
+        );
 
         Ok(())
     }
@@ -228,11 +230,12 @@ impl BatchOperations for MemoryDatabase {
         match res {
             None => Ok(None),
             Some(b) => {
-                let (txout, keychain) = b.downcast_ref().cloned().unwrap();
+                let (txout, keychain, is_spent) = b.downcast_ref().cloned().unwrap();
                 Ok(Some(LocalUtxo {
                     outpoint: *outpoint,
                     txout,
                     keychain,
+                    is_spent,
                 }))
             }
         }
@@ -326,11 +329,12 @@ impl Database for MemoryDatabase {
             .range::<Vec<u8>, _>((Included(&key), Excluded(&after(&key))))
             .map(|(k, v)| {
                 let outpoint = deserialize(&k[1..]).unwrap();
-                let (txout, keychain) = v.downcast_ref().cloned().unwrap();
+                let (txout, keychain, is_spent) = v.downcast_ref().cloned().unwrap();
                 Ok(LocalUtxo {
                     outpoint,
                     txout,
                     keychain,
+                    is_spent,
                 })
             })
             .collect()
@@ -389,11 +393,12 @@ impl Database for MemoryDatabase {
     fn get_utxo(&self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error> {
         let key = MapKey::Utxo(Some(outpoint)).as_map_key();
         Ok(self.map.get(&key).map(|b| {
-            let (txout, keychain) = b.downcast_ref().cloned().unwrap();
+            let (txout, keychain, is_spent) = b.downcast_ref().cloned().unwrap();
             LocalUtxo {
                 outpoint: *outpoint,
                 txout,
                 keychain,
+                is_spent,
             }
         }))
     }
@@ -526,6 +531,7 @@ macro_rules! populate_test_db {
                     vout: vout as u32,
                 },
                 keychain: $crate::KeychainKind::External,
+                is_spent: false,
             })
             .unwrap();
         }

src/database/mod.rs

@@ -159,6 +159,10 @@ pub trait Database: BatchOperations {
     /// It should insert and return `0` if not present in the database
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error>;
 
+    #[deprecated(
+        since = "0.18.0",
+        note = "The flush function is only needed for the sled database on mobile, instead for mobile use the sqlite database."
+    )]
     /// Force changes to be written to disk
     fn flush(&mut self) -> Result<(), Error>;
 }
@@ -316,6 +320,7 @@ pub mod test {
             txout,
             outpoint,
             keychain: KeychainKind::External,
+            is_spent: true,
         };
 
         tree.set_utxo(&utxo).unwrap();

src/database/sqlite.rs

@@ -40,6 +40,7 @@ static MIGRATIONS: &[&str] = &[
     "CREATE TABLE transaction_details (txid BLOB, timestamp INTEGER, received INTEGER, sent INTEGER, fee INTEGER, height INTEGER);",
     "INSERT INTO transaction_details SELECT txid, timestamp, received, sent, fee, height FROM transaction_details_old;",
     "DROP TABLE transaction_details_old;",
+    "ALTER TABLE utxos ADD COLUMN is_spent;",
 ];
 
 /// Sqlite database stored on filesystem
@@ -83,14 +84,16 @@ impl SqliteDatabase {
         vout: u32,
         txid: &[u8],
         script: &[u8],
+        is_spent: bool,
     ) -> Result<i64, Error> {
-        let mut statement = self.connection.prepare_cached("INSERT INTO utxos (value, keychain, vout, txid, script) VALUES (:value, :keychain, :vout, :txid, :script)")?;
+        let mut statement = self.connection.prepare_cached("INSERT INTO utxos (value, keychain, vout, txid, script, is_spent) VALUES (:value, :keychain, :vout, :txid, :script, :is_spent)")?;
         statement.execute(named_params! {
             ":value": value,
             ":keychain": keychain,
             ":vout": vout,
             ":txid": txid,
-            ":script": script
+            ":script": script,
+            ":is_spent": is_spent,
         })?;
 
         Ok(self.connection.last_insert_rowid())
@@ -291,7 +294,7 @@ impl SqliteDatabase {
     fn select_utxos(&self) -> Result<Vec<LocalUtxo>, Error> {
         let mut statement = self
             .connection
-            .prepare_cached("SELECT value, keychain, vout, txid, script FROM utxos")?;
+            .prepare_cached("SELECT value, keychain, vout, txid, script, is_spent FROM utxos")?;
         let mut utxos: Vec<LocalUtxo> = vec![];
         let mut rows = statement.query([])?;
         while let Some(row) = rows.next()? {
@@ -300,6 +303,7 @@ impl SqliteDatabase {
             let vout = row.get(2)?;
             let txid: Vec<u8> = row.get(3)?;
             let script: Vec<u8> = row.get(4)?;
+            let is_spent: bool = row.get(5)?;
 
             let keychain: KeychainKind = serde_json::from_str(&keychain)?;
 
@@ -310,19 +314,16 @@ impl SqliteDatabase {
                     script_pubkey: script.into(),
                 },
                 keychain,
+                is_spent,
             })
         }
 
         Ok(utxos)
     }
 
-    fn select_utxo_by_outpoint(
+    fn select_utxo_by_outpoint(&self, txid: &[u8], vout: u32) -> Result<Option<LocalUtxo>, Error> {
-        &self,
-        txid: &[u8],
-        vout: u32,
-    ) -> Result<Option<(u64, KeychainKind, Script)>, Error> {
         let mut statement = self.connection.prepare_cached(
-            "SELECT value, keychain, script FROM utxos WHERE txid=:txid AND vout=:vout",
+            "SELECT value, keychain, script, is_spent FROM utxos WHERE txid=:txid AND vout=:vout",
         )?;
         let mut rows = statement.query(named_params! {":txid": txid,":vout": vout})?;
         match rows.next()? {
@@ -331,9 +332,18 @@ impl SqliteDatabase {
                 let keychain: String = row.get(1)?;
                 let keychain: KeychainKind = serde_json::from_str(&keychain)?;
                 let script: Vec<u8> = row.get(2)?;
-                let script: Script = script.into();
+                let script_pubkey: Script = script.into();
+                let is_spent: bool = row.get(3)?;
 
-                Ok(Some((value, keychain, script)))
+                Ok(Some(LocalUtxo {
+                    outpoint: OutPoint::new(deserialize(txid)?, vout),
+                    txout: TxOut {
+                        value,
+                        script_pubkey,
+                    },
+                    keychain,
+                    is_spent,
+                }))
             }
             None => Ok(None),
         }
@@ -620,6 +630,7 @@ impl BatchOperations for SqliteDatabase {
             utxo.outpoint.vout,
             &utxo.outpoint.txid,
             utxo.txout.script_pubkey.as_bytes(),
+            utxo.is_spent,
         )?;
         Ok(())
     }
@@ -694,16 +705,9 @@ impl BatchOperations for SqliteDatabase {
 
     fn del_utxo(&mut self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error> {
         match self.select_utxo_by_outpoint(&outpoint.txid, outpoint.vout)? {
-            Some((value, keychain, script_pubkey)) => {
+            Some(local_utxo) => {
                 self.delete_utxo_by_outpoint(&outpoint.txid, outpoint.vout)?;
-                Ok(Some(LocalUtxo {
+                Ok(Some(local_utxo))
-                    outpoint: *outpoint,
-                    txout: TxOut {
-                        value,
-                        script_pubkey,
-                    },
-                    keychain,
-                }))
             }
             None => Ok(None),
         }
@@ -832,17 +836,7 @@ impl Database for SqliteDatabase {
     }
 
     fn get_utxo(&self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error> {
-        match self.select_utxo_by_outpoint(&outpoint.txid, outpoint.vout)? {
+        self.select_utxo_by_outpoint(&outpoint.txid, outpoint.vout)
-            Some((value, keychain, script_pubkey)) => Ok(Some(LocalUtxo {
-                outpoint: *outpoint,
-                txout: TxOut {
-                    value,
-                    script_pubkey,
-                },
-                keychain,
-            })),
-            None => Ok(None),
-        }
     }
 
     fn get_raw_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {

src/descriptor/derived.rs

@@ -10,6 +10,41 @@
 // licenses.
 
 //! Derived descriptor keys
+//!
+//! The [`DerivedDescriptorKey`] type is a wrapper over the standard [`DescriptorPublicKey`] which
+//! guarantees that all the extended keys have a fixed derivation path, i.e. all the wildcards have
+//! been replaced by actual derivation indexes.
+//!
+//! The [`AsDerived`] trait provides a quick way to derive descriptors to obtain a
+//! `Descriptor<DerivedDescriptorKey>` type. This, in turn, can be used to derive public
+//! keys for arbitrary derivation indexes.
+//!
+//! Combining this with [`Wallet::get_signers`], secret keys can also be derived.
+//!
+//! # Example
+//!
+//! ```
+//! # use std::str::FromStr;
+//! # use bitcoin::secp256k1::Secp256k1;
+//! use bdk::descriptor::{AsDerived, DescriptorPublicKey};
+//! use bdk::miniscript::{ToPublicKey, TranslatePk, MiniscriptKey};
+//!
+//! let secp = Secp256k1::gen_new();
+//!
+//! let key = DescriptorPublicKey::from_str("[aa600a45/84'/0'/0']tpubDCbDXFKoLTQp44wQuC12JgSn5g9CWGjZdpBHeTqyypZ4VvgYjTJmK9CkyR5bFvG9f4PutvwmvpYCLkFx2rpx25hiMs4sUgxJveW8ZzSAVAc/0/*")?;
+//! let (descriptor, _, _) = bdk::descriptor!(wpkh(key))?;
+//!
+//! // derived: wpkh([aa600a45/84'/0'/0']tpubDCbDXFKoLTQp44wQuC12JgSn5g9CWGjZdpBHeTqyypZ4VvgYjTJmK9CkyR5bFvG9f4PutvwmvpYCLkFx2rpx25hiMs4sUgxJveW8ZzSAVAc/0/42)#3ladd0t2
+//! let derived = descriptor.as_derived(42, &secp);
+//! println!("derived: {}", derived);
+//!
+//! // with_pks: wpkh(02373ecb54c5e83bd7e0d40adf78b65efaf12fafb13571f0261fc90364eee22e1e)#p4jjgvll
+//! let with_pks = derived.translate_pk_infallible(|pk| pk.to_public_key(), |pkh| pkh.to_public_key().to_pubkeyhash());
+//! println!("with_pks: {}", with_pks);
+//! # Ok::<(), Box<dyn std::error::Error>>(())
+//! ```
+//!
+//! [`Wallet::get_signers`]: crate::wallet::Wallet::get_signers
 
 use std::cmp::Ordering;
 use std::fmt;
@@ -19,10 +54,7 @@ use std::ops::Deref;
 use bitcoin::hashes::hash160;
 use bitcoin::PublicKey;
 
-pub use miniscript::{
+use miniscript::{descriptor::Wildcard, Descriptor, DescriptorPublicKey};
-    descriptor::KeyMap, descriptor::Wildcard, Descriptor, DescriptorPublicKey, Legacy, Miniscript,
-    ScriptContext, Segwitv0,
-};
 use miniscript::{MiniscriptKey, ToPublicKey, TranslatePk};
 
 use crate::wallet::utils::SecpCtx;
@@ -119,14 +151,19 @@ impl<'s> ToPublicKey for DerivedDescriptorKey<'s> {
     }
 }
 
-pub(crate) trait AsDerived {
+/// Utilities to derive descriptors
-    // Derive a descriptor and transform all of its keys to `DerivedDescriptorKey`
+///
+/// Check out the [module level] documentation for more.
+///
+/// [module level]: crate::descriptor::derived
+pub trait AsDerived {
+    /// Derive a descriptor and transform all of its keys to `DerivedDescriptorKey`
     fn as_derived<'s>(&self, index: u32, secp: &'s SecpCtx)
         -> Descriptor<DerivedDescriptorKey<'s>>;
 
-    // Transform the keys into `DerivedDescriptorKey`.
+    /// Transform the keys into `DerivedDescriptorKey`.
-    //
+    ///
-    // Panics if the descriptor is not "fixed", i.e. if it's derivable
+    /// Panics if the descriptor is not "fixed", i.e. if it's derivable
     fn as_derived_fixed<'s>(&self, secp: &'s SecpCtx) -> Descriptor<DerivedDescriptorKey<'s>>;
 }
 

src/descriptor/dsl.rs

@@ -336,7 +336,7 @@ macro_rules! apply_modifier {
 /// syntax is more suitable for a fixed number of items known at compile time, while the other accepts a
 /// [`Vec`] of items, which makes it more suitable for writing dynamic descriptors.
 ///
-/// They both produce the descriptor: `wsh(thresh(2,pk(...),s:pk(...),sdv:older(...)))`
+/// They both produce the descriptor: `wsh(thresh(2,pk(...),s:pk(...),sndv:older(...)))`
 ///
 /// ```
 /// # use std::str::FromStr;
@@ -349,7 +349,7 @@ macro_rules! apply_modifier {
 ///
 /// let (descriptor_a, key_map_a, networks) = bdk::descriptor! {
 ///     wsh (
-///         thresh(2, pk(my_key_1), s:pk(my_key_2), s:d:v:older(my_timelock))
+///         thresh(2, pk(my_key_1), s:pk(my_key_2), s:n:d:v:older(my_timelock))
 ///     )
 /// }?;
 ///
@@ -357,7 +357,7 @@ macro_rules! apply_modifier {
 /// let b_items = vec![
 ///     bdk::fragment!(pk(my_key_1))?,
 ///     bdk::fragment!(s:pk(my_key_2))?,
-///     bdk::fragment!(s:d:v:older(my_timelock))?,
+///     bdk::fragment!(s:n:d:v:older(my_timelock))?,
 /// ];
 /// let (descriptor_b, mut key_map_b, networks) = bdk::descriptor!(wsh(thresh_vec(2, b_items)))?;
 ///
@@ -1048,9 +1048,9 @@ mod test {
         let private_key =
             PrivateKey::from_wif("cSQPHDBwXGjVzWRqAHm6zfvQhaTuj1f2bFH58h55ghbjtFwvmeXR").unwrap();
         let (descriptor, _, _) =
-            descriptor!(wsh(thresh(2,d:v:older(1),s:pk(private_key),s:pk(private_key)))).unwrap();
+            descriptor!(wsh(thresh(2,n:d:v:older(1),s:pk(private_key),s:pk(private_key)))).unwrap();
 
-        assert_eq!(descriptor.to_string(), "wsh(thresh(2,dv:older(1),s:pk(02e96fe52ef0e22d2f131dd425ce1893073a3c6ad20e8cac36726393dfb4856a4c),s:pk(02e96fe52ef0e22d2f131dd425ce1893073a3c6ad20e8cac36726393dfb4856a4c)))#cfdcqs3s")
+        assert_eq!(descriptor.to_string(), "wsh(thresh(2,ndv:older(1),s:pk(02e96fe52ef0e22d2f131dd425ce1893073a3c6ad20e8cac36726393dfb4856a4c),s:pk(02e96fe52ef0e22d2f131dd425ce1893073a3c6ad20e8cac36726393dfb4856a4c)))#zzk3ux8g")
     }
 
     #[test]

src/descriptor/mod.rs

@@ -21,16 +21,17 @@ use bitcoin::util::bip32::{ChildNumber, DerivationPath, ExtendedPubKey, Fingerpr
 use bitcoin::util::psbt;
 use bitcoin::{Network, PublicKey, Script, TxOut};
 
-use miniscript::descriptor::{
+use miniscript::descriptor::{DescriptorType, InnerXKey};
-    DescriptorPublicKey, DescriptorType, DescriptorXKey, InnerXKey, Wildcard,
+pub use miniscript::{
+    descriptor::DescriptorXKey, descriptor::KeyMap, descriptor::Wildcard, Descriptor,
+    DescriptorPublicKey, Legacy, Miniscript, ScriptContext, Segwitv0,
 };
-pub use miniscript::{descriptor::KeyMap, Descriptor, Legacy, Miniscript, ScriptContext, Segwitv0};
 use miniscript::{DescriptorTrait, ForEachKey, TranslatePk};
 
 use crate::descriptor::policy::BuildSatisfaction;
 
 pub mod checksum;
-pub(crate) mod derived;
+pub mod derived;
 #[doc(hidden)]
 pub mod dsl;
 pub mod error;
@@ -38,8 +39,7 @@ pub mod policy;
 pub mod template;
 
 pub use self::checksum::get_checksum;
-use self::derived::AsDerived;
+pub use self::derived::{AsDerived, DerivedDescriptorKey};
-pub use self::derived::DerivedDescriptorKey;
 pub use self::error::Error as DescriptorError;
 pub use self::policy::Policy;
 use self::template::DescriptorTemplateOut;

src/descriptor/policy.rs

@@ -1501,7 +1501,7 @@ mod test {
         let (prvkey_bob, _, _) = setup_keys(BOB_TPRV_STR, ALICE_BOB_PATH, &secp);
 
         let desc =
-            descriptor!(wsh(thresh(2,d:v:older(2),s:pk(prvkey_alice),s:pk(prvkey_bob)))).unwrap();
+            descriptor!(wsh(thresh(2,n:d:v:older(2),s:pk(prvkey_alice),s:pk(prvkey_bob)))).unwrap();
 
         let (wallet_desc, keymap) = desc
             .into_wallet_descriptor(&secp, Network::Testnet)
@@ -1513,7 +1513,7 @@ mod test {
             .address(Network::Testnet)
             .unwrap();
         assert_eq!(
-            "tb1qhpemaacpeu8ajlnh8k9v55ftg0px58r8630fz8t5mypxcwdk5d8sum522g",
+            "tb1qsydsey4hexagwkvercqsmes6yet0ndkyt6uzcphtqnygjd8hmzmsfxrv58",
             addr.to_string()
         );
 

src/keys/bip39.rs

@@ -94,6 +94,23 @@ impl<Ctx: ScriptContext> DerivableKey<Ctx> for MnemonicWithPassphrase {
     }
 }
 
+#[cfg_attr(docsrs, doc(cfg(feature = "keys-bip39")))]
+impl<Ctx: ScriptContext> DerivableKey<Ctx> for (GeneratedKey<Mnemonic, Ctx>, Option<String>) {
+    fn into_extended_key(self) -> Result<ExtendedKey<Ctx>, KeyError> {
+        let (mnemonic, passphrase) = self;
+        (mnemonic.into_key(), passphrase).into_extended_key()
+    }
+
+    fn into_descriptor_key(
+        self,
+        source: Option<bip32::KeySource>,
+        derivation_path: bip32::DerivationPath,
+    ) -> Result<DescriptorKey<Ctx>, KeyError> {
+        let (mnemonic, passphrase) = self;
+        (mnemonic.into_key(), passphrase).into_descriptor_key(source, derivation_path)
+    }
+}
+
 #[cfg_attr(docsrs, doc(cfg(feature = "keys-bip39")))]
 impl<Ctx: ScriptContext> DerivableKey<Ctx> for Mnemonic {
     fn into_extended_key(self) -> Result<ExtendedKey<Ctx>, KeyError> {

src/keys/mod.rs

@@ -548,6 +548,16 @@ impl<K, Ctx: ScriptContext> Deref for GeneratedKey<K, Ctx> {
     }
 }
 
+impl<K: Clone, Ctx: ScriptContext> Clone for GeneratedKey<K, Ctx> {
+    fn clone(&self) -> GeneratedKey<K, Ctx> {
+        GeneratedKey {
+            key: self.key.clone(),
+            valid_networks: self.valid_networks.clone(),
+            phantom: self.phantom,
+        }
+    }
+}
+
 // Make generated "derivable" keys themselves "derivable". Also make sure they are assigned the
 // right `valid_networks`.
 impl<Ctx, K> DerivableKey<Ctx> for GeneratedKey<K, Ctx>

src/lib.rs

@@ -44,14 +44,15 @@
 //! interact with the bitcoin P2P network.
 //!
 //! ```toml
-//! bdk = "0.17.0"
+//! bdk = "0.18.0"
 //! ```
+//!
+//! # Examples
 #![cfg_attr(
     feature = "electrum",
     doc = r##"
 ## Sync the balance of a descriptor
 
-### Example
 ```no_run
 use bdk::{Wallet, SyncOptions};
 use bdk::database::MemoryDatabase;
@@ -80,7 +81,6 @@ fn main() -> Result<(), bdk::Error> {
 //!
 //! ## Generate a few addresses
 //!
-//! ### Example
 //! ```
 //! use bdk::{Wallet};
 //! use bdk::database::MemoryDatabase;
@@ -106,7 +106,6 @@ fn main() -> Result<(), bdk::Error> {
     doc = r##"
 ## Create a transaction
 
-### Example
 ```no_run
 use bdk::{FeeRate, Wallet, SyncOptions};
 use bdk::database::MemoryDatabase;
@@ -150,7 +149,6 @@ fn main() -> Result<(), bdk::Error> {
 //!
 //! ## Sign a transaction
 //!
-//! ### Example
 //! ```no_run
 //! use std::str::FromStr;
 //!
@@ -192,7 +190,7 @@ fn main() -> Result<(), bdk::Error> {
 //! * `async-interface`: async functions in bdk traits
 //! * `keys-bip39`: [BIP-39](https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki) mnemonic codes for generating deterministic keys
 //!
-//! ## Internal features
+//! # Internal features
 //!
 //! These features do not expose any new API, but influence internal implementation aspects of
 //! BDK.

src/testutils/blockchain_tests.rs

@@ -320,7 +320,7 @@ impl Default for TestClient {
     fn default() -> Self {
         let bitcoind_exe = env::var("BITCOIND_EXE")
             .ok()
-            .or(bitcoind::downloaded_exe_path())
+            .or(bitcoind::downloaded_exe_path().ok())
             .expect(
                 "you should provide env var BITCOIND_EXE or specifiy a bitcoind version feature",
             );
@@ -1125,6 +1125,47 @@ macro_rules! bdk_blockchain_tests {
                 assert_eq!(tx_2.sent, 0);
             }
 
+            #[test]
+            fn test_double_spend() {
+                // We create a tx and then we try to double spend it; BDK will always allow
+                // us to do so, as it never forgets about spent UTXOs
+                let (wallet, blockchain, descriptors, mut test_client) = init_single_sig();
+                let node_addr = test_client.get_node_address(None);
+                let _ = test_client.receive(testutils! {
+                    @tx ( (@external descriptors, 0) => 50_000 )
+                });
+
+                wallet.sync(&blockchain, SyncOptions::default()).unwrap();
+                let mut builder = wallet.build_tx();
+                builder.add_recipient(node_addr.script_pubkey(), 25_000);
+                let (mut psbt, _details) = builder.finish().unwrap();
+                let finalized = wallet.sign(&mut psbt, Default::default()).unwrap();
+                assert!(finalized, "Cannot finalize transaction");
+                let initial_tx = psbt.extract_tx();
+                let _sent_txid = blockchain.broadcast(&initial_tx).unwrap();
+                wallet.sync(&blockchain, SyncOptions::default()).unwrap();
+                for utxo in wallet.list_unspent().unwrap() {
+                    // Making sure the TXO we just spent is not returned by list_unspent
+                    assert!(utxo.outpoint != initial_tx.input[0].previous_output, "wallet displays spent txo in unspents");
+                }
+                // We can still create a transaction double spending `initial_tx`
+                let mut builder = wallet.build_tx();
+                builder
+                    .add_utxo(initial_tx.input[0].previous_output)
+                    .expect("Can't manually add an UTXO spent");
+                test_client.generate(1, Some(node_addr));
+                wallet.sync(&blockchain, SyncOptions::default()).unwrap();
+                // Even after confirmation, we can still create a tx double spend it
+                let mut builder = wallet.build_tx();
+                builder
+                    .add_utxo(initial_tx.input[0].previous_output)
+                    .expect("Can't manually add an UTXO spent");
+                for utxo in wallet.list_unspent().unwrap() {
+                    // Making sure the TXO we just spent is not returned by list_unspent
+                    assert!(utxo.outpoint != initial_tx.input[0].previous_output, "wallet displays spent txo in unspents");
+                }
+            }
+
             #[test]
             fn test_send_receive_pkh() {
                 let descriptors = ("pkh(cVpPVruEDdmutPzisEsYvtST1usBR3ntr8pXSyt6D2YYqXRyPcFW)".to_string(), None);

src/types.rs

@@ -131,6 +131,8 @@ pub struct LocalUtxo {
     pub txout: TxOut,
     /// Type of keychain
     pub keychain: KeychainKind,
+    /// Whether this UTXO is spent or not
+    pub is_spent: bool,
 }
 
 /// A [`Utxo`] with its `satisfaction_weight`.

src/wallet/coin_selection.rs

@@ -569,6 +569,7 @@ mod test {
                     script_pubkey: Script::new(),
                 },
                 keychain: KeychainKind::External,
+                is_spent: false,
             }),
         }
     }
@@ -596,6 +597,7 @@ mod test {
                         script_pubkey: Script::new(),
                     },
                     keychain: KeychainKind::External,
+                    is_spent: false,
                 }),
             });
         }
@@ -615,6 +617,7 @@ mod test {
                     script_pubkey: Script::new(),
                 },
                 keychain: KeychainKind::External,
+                is_spent: false,
             }),
         };
         vec![utxo; utxos_number]

src/wallet/export.rs

@@ -29,7 +29,7 @@
 //!     "label":"testnet"
 //! }"#;
 //!
-//! let import = WalletExport::from_str(import)?;
+//! let import = FullyNodedExport::from_str(import)?;
 //! let wallet = Wallet::new(
 //!     &import.descriptor(),
 //!     import.change_descriptor().as_ref(),
@@ -51,7 +51,7 @@
 //!     Network::Testnet,
 //!     MemoryDatabase::default()
 //! )?;
-//! let export = WalletExport::export_wallet(&wallet, "exported wallet", true)
+//! let export = FullyNodedExport::export_wallet(&wallet, "exported wallet", true)
 //!     .map_err(ToString::to_string)
 //!     .map_err(bdk::Error::Generic)?;
 //!
@@ -64,16 +64,21 @@ use std::str::FromStr;
 use serde::{Deserialize, Serialize};
 
 use miniscript::descriptor::{ShInner, WshInner};
-use miniscript::{Descriptor, DescriptorPublicKey, ScriptContext, Terminal};
+use miniscript::{Descriptor, ScriptContext, Terminal};
 
 use crate::database::BatchDatabase;
+use crate::types::KeychainKind;
 use crate::wallet::Wallet;
 
+/// Alias for [`FullyNodedExport`]
+#[deprecated(since = "0.18.0", note = "Please use [`FullyNodedExport`] instead")]
+pub type WalletExport = FullyNodedExport;
+
 /// Structure that contains the export of a wallet
 ///
 /// For a usage example see [this module](crate::wallet::export)'s documentation.
 #[derive(Debug, Serialize, Deserialize)]
-pub struct WalletExport {
+pub struct FullyNodedExport {
     descriptor: String,
     /// Earliest block to rescan when looking for the wallet's transactions
     pub blockheight: u32,
@@ -81,13 +86,13 @@ pub struct WalletExport {
     pub label: String,
 }
 
-impl ToString for WalletExport {
+impl ToString for FullyNodedExport {
     fn to_string(&self) -> String {
         serde_json::to_string(self).unwrap()
     }
 }
 
-impl FromStr for WalletExport {
+impl FromStr for FullyNodedExport {
     type Err = serde_json::Error;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
@@ -99,7 +104,7 @@ fn remove_checksum(s: String) -> String {
     s.splitn(2, '#').next().map(String::from).unwrap()
 }
 
-impl WalletExport {
+impl FullyNodedExport {
     /// Export a wallet
     ///
     /// This function returns an error if it determines that the `wallet`'s descriptor(s) are not
@@ -117,8 +122,12 @@ impl WalletExport {
         include_blockheight: bool,
     ) -> Result<Self, &'static str> {
         let descriptor = wallet
-            .descriptor
+            .get_descriptor_for_keychain(KeychainKind::External)
-            .to_string_with_secret(&wallet.signers.as_key_map(wallet.secp_ctx()));
+            .to_string_with_secret(
+                &wallet
+                    .get_signers(KeychainKind::External)
+                    .as_key_map(wallet.secp_ctx()),
+            );
         let descriptor = remove_checksum(descriptor);
         Self::is_compatible_with_core(&descriptor)?;
 
@@ -136,18 +145,30 @@ impl WalletExport {
             }
         };
 
-        let export = WalletExport {
+        let export = FullyNodedExport {
             descriptor,
             label: label.into(),
             blockheight,
         };
 
-        let desc_to_string = |d: &Descriptor<DescriptorPublicKey>| {
+        let change_descriptor = match wallet
-            let descriptor =
+            .public_descriptor(KeychainKind::Internal)
-                d.to_string_with_secret(&wallet.change_signers.as_key_map(wallet.secp_ctx()));
+            .map_err(|_| "Invalid change descriptor")?
-            remove_checksum(descriptor)
+            .is_some()
+        {
+            false => None,
+            true => {
+                let descriptor = wallet
+                    .get_descriptor_for_keychain(KeychainKind::Internal)
+                    .to_string_with_secret(
+                        &wallet
+                            .get_signers(KeychainKind::Internal)
+                            .as_key_map(wallet.secp_ctx()),
+                    );
+                Some(remove_checksum(descriptor))
+            }
         };
-        if export.change_descriptor() != wallet.change_descriptor.as_ref().map(desc_to_string) {
+        if export.change_descriptor() != change_descriptor {
             return Err("Incompatible change descriptor");
         }
 
@@ -248,7 +269,7 @@ mod test {
             get_test_db(),
         )
         .unwrap();
-        let export = WalletExport::export_wallet(&wallet, "Test Label", true).unwrap();
+        let export = FullyNodedExport::export_wallet(&wallet, "Test Label", true).unwrap();
 
         assert_eq!(export.descriptor(), descriptor);
         assert_eq!(export.change_descriptor(), Some(change_descriptor.into()));
@@ -266,7 +287,7 @@ mod test {
         let descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/0/*)";
 
         let wallet = Wallet::new(descriptor, None, Network::Bitcoin, get_test_db()).unwrap();
-        WalletExport::export_wallet(&wallet, "Test Label", true).unwrap();
+        FullyNodedExport::export_wallet(&wallet, "Test Label", true).unwrap();
     }
 
     #[test]
@@ -285,7 +306,7 @@ mod test {
             get_test_db(),
         )
         .unwrap();
-        WalletExport::export_wallet(&wallet, "Test Label", true).unwrap();
+        FullyNodedExport::export_wallet(&wallet, "Test Label", true).unwrap();
     }
 
     #[test]
@@ -308,7 +329,7 @@ mod test {
             get_test_db(),
         )
         .unwrap();
-        let export = WalletExport::export_wallet(&wallet, "Test Label", true).unwrap();
+        let export = FullyNodedExport::export_wallet(&wallet, "Test Label", true).unwrap();
 
         assert_eq!(export.descriptor(), descriptor);
         assert_eq!(export.change_descriptor(), Some(change_descriptor.into()));
@@ -328,7 +349,7 @@ mod test {
             get_test_db(),
         )
         .unwrap();
-        let export = WalletExport::export_wallet(&wallet, "Test Label", true).unwrap();
+        let export = FullyNodedExport::export_wallet(&wallet, "Test Label", true).unwrap();
 
         assert_eq!(export.to_string(), "{\"descriptor\":\"wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44\'/0\'/0\'/0/*)\",\"blockheight\":5000,\"label\":\"Test Label\"}");
     }
@@ -339,7 +360,7 @@ mod test {
         let change_descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/1/*)";
 
         let import_str = "{\"descriptor\":\"wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44\'/0\'/0\'/0/*)\",\"blockheight\":5000,\"label\":\"Test Label\"}";
-        let export = WalletExport::from_str(import_str).unwrap();
+        let export = FullyNodedExport::from_str(import_str).unwrap();
 
         assert_eq!(export.descriptor(), descriptor);
         assert_eq!(export.change_descriptor(), Some(change_descriptor.into()));

src/wallet/mod.rs

@@ -140,6 +140,8 @@ pub struct AddressInfo {
     pub index: u32,
     /// Address
     pub address: Address,
+    /// Type of keychain
+    pub keychain: KeychainKind,
 }
 
 impl Deref for AddressInfo {
@@ -246,6 +248,7 @@ where
             .map(|address| AddressInfo {
                 address,
                 index: incremented_index,
+                keychain,
             })
             .map_err(|_| Error::ScriptDoesntHaveAddressForm)
     }
@@ -276,6 +279,7 @@ where
                 .map(|address| AddressInfo {
                     address,
                     index: current_index,
+                    keychain,
                 })
                 .map_err(|_| Error::ScriptDoesntHaveAddressForm)
         }
@@ -286,7 +290,11 @@ where
         self.get_descriptor_for_keychain(keychain)
             .as_derived(index, &self.secp)
             .address(self.network)
-            .map(|address| AddressInfo { index, address })
+            .map(|address| AddressInfo {
+                index,
+                address,
+                keychain,
+            })
             .map_err(|_| Error::ScriptDoesntHaveAddressForm)
     }
 
@@ -298,7 +306,11 @@ where
         self.get_descriptor_for_keychain(keychain)
             .as_derived(index, &self.secp)
             .address(self.network)
-            .map(|address| AddressInfo { index, address })
+            .map(|address| AddressInfo {
+                index,
+                address,
+                keychain,
+            })
             .map_err(|_| Error::ScriptDoesntHaveAddressForm)
     }
 
@@ -387,7 +399,13 @@ where
     /// Note that this method only operates on the internal database, which first needs to be
     /// [`Wallet::sync`] manually.
     pub fn list_unspent(&self) -> Result<Vec<LocalUtxo>, Error> {
-        self.database.borrow().iter_utxos()
+        Ok(self
+            .database
+            .borrow()
+            .iter_utxos()?
+            .into_iter()
+            .filter(|l| !l.is_spent)
+            .collect())
     }
 
     /// Returns the `UTXO` owned by this wallet corresponding to `outpoint` if it exists in the
@@ -450,6 +468,29 @@ where
         signers.add_external(signer.id(&self.secp), ordering, signer);
     }
 
+    /// Get the signers
+    ///
+    /// ## Example
+    ///
+    /// ```
+    /// # use bdk::{Wallet, KeychainKind};
+    /// # use bdk::bitcoin::Network;
+    /// # use bdk::database::MemoryDatabase;
+    /// let wallet = Wallet::new("wpkh(tprv8ZgxMBicQKsPe73PBRSmNbTfbcsZnwWhz5eVmhHpi31HW29Z7mc9B4cWGRQzopNUzZUT391DeDJxL2PefNunWyLgqCKRMDkU1s2s8bAfoSk/84'/0'/0'/0/*)", None, Network::Testnet, MemoryDatabase::new())?;
+    /// for secret_key in wallet.get_signers(KeychainKind::External).signers().iter().filter_map(|s| s.descriptor_secret_key()) {
+    ///     // secret_key: tprv8ZgxMBicQKsPe73PBRSmNbTfbcsZnwWhz5eVmhHpi31HW29Z7mc9B4cWGRQzopNUzZUT391DeDJxL2PefNunWyLgqCKRMDkU1s2s8bAfoSk/84'/0'/0'/0/*
+    ///     println!("secret_key: {}", secret_key);
+    /// }
+    ///
+    /// Ok::<(), Box<dyn std::error::Error>>(())
+    /// ```
+    pub fn get_signers(&self, keychain: KeychainKind) -> Arc<SignersContainer> {
+        match keychain {
+            KeychainKind::External => Arc::clone(&self.signers),
+            KeychainKind::Internal => Arc::clone(&self.change_signers),
+        }
+    }
+
     /// Add an address validator
     ///
     /// See [the `address_validator` module](address_validator) for an example.
@@ -457,6 +498,11 @@ where
         self.address_validators.push(validator);
     }
 
+    /// Get the address validators
+    pub fn get_address_validators(&self) -> &[Arc<dyn AddressValidator>] {
+        &self.address_validators
+    }
+
     /// Start building a transaction.
     ///
     /// This returns a blank [`TxBuilder`] from which you can specify the parameters for the transaction.
@@ -879,6 +925,7 @@ where
                     outpoint: txin.previous_output,
                     txout,
                     keychain,
+                    is_spent: true,
                 };
 
                 Ok(WeightedUtxo {
@@ -1549,6 +1596,18 @@ where
 
         Ok(())
     }
+
+    /// Return the checksum of the public descriptor associated to `keychain`
+    ///
+    /// Internally calls [`Self::get_descriptor_for_keychain`] to fetch the right descriptor
+    pub fn descriptor_checksum(&self, keychain: KeychainKind) -> String {
+        self.get_descriptor_for_keychain(keychain)
+            .to_string()
+            .splitn(2, '#')
+            .next()
+            .unwrap()
+            .to_string()
+    }
 }
 
 /// Return a fake wallet that appears to be funded for testing.
@@ -3917,6 +3976,7 @@ pub(crate) mod test {
             AddressInfo {
                 index: 0,
                 address: Address::from_str("tb1q6yn66vajcctph75pvylgkksgpp6nq04ppwct9a").unwrap(),
+                keychain: KeychainKind::External,
             }
         );
 
@@ -3925,7 +3985,8 @@ pub(crate) mod test {
             wallet.get_address(New).unwrap(),
             AddressInfo {
                 index: 1,
-                address: Address::from_str("tb1q4er7kxx6sssz3q7qp7zsqsdx4erceahhax77d7").unwrap()
+                address: Address::from_str("tb1q4er7kxx6sssz3q7qp7zsqsdx4erceahhax77d7").unwrap(),
+                keychain: KeychainKind::External,
             }
         );
 
@@ -3934,7 +3995,8 @@ pub(crate) mod test {
             wallet.get_address(Peek(25)).unwrap(),
             AddressInfo {
                 index: 25,
-                address: Address::from_str("tb1qsp7qu0knx3sl6536dzs0703u2w2ag6ppl9d0c2").unwrap()
+                address: Address::from_str("tb1qsp7qu0knx3sl6536dzs0703u2w2ag6ppl9d0c2").unwrap(),
+                keychain: KeychainKind::External,
             }
         );
 
@@ -3943,7 +4005,8 @@ pub(crate) mod test {
             wallet.get_address(New).unwrap(),
             AddressInfo {
                 index: 2,
-                address: Address::from_str("tb1qzntf2mqex4ehwkjlfdyy3ewdlk08qkvkvrz7x2").unwrap()
+                address: Address::from_str("tb1qzntf2mqex4ehwkjlfdyy3ewdlk08qkvkvrz7x2").unwrap(),
+                keychain: KeychainKind::External,
             }
         );
 
@@ -3952,7 +4015,8 @@ pub(crate) mod test {
             wallet.get_address(Reset(1)).unwrap(),
             AddressInfo {
                 index: 1,
-                address: Address::from_str("tb1q4er7kxx6sssz3q7qp7zsqsdx4erceahhax77d7").unwrap()
+                address: Address::from_str("tb1q4er7kxx6sssz3q7qp7zsqsdx4erceahhax77d7").unwrap(),
+                keychain: KeychainKind::External,
             }
         );
 
@@ -3961,7 +4025,8 @@ pub(crate) mod test {
             wallet.get_address(New).unwrap(),
             AddressInfo {
                 index: 2,
-                address: Address::from_str("tb1qzntf2mqex4ehwkjlfdyy3ewdlk08qkvkvrz7x2").unwrap()
+                address: Address::from_str("tb1qzntf2mqex4ehwkjlfdyy3ewdlk08qkvkvrz7x2").unwrap(),
+                keychain: KeychainKind::External,
             }
         );
     }
@@ -3990,15 +4055,21 @@ pub(crate) mod test {
         .unwrap();
 
         assert_eq!(
-            wallet.get_address(AddressIndex::New).unwrap().address,
+            wallet.get_address(AddressIndex::New).unwrap(),
-            Address::from_str("bcrt1qkmvk2nadgplmd57ztld8nf8v2yxkzmdvwtjf8s").unwrap()
+            AddressInfo {
+                index: 0,
+                address: Address::from_str("bcrt1qkmvk2nadgplmd57ztld8nf8v2yxkzmdvwtjf8s").unwrap(),
+                keychain: KeychainKind::External,
+            }
         );
+
         assert_eq!(
-            wallet
+            wallet.get_internal_address(AddressIndex::New).unwrap(),
-                .get_internal_address(AddressIndex::New)
+            AddressInfo {
-                .unwrap()
+                index: 0,
-                .address,
+                address: Address::from_str("bcrt1qtrwtz00wxl69e5xex7amy4xzlxkaefg3gfdkxa").unwrap(),
-            Address::from_str("bcrt1qtrwtz00wxl69e5xex7amy4xzlxkaefg3gfdkxa").unwrap()
+                keychain: KeychainKind::Internal,
+            }
         );
 
         let wallet = Wallet::new(
@@ -4010,11 +4081,12 @@ pub(crate) mod test {
         .unwrap();
 
         assert_eq!(
-            wallet
+            wallet.get_internal_address(AddressIndex::New).unwrap(),
-                .get_internal_address(AddressIndex::New)
+            AddressInfo {
-                .unwrap()
+                index: 0,
-                .address,
+                address: Address::from_str("bcrt1qkmvk2nadgplmd57ztld8nf8v2yxkzmdvwtjf8s").unwrap(),
-            Address::from_str("bcrt1qkmvk2nadgplmd57ztld8nf8v2yxkzmdvwtjf8s").unwrap(),
+                keychain: KeychainKind::Internal,
+            },
             "when there's no internal descriptor it should just use external"
         );
     }

src/wallet/tx_builder.rs

@@ -838,6 +838,7 @@ mod test {
                 },
                 txout: Default::default(),
                 keychain: KeychainKind::External,
+                is_spent: false,
             },
             LocalUtxo {
                 outpoint: OutPoint {
@@ -846,6 +847,7 @@ mod test {
                 },
                 txout: Default::default(),
                 keychain: KeychainKind::Internal,
+                is_spent: false,
             },
         ]
     }