Merge bitcoindevkit/bdk#1395: Remove rand dependency from bdk

4bddb0de6262fb4014d51baf8c9453eb45a3d0ef feat(wallet): add back TxBuilder finish() and sort_tx() with thread_rng() (Steve Myers)
45c0cae0a461232bf746375083e2005c5df5f913 fix(bdk): remove rand dependency (rustaceanrob)

Pull request description:

  ### Description

  WIP towards removing `rand` fixes #871

  The `rand` dependency was imported explicitly, but `rand` is also implicitly used through the `rand-std` feature flag on `bitcoin`.

  ### Notes to he reviewers

  **Updated:**

  `rand` was used primarily in two parts of `bdk`. Particularly in signing and in building a transaction.

  Signing:
  - Used implicitly in [`sign_schnorr`](https://docs.rs/bitcoin/latest/bitcoin/key/struct.Secp256k1.html#method.sign_schnorr), but nowhere else within `signer`.

  Transaction ordering:
  - Used to shuffle the inputs and outputs of a transaction, the default
  - Used in the single random draw __as a fallback__ to branch and bound during coin selection. Branch and bound is the default coin selection option.

  See conversation for proposed solutions.

  ### Changelog notice

  - Remove the `rand` dependency from `bdk`

  ### 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:

  * [x] I've added tests for the new feature
  * [x] I've added docs for the new feature

  #### Bugfixes:

  * [x] This pull request breaks the existing API
  * [x] I've added tests to reproduce the issue which are now passing
  * [x] I'm linking the issue being fixed by this PR

ACKs for top commit:
  ValuedMammal:
    ACK 4bddb0de6262fb4014d51baf8c9453eb45a3d0ef
  notmandatory:
    ACK 4bddb0de6262fb4014d51baf8c9453eb45a3d0ef

Tree-SHA512: 662d9bcb1e02f8195d73df16789b8c2aba8ccd7b37ba713ebb0bfd19c66163acbcb6f266b64f88347cbb1f96b88c8a150581012cbf818d1dc8b4437b3e53fc62

.github/workflows/cont_integration.yml

@@ -92,7 +92,7 @@ jobs:
         uses: Swatinem/rust-cache@v2.2.1
       - name: Check bdk wallet
         working-directory: ./crates/wallet
-        run: cargo check --target wasm32-unknown-unknown --no-default-features --features miniscript/no-std,bdk_chain/hashbrown,dev-getrandom-wasm
+        run: cargo check --target wasm32-unknown-unknown --no-default-features --features miniscript/no-std,bdk_chain/hashbrown
       - name: Check esplora
         working-directory: ./crates/esplora
         run: cargo check --target wasm32-unknown-unknown --no-default-features --features miniscript/no-std,bdk_chain/hashbrown,async

crates/esplora/src/blocking_ext.rs

@@ -1,6 +1,5 @@
 use std::collections::BTreeSet;
 use std::thread::JoinHandle;
-use std::usize;
 
 use bdk_chain::collections::BTreeMap;
 use bdk_chain::spk_client::{FullScanRequest, FullScanResult, SyncRequest, SyncResult};

crates/wallet/Cargo.toml

@@ -13,9 +13,9 @@ edition = "2021"
 rust-version = "1.63"
 
 [dependencies]
-rand = "^0.8"
+rand_core = { version = "0.6.0" }
 miniscript = { version = "12.0.0", features = ["serde"], default-features = false }
-bitcoin = { version = "0.32.0", features = ["serde", "base64", "rand-std"], default-features = false }
+bitcoin = { version = "0.32.0", features = ["serde", "base64"], default-features = false }
 serde = { version = "^1.0", features = ["derive"] }
 serde_json = { version = "^1.0" }
 bdk_chain = { path = "../chain", version = "0.16.0", features = ["miniscript", "serde"], default-features = false }
@@ -23,22 +23,13 @@ bdk_chain = { path = "../chain", version = "0.16.0", features = ["miniscript", "
 # Optional dependencies
 bip39 = { version = "2.0", optional = true }
 
-[target.'cfg(target_arch = "wasm32")'.dependencies]
-getrandom = "0.2"
-js-sys = "0.3"
-
 [features]
 default = ["std"]
-std = ["bitcoin/std", "miniscript/std", "bdk_chain/std"]
+std = ["bitcoin/std", "bitcoin/rand-std", "miniscript/std", "bdk_chain/std"]
 compiler = ["miniscript/compiler"]
 all-keys = ["keys-bip39"]
 keys-bip39 = ["bip39"]
 
-# This feature is used to run `cargo check` in our CI targeting wasm. It's not recommended
-# for libraries to explicitly include the "getrandom/js" feature, so we only do it when
-# necessary for running our CI. See: https://docs.rs/getrandom/0.2.8/getrandom/#webassembly-support
-dev-getrandom-wasm = ["getrandom/js"]
-
 [dev-dependencies]
 lazy_static = "1.4"
 assert_matches = "1.5.0"
@@ -46,6 +37,7 @@ tempfile = "3"
 bdk_sqlite = { path = "../sqlite" }
 bdk_file_store = { path = "../file_store" }
 anyhow = "1"
+rand = "^0.8"
 
 [package.metadata.docs.rs]
 all-features = true

crates/wallet/README.md

@@ -70,30 +70,28 @@ To persist `Wallet` state data use a data store crate that reads and writes [`bd
 ```rust,no_run
 use bdk_wallet::{bitcoin::Network, KeychainKind, wallet::{ChangeSet, Wallet}};
 
-fn main() {
+// Open or create a new file store for wallet data.
-    // Open or create a new file store for wallet data.
+let mut db =
-    let mut db =
+    bdk_file_store::Store::<ChangeSet>::open_or_create_new(b"magic_bytes", "/tmp/my_wallet.db")
-        bdk_file_store::Store::<ChangeSet>::open_or_create_new(b"magic_bytes", "/tmp/my_wallet.db")
+        .expect("create store");
-            .expect("create store");
 
-    // Create a wallet with initial wallet data read from the file store.
+// Create a wallet with initial wallet data read from the file store.
-    let descriptor = "wpkh(tprv8ZgxMBicQKsPdcAqYBpzAFwU5yxBUo88ggoBqu1qPcHUfSbKK1sKMLmC7EAk438btHQrSdu3jGGQa6PA71nvH5nkDexhLteJqkM4dQmWF9g/84'/1'/0'/0/*)";
+let descriptor = "wpkh(tprv8ZgxMBicQKsPdcAqYBpzAFwU5yxBUo88ggoBqu1qPcHUfSbKK1sKMLmC7EAk438btHQrSdu3jGGQa6PA71nvH5nkDexhLteJqkM4dQmWF9g/84'/1'/0'/0/*)";
-    let change_descriptor = "wpkh(tprv8ZgxMBicQKsPdcAqYBpzAFwU5yxBUo88ggoBqu1qPcHUfSbKK1sKMLmC7EAk438btHQrSdu3jGGQa6PA71nvH5nkDexhLteJqkM4dQmWF9g/84'/1'/0'/1/*)";
+let change_descriptor = "wpkh(tprv8ZgxMBicQKsPdcAqYBpzAFwU5yxBUo88ggoBqu1qPcHUfSbKK1sKMLmC7EAk438btHQrSdu3jGGQa6PA71nvH5nkDexhLteJqkM4dQmWF9g/84'/1'/0'/1/*)";
-    let changeset = db.aggregate_changesets().expect("changeset loaded");
+let changeset = db.aggregate_changesets().expect("changeset loaded");
-    let mut wallet =
+let mut wallet =
-        Wallet::new_or_load(descriptor, change_descriptor, changeset, Network::Testnet)
+    Wallet::new_or_load(descriptor, change_descriptor, changeset, Network::Testnet)
-            .expect("create or load wallet");
+        .expect("create or load wallet");
 
-    // Get a new address to receive bitcoin.
+// Get a new address to receive bitcoin.
-    let receive_address = wallet.reveal_next_address(KeychainKind::External);
+let receive_address = wallet.reveal_next_address(KeychainKind::External);
-    // Persist staged wallet data changes to the file store.
+// Persist staged wallet data changes to the file store.
-    let staged_changeset = wallet.take_staged();
+let staged_changeset = wallet.take_staged();
-    if let Some(changeset) = staged_changeset {
+if let Some(changeset) = staged_changeset {
-        db.append_changeset(&changeset)
+    db.append_changeset(&changeset)
-            .expect("must commit changes to database");
+        .expect("must commit changes to database");
-    }
-    println!("Your new receive address is: {}", receive_address.address);
 }
+println!("Your new receive address is: {}", receive_address.address);
 ```
 
 <!-- ### Sync the balance of a descriptor -->

crates/wallet/src/keys/mod.rs

@@ -20,6 +20,8 @@ use core::marker::PhantomData;
 use core::ops::Deref;
 use core::str::FromStr;
 
+use rand_core::{CryptoRng, RngCore};
+
 use bitcoin::secp256k1::{self, Secp256k1, Signing};
 
 use bitcoin::bip32;
@@ -631,12 +633,23 @@ pub trait GeneratableKey<Ctx: ScriptContext>: Sized {
         entropy: Self::Entropy,
     ) -> Result<GeneratedKey<Self, Ctx>, Self::Error>;
 
-    /// Generate a key given the options with a random entropy
+    /// Generate a key given the options with random entropy.
+    ///
+    /// Uses the thread-local random number generator.
+    #[cfg(feature = "std")]
     fn generate(options: Self::Options) -> Result<GeneratedKey<Self, Ctx>, Self::Error> {
-        use rand::{thread_rng, Rng};
+        Self::generate_with_aux_rand(options, &mut bitcoin::key::rand::thread_rng())
+    }
 
+    /// Generate a key given the options with random entropy.
+    ///
+    /// Uses a provided random number generator (rng).
+    fn generate_with_aux_rand(
+        options: Self::Options,
+        rng: &mut (impl CryptoRng + RngCore),
+    ) -> Result<GeneratedKey<Self, Ctx>, Self::Error> {
         let mut entropy = Self::Entropy::default();
-        thread_rng().fill(entropy.as_mut());
+        rng.fill_bytes(entropy.as_mut());
         Self::generate_with_entropy(options, entropy)
     }
 }
@@ -657,8 +670,20 @@ where
     }
 
     /// Generate a key with the default options and a random entropy
+    ///
+    /// Uses the thread-local random number generator.
+    #[cfg(feature = "std")]
     fn generate_default() -> Result<GeneratedKey<Self, Ctx>, Self::Error> {
-        Self::generate(Default::default())
+        Self::generate_with_aux_rand(Default::default(), &mut bitcoin::key::rand::thread_rng())
+    }
+
+    /// Generate a key with the default options and a random entropy
+    ///
+    /// Uses a provided random number generator (rng).
+    fn generate_default_with_aux_rand(
+        rng: &mut (impl CryptoRng + RngCore),
+    ) -> Result<GeneratedKey<Self, Ctx>, Self::Error> {
+        Self::generate_with_aux_rand(Default::default(), rng)
     }
 }
 

crates/wallet/src/wallet/coin_selection.rs

@@ -114,8 +114,9 @@ use bitcoin::{Script, Weight};
 
 use core::convert::TryInto;
 use core::fmt::{self, Formatter};
-use rand::seq::SliceRandom;
+use rand_core::RngCore;
 
+use super::utils::shuffle_slice;
 /// Default coin selection algorithm used by [`TxBuilder`](super::tx_builder::TxBuilder) if not
 /// overridden
 pub type DefaultCoinSelectionAlgorithm = BranchAndBoundCoinSelection;
@@ -516,27 +517,16 @@ impl CoinSelectionAlgorithm for BranchAndBoundCoinSelection {
             ));
         }
 
-        Ok(self
+        self.bnb(
-            .bnb(
+            required_utxos.clone(),
-                required_utxos.clone(),
+            optional_utxos.clone(),
-                optional_utxos.clone(),
+            curr_value,
-                curr_value,
+            curr_available_value,
-                curr_available_value,
+            target_amount,
-                target_amount,
+            cost_of_change,
-                cost_of_change,
+            drain_script,
-                drain_script,
+            fee_rate,
-                fee_rate,
+        )
-            )
-            .unwrap_or_else(|_| {
-                self.single_random_draw(
-                    required_utxos,
-                    optional_utxos,
-                    curr_value,
-                    target_amount,
-                    drain_script,
-                    fee_rate,
-                )
-            }))
     }
 }
 
@@ -663,40 +653,6 @@ impl BranchAndBoundCoinSelection {
         ))
     }
 
-    #[allow(clippy::too_many_arguments)]
-    fn single_random_draw(
-        &self,
-        required_utxos: Vec<OutputGroup>,
-        mut optional_utxos: Vec<OutputGroup>,
-        curr_value: i64,
-        target_amount: i64,
-        drain_script: &Script,
-        fee_rate: FeeRate,
-    ) -> CoinSelectionResult {
-        optional_utxos.shuffle(&mut rand::thread_rng());
-        let selected_utxos = optional_utxos.into_iter().fold(
-            (curr_value, vec![]),
-            |(mut amount, mut utxos), utxo| {
-                if amount >= target_amount {
-                    (amount, utxos)
-                } else {
-                    amount += utxo.effective_value;
-                    utxos.push(utxo);
-                    (amount, utxos)
-                }
-            },
-        );
-
-        // remaining_amount can't be negative as that would mean the
-        // selection wasn't successful
-        // target_amount = amount_needed + (fee_amount - vin_fees)
-        let remaining_amount = (selected_utxos.0 - target_amount) as u64;
-
-        let excess = decide_change(remaining_amount, fee_rate, drain_script);
-
-        BranchAndBoundCoinSelection::calculate_cs_result(selected_utxos.1, required_utxos, excess)
-    }
-
     fn calculate_cs_result(
         mut selected_utxos: Vec<OutputGroup>,
         mut required_utxos: Vec<OutputGroup>,
@@ -717,6 +673,58 @@ impl BranchAndBoundCoinSelection {
     }
 }
 
+// Pull UTXOs at random until we have enough to meet the target
+pub(crate) fn single_random_draw(
+    required_utxos: Vec<WeightedUtxo>,
+    optional_utxos: Vec<WeightedUtxo>,
+    target_amount: u64,
+    drain_script: &Script,
+    fee_rate: FeeRate,
+    rng: &mut impl RngCore,
+) -> CoinSelectionResult {
+    let target_amount = target_amount
+        .try_into()
+        .expect("Bitcoin amount to fit into i64");
+
+    let required_utxos: Vec<OutputGroup> = required_utxos
+        .into_iter()
+        .map(|u| OutputGroup::new(u, fee_rate))
+        .collect();
+
+    let mut optional_utxos: Vec<OutputGroup> = optional_utxos
+        .into_iter()
+        .map(|u| OutputGroup::new(u, fee_rate))
+        .collect();
+
+    let curr_value = required_utxos
+        .iter()
+        .fold(0, |acc, x| acc + x.effective_value);
+
+    shuffle_slice(&mut optional_utxos, rng);
+
+    let selected_utxos =
+        optional_utxos
+            .into_iter()
+            .fold((curr_value, vec![]), |(mut amount, mut utxos), utxo| {
+                if amount >= target_amount {
+                    (amount, utxos)
+                } else {
+                    amount += utxo.effective_value;
+                    utxos.push(utxo);
+                    (amount, utxos)
+                }
+            });
+
+    // remaining_amount can't be negative as that would mean the
+    // selection wasn't successful
+    // target_amount = amount_needed + (fee_amount - vin_fees)
+    let remaining_amount = (selected_utxos.0 - target_amount) as u64;
+
+    let excess = decide_change(remaining_amount, fee_rate, drain_script);
+
+    BranchAndBoundCoinSelection::calculate_cs_result(selected_utxos.1, required_utxos, excess)
+}
+
 /// Remove duplicate UTXOs.
 ///
 /// If a UTXO appears in both `required` and `optional`, the appearance in `required` is kept.
@@ -740,6 +748,7 @@ where
 mod test {
     use assert_matches::assert_matches;
     use core::str::FromStr;
+    use rand::rngs::StdRng;
 
     use bdk_chain::ConfirmationTime;
     use bitcoin::{Amount, ScriptBuf, TxIn, TxOut};
@@ -748,8 +757,7 @@ mod test {
     use crate::types::*;
     use crate::wallet::coin_selection::filter_duplicates;
 
-    use rand::rngs::StdRng;
+    use rand::prelude::SliceRandom;
-    use rand::seq::SliceRandom;
     use rand::{Rng, RngCore, SeedableRng};
 
     // signature len (1WU) + signature and sighash (72WU)
@@ -1090,13 +1098,12 @@ mod test {
     }
 
     #[test]
+    #[ignore = "SRD fn was moved out of BnB"]
     fn test_bnb_coin_selection_success() {
         // In this case bnb won't find a suitable match and single random draw will
         // select three outputs
         let utxos = generate_same_value_utxos(100_000, 20);
-
         let drain_script = ScriptBuf::default();
-
         let target_amount = 250_000 + FEE_AMOUNT;
 
         let result = BranchAndBoundCoinSelection::default()
@@ -1136,6 +1143,7 @@ mod test {
     }
 
     #[test]
+    #[ignore = "no exact match for bnb, previously fell back to SRD"]
     fn test_bnb_coin_selection_optional_are_enough() {
         let utxos = get_test_utxos();
         let drain_script = ScriptBuf::default();
@@ -1156,6 +1164,26 @@ mod test {
         assert_eq!(result.fee_amount, 136);
     }
 
+    #[test]
+    fn test_single_random_draw_function_success() {
+        let seed = [0; 32];
+        let mut rng: StdRng = SeedableRng::from_seed(seed);
+        let mut utxos = generate_random_utxos(&mut rng, 300);
+        let target_amount = sum_random_utxos(&mut rng, &mut utxos) + FEE_AMOUNT;
+        let fee_rate = FeeRate::from_sat_per_vb_unchecked(1);
+        let drain_script = ScriptBuf::default();
+        let result = single_random_draw(
+            vec![],
+            utxos,
+            target_amount,
+            &drain_script,
+            fee_rate,
+            &mut rng,
+        );
+        assert!(result.selected_amount() > target_amount);
+        assert_eq!(result.fee_amount, (result.selected.len() * 68) as u64);
+    }
+
     #[test]
     #[ignore]
     fn test_bnb_coin_selection_required_not_enough() {
@@ -1410,34 +1438,6 @@ mod test {
         }
     }
 
-    #[test]
-    fn test_single_random_draw_function_success() {
-        let seed = [0; 32];
-        let mut rng: StdRng = SeedableRng::from_seed(seed);
-        let mut utxos = generate_random_utxos(&mut rng, 300);
-        let target_amount = sum_random_utxos(&mut rng, &mut utxos) + FEE_AMOUNT;
-
-        let fee_rate = FeeRate::from_sat_per_vb_unchecked(1);
-        let utxos: Vec<OutputGroup> = utxos
-            .into_iter()
-            .map(|u| OutputGroup::new(u, fee_rate))
-            .collect();
-
-        let drain_script = ScriptBuf::default();
-
-        let result = BranchAndBoundCoinSelection::default().single_random_draw(
-            vec![],
-            utxos,
-            0,
-            target_amount as i64,
-            &drain_script,
-            fee_rate,
-        );
-
-        assert!(result.selected_amount() > target_amount);
-        assert_eq!(result.fee_amount, (result.selected.len() * 68) as u64);
-    }
-
     #[test]
     fn test_bnb_exclude_negative_effective_value() {
         let utxos = get_test_utxos();

crates/wallet/src/wallet/mod.rs

@@ -42,6 +42,8 @@ use bitcoin::{constants::genesis_block, Amount};
 use core::fmt;
 use core::mem;
 use core::ops::Deref;
+use rand_core::RngCore;
+
 use descriptor::error::Error as DescriptorError;
 use miniscript::psbt::{PsbtExt, PsbtInputExt, PsbtInputSatisfier};
 
@@ -1238,6 +1240,7 @@ impl Wallet {
         &mut self,
         coin_selection: Cs,
         params: TxParams,
+        rng: &mut impl RngCore,
     ) -> Result<Psbt, CreateTxError> {
         let keychains: BTreeMap<_, _> = self.indexed_graph.index.keychains().collect();
         let external_descriptor = keychains.get(&KeychainKind::External).expect("must exist");
@@ -1464,13 +1467,31 @@ impl Wallet {
         let (required_utxos, optional_utxos) =
             coin_selection::filter_duplicates(required_utxos, optional_utxos);
 
-        let coin_selection = coin_selection.coin_select(
+        let coin_selection = match coin_selection.coin_select(
-            required_utxos,
+            required_utxos.clone(),
-            optional_utxos,
+            optional_utxos.clone(),
             fee_rate,
             outgoing.to_sat() + fee_amount,
             &drain_script,
-        )?;
+        ) {
+            Ok(res) => res,
+            Err(e) => match e {
+                coin_selection::Error::InsufficientFunds { .. } => {
+                    return Err(CreateTxError::CoinSelection(e));
+                }
+                coin_selection::Error::BnBNoExactMatch
+                | coin_selection::Error::BnBTotalTriesExceeded => {
+                    coin_selection::single_random_draw(
+                        required_utxos,
+                        optional_utxos,
+                        outgoing.to_sat() + fee_amount,
+                        &drain_script,
+                        fee_rate,
+                        rng,
+                    )
+                }
+            },
+        };
         fee_amount += coin_selection.fee_amount;
         let excess = &coin_selection.excess;
 
@@ -1534,7 +1555,7 @@ impl Wallet {
         };
 
         // sort input/outputs according to the chosen algorithm
-        params.ordering.sort_tx(&mut tx);
+        params.ordering.sort_tx_with_aux_rand(&mut tx, rng);
 
         let psbt = self.complete_transaction(tx, coin_selection.selected, params)?;
         Ok(psbt)

crates/wallet/src/wallet/signer.rs

@@ -607,7 +607,7 @@ fn sign_psbt_schnorr(
     };
 
     let msg = &Message::from(hash);
-    let signature = secp.sign_schnorr(msg, &keypair);
+    let signature = secp.sign_schnorr_no_aux_rand(msg, &keypair);
     secp.verify_schnorr(&signature, msg, &XOnlyPublicKey::from_keypair(&keypair).0)
         .expect("invalid or corrupted schnorr signature");
 

crates/wallet/src/wallet/tx_builder.rs

@@ -45,8 +45,10 @@ use core::fmt;
 use bitcoin::psbt::{self, Psbt};
 use bitcoin::script::PushBytes;
 use bitcoin::{absolute, Amount, FeeRate, OutPoint, ScriptBuf, Sequence, Transaction, Txid};
+use rand_core::RngCore;
 
 use super::coin_selection::CoinSelectionAlgorithm;
+use super::utils::shuffle_slice;
 use super::{CreateTxError, Wallet};
 use crate::collections::{BTreeMap, HashSet};
 use crate::{KeychainKind, LocalOutput, Utxo, WeightedUtxo};
@@ -669,16 +671,33 @@ impl<'a, Cs> TxBuilder<'a, Cs> {
 impl<'a, Cs: CoinSelectionAlgorithm> TxBuilder<'a, Cs> {
     /// Finish building the transaction.
     ///
+    /// Uses the thread-local random number generator (rng).
+    ///
     /// Returns a new [`Psbt`] per [`BIP174`].
     ///
     /// [`BIP174`]: https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki
     ///
     /// **WARNING**: To avoid change address reuse you must persist the changes resulting from one
     /// or more calls to this method before closing the wallet. See [`Wallet::reveal_next_address`].
+    #[cfg(feature = "std")]
     pub fn finish(self) -> Result<Psbt, CreateTxError> {
+        self.finish_with_aux_rand(&mut bitcoin::key::rand::thread_rng())
+    }
+
+    /// Finish building the transaction.
+    ///
+    /// Uses a provided random number generator (rng).
+    ///
+    /// Returns a new [`Psbt`] per [`BIP174`].
+    ///
+    /// [`BIP174`]: https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki
+    ///
+    /// **WARNING**: To avoid change address reuse you must persist the changes resulting from one
+    /// or more calls to this method before closing the wallet. See [`Wallet::reveal_next_address`].
+    pub fn finish_with_aux_rand(self, rng: &mut impl RngCore) -> Result<Psbt, CreateTxError> {
         self.wallet
             .borrow_mut()
-            .create_tx(self.coin_selection, self.params)
+            .create_tx(self.coin_selection, self.params, rng)
     }
 }
 
@@ -757,15 +776,23 @@ pub enum TxOrdering {
 }
 
 impl TxOrdering {
-    /// Sort transaction inputs and outputs by [`TxOrdering`] variant
+    /// Sort transaction inputs and outputs by [`TxOrdering`] variant.
-    pub fn sort_tx(&self, tx: &mut Transaction) {
+    ///
+    /// Uses the thread-local random number generator (rng).
+    #[cfg(feature = "std")]
+    pub fn sort_tx(self, tx: &mut Transaction) {
+        self.sort_tx_with_aux_rand(tx, &mut bitcoin::key::rand::thread_rng())
+    }
+
+    /// Sort transaction inputs and outputs by [`TxOrdering`] variant.
+    ///
+    /// Uses a provided random number generator (rng).
+    pub fn sort_tx_with_aux_rand(self, tx: &mut Transaction, rng: &mut impl RngCore) {
         match self {
             TxOrdering::Untouched => {}
             TxOrdering::Shuffle => {
-                use rand::seq::SliceRandom;
+                shuffle_slice(&mut tx.input, rng);
-                let mut rng = rand::thread_rng();
+                shuffle_slice(&mut tx.output, rng);
-                tx.input.shuffle(&mut rng);
-                tx.output.shuffle(&mut rng);
             }
             TxOrdering::Bip69Lexicographic => {
                 tx.input.sort_unstable_by_key(|txin| {
@@ -851,12 +878,6 @@ mod test {
     use bitcoin::TxOut;
 
     use super::*;
-
-    #[test]
-    fn test_output_ordering_default_shuffle() {
-        assert_eq!(TxOrdering::default(), TxOrdering::Shuffle);
-    }
-
     #[test]
     fn test_output_ordering_untouched() {
         let original_tx = ordering_test_tx!();

crates/wallet/src/wallet/utils.rs

@@ -14,6 +14,8 @@ use bitcoin::{absolute, relative, Script, Sequence};
 
 use miniscript::{MiniscriptKey, Satisfier, ToPublicKey};
 
+use rand_core::RngCore;
+
 /// Trait to check if a value is below the dust limit.
 /// We are performing dust value calculation for a given script public key using rust-bitcoin to
 /// keep it compatible with network dust rate
@@ -110,6 +112,19 @@ impl<Pk: MiniscriptKey + ToPublicKey> Satisfier<Pk> for Older {
     }
 }
 
+// The Knuth shuffling algorithm based on the original [Fisher-Yates method](https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle)
+pub(crate) fn shuffle_slice<T>(list: &mut [T], rng: &mut impl RngCore) {
+    if list.is_empty() {
+        return;
+    }
+    let mut current_index = list.len() - 1;
+    while current_index > 0 {
+        let random_index = rng.next_u32() as usize % (current_index + 1);
+        list.swap(current_index, random_index);
+        current_index -= 1;
+    }
+}
+
 pub(crate) type SecpCtx = Secp256k1<All>;
 
 #[cfg(test)]
@@ -118,9 +133,11 @@ mod test {
     // otherwise it's time-based
     pub(crate) const SEQUENCE_LOCKTIME_TYPE_FLAG: u32 = 1 << 22;
 
-    use super::{check_nsequence_rbf, IsDust};
+    use super::{check_nsequence_rbf, shuffle_slice, IsDust};
     use crate::bitcoin::{Address, Network, Sequence};
+    use alloc::vec::Vec;
     use core::str::FromStr;
+    use rand::{rngs::StdRng, thread_rng, SeedableRng};
 
     #[test]
     fn test_is_dust() {
@@ -182,4 +199,46 @@ mod test {
         );
         assert!(result);
     }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn test_shuffle_slice_empty_vec() {
+        let mut test: Vec<u8> = vec![];
+        shuffle_slice(&mut test, &mut thread_rng());
+    }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn test_shuffle_slice_single_vec() {
+        let mut test: Vec<u8> = vec![0];
+        shuffle_slice(&mut test, &mut thread_rng());
+    }
+
+    #[test]
+    fn test_shuffle_slice_duple_vec() {
+        let seed = [0; 32];
+        let mut rng: StdRng = SeedableRng::from_seed(seed);
+        let mut test: Vec<u8> = vec![0, 1];
+        shuffle_slice(&mut test, &mut rng);
+        assert_eq!(test, &[0, 1]);
+        let seed = [6; 32];
+        let mut rng: StdRng = SeedableRng::from_seed(seed);
+        let mut test: Vec<u8> = vec![0, 1];
+        shuffle_slice(&mut test, &mut rng);
+        assert_eq!(test, &[1, 0]);
+    }
+
+    #[test]
+    fn test_shuffle_slice_multi_vec() {
+        let seed = [0; 32];
+        let mut rng: StdRng = SeedableRng::from_seed(seed);
+        let mut test: Vec<u8> = vec![0, 1, 2, 4, 5];
+        shuffle_slice(&mut test, &mut rng);
+        assert_eq!(test, &[2, 1, 0, 4, 5]);
+        let seed = [25; 32];
+        let mut rng: StdRng = SeedableRng::from_seed(seed);
+        let mut test: Vec<u8> = vec![0, 1, 2, 4, 5];
+        shuffle_slice(&mut test, &mut rng);
+        assert_eq!(test, &[0, 4, 1, 2, 5]);
+    }
 }

crates/wallet/tests/wallet.rs

@@ -24,6 +24,8 @@ use bitcoin::{
     absolute, transaction, Address, Amount, BlockHash, FeeRate, Network, OutPoint, ScriptBuf,
     Sequence, Transaction, TxIn, TxOut, Txid, Weight,
 };
+use rand::rngs::StdRng;
+use rand::SeedableRng;
 
 mod common;
 use common::*;
@@ -907,14 +909,15 @@ fn test_create_tx_absolute_high_fee() {
 #[test]
 fn test_create_tx_add_change() {
     use bdk_wallet::wallet::tx_builder::TxOrdering;
-
+    let seed = [0; 32];
+    let mut rng: StdRng = SeedableRng::from_seed(seed);
     let (mut wallet, _) = get_funded_wallet_wpkh();
     let addr = wallet.next_unused_address(KeychainKind::External);
     let mut builder = wallet.build_tx();
     builder
         .add_recipient(addr.script_pubkey(), Amount::from_sat(25_000))
-        .ordering(TxOrdering::Untouched);
+        .ordering(TxOrdering::Shuffle);
-    let psbt = builder.finish().unwrap();
+    let psbt = builder.finish_with_aux_rand(&mut rng).unwrap();
     let fee = check_fee!(wallet, psbt);
 
     assert_eq!(psbt.unsigned_tx.output.len(), 2);