mirror of https://github.com/zcash/orchard.git
tree::testing: Fix and test arb_tree().
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2d0afe9357
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b3daeb0861
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@ -522,7 +522,7 @@ pub mod testing {
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/// Produce a random valid Orchard bundle.
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fn arb_bundle_inputs(sk: SpendingKey)
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(
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n_notes in 1..30,
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n_notes in 1usize..30,
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n_recipients in 1..30,
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)
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(
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@ -47,11 +47,6 @@ impl NoteCommitment {
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pub struct ExtractedNoteCommitment(pub(super) pallas::Base);
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impl ExtractedNoteCommitment {
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/// ExtractedNoteCommitment for an uncommitted note.
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pub fn uncommitted() -> Self {
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Self(pallas::Base::zero())
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}
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/// Deserialize the extracted note commitment from a byte array.
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pub fn from_bytes(bytes: &[u8; 32]) -> CtOption<Self> {
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pallas::Base::from_bytes(bytes).map(ExtractedNoteCommitment)
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147
src/tree.rs
147
src/tree.rs
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@ -40,6 +40,14 @@ impl MerklePath {
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}
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}
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/// <https://zips.z.cash/protocol/protocol.pdf#orchardmerklecrh>
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/// The layer with 2^n nodes is called "layer n":
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/// - leaves are at layer MERKLE_DEPTH_ORCHARD = 32;
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/// - the root is at layer 0.
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/// `l_star` is MERKLE_DEPTH_ORCHARD - layer - 1.
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/// - when hashing two leaves, we produce a node on the layer above the leaves, i.e.
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/// layer = 31, l_star = 0
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/// - when hashing to the final root, we produce the anchor with layer = 0, l_star = 31.
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pub fn root(&self, cmx: ExtractedNoteCommitment) -> Anchor {
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let node = self
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.auth_path
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@ -73,6 +81,13 @@ fn cond_swap(swap: bool, node: pallas::Base, sibling: pallas::Base) -> Pair {
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}
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// <https://zips.z.cash/protocol/protocol.pdf#orchardmerklecrh>
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// The layer with 2^n nodes is called "layer n":
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// - leaves are at layer MERKLE_DEPTH_ORCHARD = 32;
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// - the root is at layer 0.
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// `l_star` is MERKLE_DEPTH_ORCHARD - layer - 1.
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// - when hashing two leaves, we produce a node on the layer above the leaves, i.e.
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// layer = 31, l_star = 0
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// - when hashing to the final root, we produce the anchor with layer = 0, l_star = 31.
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fn hash_layer(l_star: usize, pair: Pair) -> pallas::Base {
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// MerkleCRH Sinsemilla hash domain.
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let domain = HashDomain::new(MERKLE_CRH_PERSONALIZATION);
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@ -104,14 +119,13 @@ fn hash_layer(l_star: usize, pair: Pair) -> pallas::Base {
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pub mod testing {
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use lazy_static::lazy_static;
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use std::convert::TryInto;
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use std::iter;
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use crate::{
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constants::{MERKLE_CRH_PERSONALIZATION, MERKLE_DEPTH_ORCHARD},
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constants::MERKLE_DEPTH_ORCHARD,
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note::{commitment::ExtractedNoteCommitment, testing::arb_note, Note},
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primitives::sinsemilla::{i2lebsp_k, HashDomain, K},
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value::{testing::arb_positive_note_value, MAX_NOTE_VALUE},
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};
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use ff::{PrimeField, PrimeFieldBits};
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use pasta_curves::pallas;
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use proptest::collection::vec;
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@ -121,95 +135,113 @@ pub mod testing {
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lazy_static! {
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static ref EMPTY_ROOTS: Vec<pallas::Base> = {
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// MerkleCRH Sinsemilla hash domain.
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let domain = HashDomain::new(MERKLE_CRH_PERSONALIZATION);
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let mut v = vec![pallas::Base::zero()];
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for l_star in 0..MERKLE_DEPTH_ORCHARD {
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let next = domain
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.hash(
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std::iter::empty()
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.chain(i2lebsp_k(l_star).iter().copied().take(K))
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.chain(
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v[l_star]
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.to_le_bits()
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.iter()
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.by_val()
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.take(pallas::Base::NUM_BITS as usize)
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)
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.chain(
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v[l_star]
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.to_le_bits()
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.iter()
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.by_val()
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.take(pallas::Base::NUM_BITS as usize)
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),
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iter::empty()
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.chain(Some(pallas::Base::zero()))
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.chain(
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(0..MERKLE_DEPTH_ORCHARD).scan(pallas::Base::zero(), |state, l_star| {
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*state = hash_layer(
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l_star,
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Pair {
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left: *state,
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right: *state,
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},
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);
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Some(*state)
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}),
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)
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.unwrap();
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v.push(next);
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}
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v
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.collect()
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};
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}
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prop_compose! {
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/// Generates an arbitrary Merkle tree of with `n_notes` nonempty leaves.
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pub fn arb_tree(n_notes: i32)
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pub fn arb_tree(n_notes: usize)
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(
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// generate note values that we're certain won't exceed MAX_NOTE_VALUE in total
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notes in vec(
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arb_positive_note_value(MAX_NOTE_VALUE / n_notes as u64).prop_flat_map(arb_note),
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n_notes as usize
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n_notes
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),
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)
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-> (Vec<(Note, MerklePath)>, Anchor) {
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// Inefficient algorithm to build a perfect subtree containing all notes.
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let perfect_subtree_depth = (n_notes as f64).log2().ceil() as usize;
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let commitments: Vec<ExtractedNoteCommitment> = notes.iter().map(|note| {
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let n_leaves = 1 << perfect_subtree_depth;
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let commitments: Vec<Option<ExtractedNoteCommitment>> = notes.iter().map(|note| {
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let cmx: ExtractedNoteCommitment = note.commitment().into();
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cmx
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Some(cmx)
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}).collect();
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let padded_leaves = {
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let mut padded_leaves = commitments.clone();
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let pad = (0..((1 << perfect_subtree_depth) - n_notes as usize)).map(
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|_| ExtractedNoteCommitment::uncommitted()
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let pad = (0..(n_leaves - n_notes)).map(
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|_| None
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).collect::<Vec<_>>();
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padded_leaves.extend_from_slice(&pad);
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padded_leaves
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};
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let tree = {
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let mut tree: Vec<Vec<pallas::Base>> = vec![padded_leaves.into_iter().map(|leaf| *leaf).collect()];
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let perfect_subtree = {
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let mut perfect_subtree: Vec<Vec<Option<pallas::Base>>> = vec![
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padded_leaves.iter().map(|cmx| cmx.map(|cmx| *cmx)).collect()
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];
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// <https://zips.z.cash/protocol/protocol.pdf#orchardmerklecrh>
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// The layer with 2^n nodes is called "layer n":
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// - leaves are at layer MERKLE_DEPTH_ORCHARD = 32;
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// - the root is at layer 0.
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// `l_star` is MERKLE_DEPTH_ORCHARD - layer - 1.
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// - when hashing two leaves, we produce a node on the layer above the leaves, i.e.
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// layer = 31, l_star = 0
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// - when hashing to the final root, we produce the anchor with layer = 0, l_star = 31.
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for height in 1..perfect_subtree_depth {
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let inner_nodes = (0..(perfect_subtree_depth >> height)).map(|pos| {
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hash_layer(height, Pair {
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left: tree[height - 1][pos * 2],
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right: tree[height - 1][pos * 2 + 1],
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})
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let l_star = height - 1;
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let inner_nodes = (0..(n_leaves >> height)).map(|pos| {
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let left = perfect_subtree[height - 1][pos * 2];
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let right = perfect_subtree[height - 1][pos * 2 + 1];
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match (left, right) {
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(None, None) => None,
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(Some(left), None) => {
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let right = EMPTY_ROOTS[height - 1];
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Some(hash_layer(l_star, Pair {left, right}))
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},
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(Some(left), Some(right)) => {
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Some(hash_layer(l_star, Pair {left, right}))
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},
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(None, Some(_)) => {
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unreachable!("The perfect subtree is left-packed.")
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}
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}
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}).collect();
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tree.push(inner_nodes);
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perfect_subtree.push(inner_nodes);
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};
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tree
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perfect_subtree
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};
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// Get Merkle path for each note commitment
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let auth_paths = {
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let mut auth_paths: Vec<MerklePath> = Vec::new();
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for (pos, _) in commitments.iter().enumerate() {
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// Initialize the authentication path to the path for an empty tree.
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let mut auth_path: [pallas::Base; MERKLE_DEPTH_ORCHARD] = (0..MERKLE_DEPTH_ORCHARD).map(|idx| EMPTY_ROOTS[idx]).collect::<Vec<_>>().try_into().unwrap();
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let mut layer_pos = pos;
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for height in 0..perfect_subtree_depth {
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let is_right_sibling = layer_pos & 1 == 1;
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let sibling = if is_right_sibling {
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tree[height][layer_pos - 1]
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// This node is the right sibling, so we need its left sibling at the current height.
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perfect_subtree[height][layer_pos - 1]
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} else {
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tree[height][layer_pos + 1]
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// This node is the left sibling, so we need its right sibling at the current height.
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perfect_subtree[height][layer_pos + 1]
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};
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auth_path[height] = sibling;
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if let Some(sibling) = sibling {
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auth_path[height] = sibling;
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}
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layer_pos = (layer_pos - is_right_sibling as usize) / 2;
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};
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@ -220,11 +252,7 @@ pub mod testing {
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};
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// Compute anchor for this tree
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let anchor = auth_paths[0].root(commitments[0]);
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for (cmx, auth_path) in commitments.iter().zip(auth_paths.iter()) {
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let computed_anchor = auth_path.root(*cmx);
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assert_eq!(anchor, computed_anchor);
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}
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let anchor = auth_paths[0].root(notes[0].commitment().into());
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(
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notes.into_iter().zip(auth_paths.into_iter()).map(|(note, auth_path)| (note, auth_path)).collect(),
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@ -232,4 +260,17 @@ pub mod testing {
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)
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}
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}
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proptest! {
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#[allow(clippy::redundant_closure)]
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#[test]
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fn tree(
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(notes_and_auth_paths, anchor) in (1usize..4).prop_flat_map(|n_notes| arb_tree(n_notes))
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) {
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for (note, auth_path) in notes_and_auth_paths.iter() {
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let computed_anchor = auth_path.root(note.commitment().into());
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assert_eq!(anchor, computed_anchor);
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}
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}
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}
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}
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