1355 lines
42 KiB
Rust
1355 lines
42 KiB
Rust
//! # `incrementalmerkletree`
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//!
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//! Incremental Merkle Trees are fixed-depth Merkle trees with two primary
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//! capabilities: appending (assigning a value to the next unused leaf and
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//! advancing the tree) and obtaining the root of the tree. Importantly the tree
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//! structure attempts to store the least amount of information necessary to
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//! continue to function; other information should be pruned eagerly to avoid
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//! waste when the tree state is encoded.
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//!
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//! ## Witnessing
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//!
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//! Merkle trees are typically used to show that a value exists in the tree via
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//! an authentication path. We need an API that allows us to identify the
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//! current leaf as a value we wish to compute authentication paths for even as
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//! the tree continues to be appended to in the future; this is called
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//! maintaining a witness. When we're later uninterested in such a leaf, we can
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//! prune a witness and remove all unnecessary information from the structure as
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//! a consequence.
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//!
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//! ## Checkpoints and Rollbacks
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//!
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//! The structure is not append-only in the strict sense. It is possible to
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//! identify the current state of the tree as a "checkpoint" and to remove older
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//! checkpoints that we're no longer interested in. It should be possible to
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//! roll back to any previous checkpoint.
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pub mod bridgetree;
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mod sample;
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use serde::{Deserialize, Serialize};
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use std::collections::BTreeSet;
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use std::convert::TryFrom;
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use std::num::TryFromIntError;
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use std::ops::{Add, AddAssign, Sub};
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/// A type-safe wrapper for indexing into "levels" of a binary tree, such that
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/// nodes at altitude `0` are leaves, nodes at altitude `1` are parents
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/// of nodes at altitude `0`, and so forth. This type is capable of
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/// representing altitudes in trees containing up to 2^255 leaves.
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#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
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#[repr(transparent)]
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pub struct Altitude(u8);
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impl Altitude {
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/// Convenience method for returning the zero altitude.
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pub fn zero() -> Self {
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Self(0)
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}
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pub fn one() -> Self {
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Self(1)
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}
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pub fn iter_to(self, other: Altitude) -> impl Iterator<Item = Self> {
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(self.0..other.0).into_iter().map(Altitude)
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}
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}
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impl Add<u8> for Altitude {
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type Output = Self;
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fn add(self, value: u8) -> Self {
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Self(self.0 + value)
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}
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}
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impl Sub<u8> for Altitude {
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type Output = Self;
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fn sub(self, value: u8) -> Self {
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Self(self.0 - value)
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}
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}
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impl From<u8> for Altitude {
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fn from(value: u8) -> Self {
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Self(value)
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}
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}
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impl From<Altitude> for u8 {
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fn from(level: Altitude) -> u8 {
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level.0
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}
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}
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impl From<Altitude> for usize {
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fn from(level: Altitude) -> usize {
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level.0 as usize
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}
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}
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/// A type representing the position of a leaf in a Merkle tree.
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#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
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#[repr(transparent)]
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pub struct Position(usize);
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impl Position {
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/// Returns the position of the first leaf in the tree.
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pub fn zero() -> Self {
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Self(0)
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}
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/// Returns the altitude of the top of a binary tree containing
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/// a number of nodes equal to the next power of two greater than
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/// or equal to `self + 1`.
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fn max_altitude(&self) -> Altitude {
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Altitude(if self.0 == 0 {
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0
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} else {
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63 - self.0.leading_zeros() as u8
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})
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}
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/// Returns the altitude of each populated ommer.
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pub fn ommer_altitudes(&self) -> impl Iterator<Item = Altitude> + '_ {
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(0..=self.max_altitude().0)
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.into_iter()
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.filter_map(move |i| {
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if i != 0 && self.0 & (1 << i) != 0 {
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Some(Altitude(i))
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} else {
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None
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}
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})
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}
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/// Returns the altitude of each cousin and/or ommer required to construct
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/// an authentication path to the root of a merkle tree that has `self + 1`
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/// nodes.
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pub fn altitudes_required(&self) -> impl Iterator<Item = Altitude> + '_ {
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(0..=self.max_altitude().0)
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.into_iter()
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.filter_map(move |i| {
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if self.0 == 0 || self.0 & (1 << i) == 0 {
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Some(Altitude(i))
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} else {
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None
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}
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})
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}
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/// Returns the altitude of each cousin and/or ommer required to construct
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/// an authentication path to the root of a merkle tree containing 2^64
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/// nodes.
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pub fn all_altitudes_required(&self) -> impl Iterator<Item = Altitude> + '_ {
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(0..64).into_iter().filter_map(move |i| {
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if self.0 == 0 || self.0 & (1 << i) == 0 {
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Some(Altitude(i))
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} else {
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None
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}
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})
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}
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/// Returns whether the binary tree having `self` as the position of the
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/// rightmost leaf contains a perfect balanced tree of height
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/// `to_altitude + 1` that contains the aforesaid leaf, without requiring
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/// any empty leaves or internal nodes.
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pub fn is_complete(&self, to_altitude: Altitude) -> bool {
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for i in 0..(to_altitude.0) {
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if self.0 & (1 << i) == 0 {
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return false;
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}
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}
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true
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}
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}
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impl From<Position> for usize {
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fn from(p: Position) -> usize {
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p.0
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}
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}
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impl From<Position> for u64 {
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fn from(p: Position) -> Self {
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p.0 as u64
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}
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}
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impl Add<usize> for Position {
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type Output = Position;
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fn add(self, other: usize) -> Self {
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Position(self.0 + other)
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}
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}
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impl AddAssign<usize> for Position {
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fn add_assign(&mut self, other: usize) {
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self.0 += other
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}
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}
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impl From<usize> for Position {
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fn from(sz: usize) -> Self {
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Self(sz)
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}
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}
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impl TryFrom<u64> for Position {
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type Error = TryFromIntError;
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fn try_from(sz: u64) -> Result<Self, Self::Error> {
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<usize>::try_from(sz).map(Self)
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}
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}
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/// A trait describing the operations that make a value suitable for inclusion in
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/// an incremental merkle tree.
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pub trait Hashable: Sized {
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fn empty_leaf() -> Self;
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fn combine(level: Altitude, a: &Self, b: &Self) -> Self;
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fn empty_root(level: Altitude) -> Self {
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Altitude::zero()
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.iter_to(level)
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.fold(Self::empty_leaf(), |v, lvl| Self::combine(lvl, &v, &v))
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}
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}
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/// A possibly-empty incremental Merkle frontier.
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pub trait Frontier<H> {
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/// Appends a new value to the frontier at the next available slot.
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/// Returns true if successful and false if the frontier would exceed
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/// the maximum allowed depth.
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fn append(&mut self, value: &H) -> bool;
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/// Obtains the current root of this Merkle frontier by hashing
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/// against empty nodes up to the maximum height of the pruned
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/// tree that the frontier represents.
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fn root(&self) -> H;
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}
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/// A Merkle tree that supports incremental appends, witnessing of
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/// leaf nodes, checkpoints and rollbacks.
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pub trait Tree<H> {
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/// Appends a new value to the tree at the next available slot.
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/// Returns true if successful and false if the tree would exceed
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/// the maximum allowed depth.
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fn append(&mut self, value: &H) -> bool;
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/// Returns the most recently appended leaf value.
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fn current_position(&self) -> Option<Position>;
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/// Returns the most recently appended leaf value.
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fn current_leaf(&self) -> Option<&H>;
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/// Returns the leaf at the specified position if the tree can produce
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/// an authentication path for it.
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fn get_witnessed_leaf(&self, position: Position) -> Option<&H>;
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/// Marks the current leaf as one for which we're interested in producing
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/// an authentication path. Returns an optional value containing the
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/// current position if successful or if the current value was already
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/// marked, or None if the tree is empty.
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fn witness(&mut self) -> Option<Position>;
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/// Return a set of all the positions for which we have witnessed.
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fn witnessed_positions(&self) -> BTreeSet<Position>;
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/// Obtains the root of the Merkle tree at the specified checkpoint depth
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/// by hashing against empty nodes up to the maximum height of the tree.
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/// Returns `None` if there are not enough checkpoints available to reach the
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/// requested checkpoint depth.
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fn root(&self, checkpoint_depth: usize) -> Option<H>;
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/// Obtains an authentication path to the value at the specified position,
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/// as of the tree state corresponding to the given root.
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/// Returns `None` if there is no available authentication path to that
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/// position or if the root does not correspond to a checkpointed
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/// root of the tree.
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fn authentication_path(&self, position: Position, as_of_root: &H) -> Option<Vec<H>>;
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/// Marks the value at the specified position as a value we're no longer
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/// interested in maintaining a witness for. Returns true if successful and
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/// false if we were already not maintaining a witness at this position.
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fn remove_witness(&mut self, position: Position) -> bool;
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/// Creates a new checkpoint for the current tree state. It is valid to
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/// have multiple checkpoints for the same tree state, and each `rewind`
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/// call will remove a single checkpoint.
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fn checkpoint(&mut self);
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/// Rewinds the tree state to the previous checkpoint, and then removes
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/// that checkpoint record. If there are multiple checkpoints at a given
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/// tree state, the tree state will not be altered until all checkpoints
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/// at that tree state have been removed using `rewind`. This function
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/// return false and leave the tree unmodified if no checkpoints exist.
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fn rewind(&mut self) -> bool;
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/// Remove state from the tree that no longer needs to be maintained
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/// because it is associated with checkpoints or witnesses that
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/// have been removed from the tree at positions deeper than those
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/// reachable by calls to `rewind`. It is always safe to implement
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/// this as a no-op operation
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fn garbage_collect(&mut self);
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}
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#[cfg(test)]
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pub(crate) mod tests {
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#![allow(deprecated)]
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use std::collections::BTreeSet;
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use std::fmt::Debug;
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use std::hash::Hasher;
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use std::hash::SipHasher;
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use super::bridgetree::BridgeTree;
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use super::sample::{lazy_root, CompleteTree};
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use super::{Altitude, Hashable, Position, Tree};
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#[test]
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fn position_altitudes() {
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assert_eq!(Position(0).max_altitude(), Altitude(0));
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assert_eq!(Position(1).max_altitude(), Altitude(0));
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assert_eq!(Position(2).max_altitude(), Altitude(1));
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assert_eq!(Position(3).max_altitude(), Altitude(1));
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assert_eq!(Position(4).max_altitude(), Altitude(2));
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assert_eq!(Position(7).max_altitude(), Altitude(2));
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assert_eq!(Position(8).max_altitude(), Altitude(3));
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}
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//
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// Types and utilities for shared example tests.
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//
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#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
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pub(crate) struct SipHashable(pub(crate) u64);
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impl Hashable for SipHashable {
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fn empty_leaf() -> Self {
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SipHashable(0)
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}
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fn combine(_level: Altitude, a: &Self, b: &Self) -> Self {
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let mut hasher = SipHasher::new();
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hasher.write_u64(a.0);
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hasher.write_u64(b.0);
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SipHashable(hasher.finish())
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}
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}
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impl Hashable for String {
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fn empty_leaf() -> Self {
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"_".to_string()
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}
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fn combine(_: Altitude, a: &Self, b: &Self) -> Self {
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a.to_string() + b
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}
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}
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//
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// Shared example tests
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//
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pub(crate) fn check_root_hashes<T: Tree<String>, F: Fn(usize) -> T>(new_tree: F) {
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let mut tree = new_tree(100);
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assert_eq!(tree.root(0).unwrap(), "________________");
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tree.append(&"a".to_string());
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assert_eq!(tree.root(0).unwrap().len(), 16);
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assert_eq!(tree.root(0).unwrap(), "a_______________");
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tree.append(&"b".to_string());
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assert_eq!(tree.root(0).unwrap(), "ab______________");
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tree.append(&"c".to_string());
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assert_eq!(tree.root(0).unwrap(), "abc_____________");
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let mut t = new_tree(100);
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t.append(&"a".to_string());
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t.checkpoint();
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t.witness();
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t.append(&"a".to_string());
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t.append(&"a".to_string());
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t.append(&"a".to_string());
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assert_eq!(t.root(0).unwrap(), "aaaa____________");
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}
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pub(crate) fn check_auth_paths<T: Tree<String> + std::fmt::Debug, F: Fn(usize) -> T>(
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new_tree: F,
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) {
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let mut tree = new_tree(100);
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tree.append(&"a".to_string());
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tree.witness();
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assert_eq!(
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tree.authentication_path(Position::from(0), &tree.root(0).unwrap()),
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Some(vec![
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"_".to_string(),
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"__".to_string(),
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"____".to_string(),
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"________".to_string()
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])
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);
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tree.append(&"b".to_string());
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assert_eq!(
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tree.authentication_path(Position::zero(), &tree.root(0).unwrap()),
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Some(vec![
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"b".to_string(),
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"__".to_string(),
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"____".to_string(),
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"________".to_string()
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])
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);
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tree.append(&"c".to_string());
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tree.witness();
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assert_eq!(
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tree.authentication_path(Position::from(2), &tree.root(0).unwrap()),
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Some(vec![
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"_".to_string(),
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"ab".to_string(),
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"____".to_string(),
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"________".to_string()
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])
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);
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tree.append(&"d".to_string());
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assert_eq!(
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tree.authentication_path(Position::from(2), &tree.root(0).unwrap()),
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Some(vec![
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"d".to_string(),
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"ab".to_string(),
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"____".to_string(),
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"________".to_string()
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])
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);
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tree.append(&"e".to_string());
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assert_eq!(
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tree.authentication_path(Position::from(2), &tree.root(0).unwrap()),
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Some(vec![
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"d".to_string(),
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"ab".to_string(),
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"e___".to_string(),
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"________".to_string()
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])
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);
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let mut tree = new_tree(100);
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tree.append(&"a".to_string());
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tree.witness();
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for c in 'b'..'h' {
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tree.append(&c.to_string());
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}
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tree.witness();
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tree.append(&"h".to_string());
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assert_eq!(
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tree.authentication_path(Position::zero(), &tree.root(0).unwrap()),
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Some(vec![
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"b".to_string(),
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"cd".to_string(),
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"efgh".to_string(),
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"________".to_string()
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])
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);
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let mut tree = new_tree(100);
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tree.append(&"a".to_string());
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tree.witness();
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tree.append(&"b".to_string());
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tree.append(&"c".to_string());
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tree.append(&"d".to_string());
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tree.witness();
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tree.append(&"e".to_string());
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tree.witness();
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tree.append(&"f".to_string());
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tree.witness();
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tree.append(&"g".to_string());
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|
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assert_eq!(
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tree.authentication_path(Position::from(5), &tree.root(0).unwrap()),
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Some(vec![
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"e".to_string(),
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"g_".to_string(),
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"abcd".to_string(),
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"________".to_string()
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])
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);
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let mut tree = new_tree(100);
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for c in 'a'..'l' {
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tree.append(&c.to_string());
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}
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tree.witness();
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tree.append(&'l'.to_string());
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assert_eq!(
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tree.authentication_path(Position::from(10), &tree.root(0).unwrap()),
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Some(vec![
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"l".to_string(),
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"ij".to_string(),
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"____".to_string(),
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"abcdefgh".to_string()
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])
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);
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let mut tree = new_tree(100);
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tree.append(&'a'.to_string());
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tree.witness();
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tree.checkpoint();
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assert!(tree.rewind());
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for c in 'b'..'f' {
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tree.append(&c.to_string());
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}
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tree.witness();
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for c in 'f'..'i' {
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tree.append(&c.to_string());
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}
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|
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assert_eq!(
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tree.authentication_path(Position::zero(), &tree.root(0).unwrap()),
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Some(vec![
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"b".to_string(),
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"cd".to_string(),
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"efgh".to_string(),
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"________".to_string()
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])
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);
|
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|
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let mut tree = new_tree(100);
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tree.append(&'a'.to_string());
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tree.append(&'b'.to_string());
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tree.append(&'c'.to_string());
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tree.witness();
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tree.append(&'d'.to_string());
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tree.append(&'e'.to_string());
|
|
tree.append(&'f'.to_string());
|
|
tree.append(&'g'.to_string());
|
|
tree.witness();
|
|
tree.checkpoint();
|
|
tree.append(&'h'.to_string());
|
|
assert!(tree.rewind());
|
|
|
|
assert_eq!(
|
|
tree.authentication_path(Position::from(2), &tree.root(0).unwrap()),
|
|
Some(vec![
|
|
"d".to_string(),
|
|
"ab".to_string(),
|
|
"efg_".to_string(),
|
|
"________".to_string()
|
|
])
|
|
);
|
|
|
|
let mut tree = new_tree(100);
|
|
tree.append(&'a'.to_string());
|
|
tree.append(&'b'.to_string());
|
|
tree.witness();
|
|
assert_eq!(
|
|
tree.authentication_path(Position::from(0), &tree.root(0).unwrap()),
|
|
None
|
|
);
|
|
|
|
let mut tree = new_tree(100);
|
|
for c in 'a'..'n' {
|
|
tree.append(&c.to_string());
|
|
}
|
|
tree.witness();
|
|
tree.append(&'n'.to_string());
|
|
tree.witness();
|
|
tree.append(&'o'.to_string());
|
|
tree.append(&'p'.to_string());
|
|
|
|
assert_eq!(
|
|
tree.authentication_path(Position::from(12), &tree.root(0).unwrap()),
|
|
Some(vec![
|
|
"n".to_string(),
|
|
"op".to_string(),
|
|
"ijkl".to_string(),
|
|
"abcdefgh".to_string()
|
|
])
|
|
);
|
|
|
|
let ops = ('a'..='l')
|
|
.into_iter()
|
|
.map(|c| Append(c.to_string()))
|
|
.chain(Some(Witness))
|
|
.chain(Some(Append('m'.to_string())))
|
|
.chain(Some(Append('n'.to_string())))
|
|
.chain(Some(Authpath(11usize.into(), 0)))
|
|
.collect::<Vec<_>>();
|
|
|
|
let mut tree = new_tree(100);
|
|
assert_eq!(
|
|
Operation::apply_all(&ops, &mut tree),
|
|
Some((
|
|
Position::from(11),
|
|
vec![
|
|
"k".to_string(),
|
|
"ij".to_string(),
|
|
"mn__".to_string(),
|
|
"abcdefgh".to_string()
|
|
]
|
|
))
|
|
);
|
|
}
|
|
|
|
pub(crate) fn check_checkpoint_rewind<T: Tree<String>, F: Fn(usize) -> T>(new_tree: F) {
|
|
let mut t = new_tree(100);
|
|
assert!(!t.rewind());
|
|
|
|
let mut t = new_tree(100);
|
|
t.checkpoint();
|
|
assert!(t.rewind());
|
|
|
|
let mut t = new_tree(100);
|
|
t.append(&"a".to_string());
|
|
t.checkpoint();
|
|
t.append(&"b".to_string());
|
|
t.witness();
|
|
assert!(t.rewind());
|
|
assert_eq!(Some(Position::from(0)), t.current_position());
|
|
|
|
let mut t = new_tree(100);
|
|
t.append(&"a".to_string());
|
|
t.witness();
|
|
t.checkpoint();
|
|
assert!(t.rewind());
|
|
|
|
let mut t = new_tree(100);
|
|
t.append(&"a".to_string());
|
|
t.checkpoint();
|
|
t.witness();
|
|
t.append(&"a".to_string());
|
|
assert!(t.rewind());
|
|
assert_eq!(Some(Position::from(0)), t.current_position());
|
|
|
|
let mut t = new_tree(100);
|
|
t.append(&"a".to_string());
|
|
t.checkpoint();
|
|
t.checkpoint();
|
|
assert!(t.rewind());
|
|
t.append(&"b".to_string());
|
|
assert!(t.rewind());
|
|
t.append(&"b".to_string());
|
|
assert_eq!(t.root(0).unwrap(), "ab______________");
|
|
}
|
|
|
|
pub(crate) fn check_rewind_remove_witness<T: Tree<String>, F: Fn(usize) -> T>(new_tree: F) {
|
|
let mut tree = new_tree(100);
|
|
tree.append(&"e".to_string());
|
|
tree.witness();
|
|
tree.checkpoint();
|
|
assert!(tree.rewind());
|
|
assert!(tree.remove_witness(0usize.into()));
|
|
|
|
let mut tree = new_tree(100);
|
|
tree.append(&"e".to_string());
|
|
tree.checkpoint();
|
|
tree.witness();
|
|
assert!(tree.rewind());
|
|
assert!(!tree.remove_witness(0usize.into()));
|
|
|
|
let mut tree = new_tree(100);
|
|
tree.append(&"e".to_string());
|
|
tree.witness();
|
|
tree.checkpoint();
|
|
assert!(tree.remove_witness(0usize.into()));
|
|
assert!(tree.rewind());
|
|
assert!(tree.remove_witness(0usize.into()));
|
|
|
|
let mut tree = new_tree(100);
|
|
tree.append(&"e".to_string());
|
|
tree.witness();
|
|
assert!(tree.remove_witness(0usize.into()));
|
|
tree.checkpoint();
|
|
assert!(tree.rewind());
|
|
assert!(!tree.remove_witness(0usize.into()));
|
|
|
|
let mut tree = new_tree(100);
|
|
tree.append(&"a".to_string());
|
|
assert!(!tree.remove_witness(0usize.into()));
|
|
tree.checkpoint();
|
|
assert!(tree.witness().is_some());
|
|
assert!(tree.rewind());
|
|
|
|
let mut tree = new_tree(100);
|
|
tree.append(&"a".to_string());
|
|
tree.checkpoint();
|
|
assert!(tree.witness().is_some());
|
|
assert!(tree.remove_witness(0usize.into()));
|
|
assert!(tree.rewind());
|
|
assert!(!tree.remove_witness(0usize.into()));
|
|
|
|
// The following check_operations tests cover errors where the
|
|
// test framework itself previously did not correctly handle
|
|
// chain state restoration.
|
|
|
|
let samples = vec![
|
|
vec![append("x"), Checkpoint, Witness, Rewind, unwitness(0)],
|
|
vec![
|
|
append("d"),
|
|
Checkpoint,
|
|
Witness,
|
|
unwitness(0),
|
|
Rewind,
|
|
unwitness(0),
|
|
],
|
|
vec![
|
|
append("o"),
|
|
Checkpoint,
|
|
Witness,
|
|
Checkpoint,
|
|
unwitness(0),
|
|
Rewind,
|
|
Rewind,
|
|
],
|
|
vec![
|
|
append("s"),
|
|
Witness,
|
|
append("m"),
|
|
Checkpoint,
|
|
unwitness(0),
|
|
Rewind,
|
|
unwitness(0),
|
|
unwitness(0),
|
|
],
|
|
];
|
|
|
|
for (i, sample) in samples.iter().enumerate() {
|
|
let result = check_operations(sample);
|
|
assert!(
|
|
matches!(result, Ok(())),
|
|
"Reference/Test mismatch at index {}: {:?}",
|
|
i,
|
|
result
|
|
);
|
|
}
|
|
}
|
|
|
|
//
|
|
// Types and utilities for cross-verification property tests
|
|
//
|
|
|
|
#[derive(Clone)]
|
|
pub struct CombinedTree<H: Hashable + Ord, const DEPTH: u8> {
|
|
inefficient: CompleteTree<H>,
|
|
efficient: BridgeTree<H, DEPTH>,
|
|
}
|
|
|
|
impl<H: Hashable + Ord + Clone, const DEPTH: u8> CombinedTree<H, DEPTH> {
|
|
pub fn new() -> Self {
|
|
CombinedTree {
|
|
inefficient: CompleteTree::new(DEPTH.into(), 100),
|
|
efficient: BridgeTree::new(100),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<H: Hashable + Ord + Clone + Debug, const DEPTH: u8> Tree<H> for CombinedTree<H, DEPTH> {
|
|
fn append(&mut self, value: &H) -> bool {
|
|
let a = self.inefficient.append(value);
|
|
let b = self.efficient.append(value);
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn root(&self, checkpoint_depth: usize) -> Option<H> {
|
|
let a = self.inefficient.root(checkpoint_depth);
|
|
let b = self.efficient.root(checkpoint_depth);
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn current_position(&self) -> Option<Position> {
|
|
let a = self.inefficient.current_position();
|
|
let b = self.efficient.current_position();
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn current_leaf(&self) -> Option<&H> {
|
|
let a = self.inefficient.current_leaf();
|
|
let b = self.efficient.current_leaf();
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn get_witnessed_leaf(&self, position: Position) -> Option<&H> {
|
|
let a = self.inefficient.get_witnessed_leaf(position);
|
|
let b = self.efficient.get_witnessed_leaf(position);
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn witness(&mut self) -> Option<Position> {
|
|
let a = self.inefficient.witness();
|
|
let b = self.efficient.witness();
|
|
assert_eq!(a, b);
|
|
let apos = self.inefficient.witnessed_positions();
|
|
let bpos = self.efficient.witnessed_positions();
|
|
assert_eq!(apos, bpos);
|
|
a
|
|
}
|
|
|
|
fn witnessed_positions(&self) -> BTreeSet<Position> {
|
|
let a = self.inefficient.witnessed_positions();
|
|
let b = self.efficient.witnessed_positions();
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn authentication_path(&self, position: Position, as_of_root: &H) -> Option<Vec<H>> {
|
|
let a = self.inefficient.authentication_path(position, as_of_root);
|
|
let b = self.efficient.authentication_path(position, as_of_root);
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn remove_witness(&mut self, position: Position) -> bool {
|
|
let a = self.inefficient.remove_witness(position);
|
|
let b = self.efficient.remove_witness(position);
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn checkpoint(&mut self) {
|
|
self.inefficient.checkpoint();
|
|
self.efficient.checkpoint();
|
|
}
|
|
|
|
fn rewind(&mut self) -> bool {
|
|
let a = self.inefficient.rewind();
|
|
let b = self.efficient.rewind();
|
|
assert_eq!(a, b);
|
|
a
|
|
}
|
|
|
|
fn garbage_collect(&mut self) {
|
|
self.inefficient.garbage_collect();
|
|
self.efficient.garbage_collect();
|
|
}
|
|
}
|
|
|
|
//
|
|
// Operations
|
|
//
|
|
|
|
#[derive(Clone, Debug)]
|
|
pub enum Operation<A> {
|
|
Append(A),
|
|
CurrentPosition,
|
|
CurrentLeaf,
|
|
Witness,
|
|
WitnessedLeaf(Position),
|
|
WitnessedPositions,
|
|
Unwitness(Position),
|
|
Checkpoint,
|
|
Rewind,
|
|
Authpath(Position, usize),
|
|
GarbageCollect,
|
|
}
|
|
|
|
use Operation::*;
|
|
|
|
fn append(x: &str) -> Operation<String> {
|
|
Operation::Append(x.to_string())
|
|
}
|
|
|
|
fn unwitness(pos: usize) -> Operation<String> {
|
|
Operation::Unwitness(Position::from(pos))
|
|
}
|
|
|
|
fn authpath(pos: usize, depth: usize) -> Operation<String> {
|
|
Operation::Authpath(Position::from(pos), depth)
|
|
}
|
|
|
|
impl<H: Hashable> Operation<H> {
|
|
pub fn apply<T: Tree<H>>(&self, tree: &mut T) -> Option<(Position, Vec<H>)> {
|
|
match self {
|
|
Append(a) => {
|
|
assert!(tree.append(a), "append failed");
|
|
None
|
|
}
|
|
CurrentPosition => None,
|
|
CurrentLeaf => None,
|
|
Witness => {
|
|
assert!(tree.witness().is_some(), "witness failed");
|
|
None
|
|
}
|
|
WitnessedLeaf(_) => None,
|
|
WitnessedPositions => None,
|
|
Unwitness(p) => {
|
|
assert!(tree.remove_witness(*p), "remove witness failed");
|
|
None
|
|
}
|
|
Checkpoint => {
|
|
tree.checkpoint();
|
|
None
|
|
}
|
|
Rewind => {
|
|
assert!(tree.rewind(), "rewind failed");
|
|
None
|
|
}
|
|
Authpath(p, d) => tree
|
|
.root(*d)
|
|
.and_then(|root| tree.authentication_path(*p, &root))
|
|
.map(|xs| (*p, xs)),
|
|
GarbageCollect => None,
|
|
}
|
|
}
|
|
|
|
pub fn apply_all<T: Tree<H>>(
|
|
ops: &[Operation<H>],
|
|
tree: &mut T,
|
|
) -> Option<(Position, Vec<H>)> {
|
|
let mut result = None;
|
|
for op in ops {
|
|
result = op.apply(tree);
|
|
}
|
|
result
|
|
}
|
|
}
|
|
|
|
pub(crate) fn compute_root_from_auth_path<H: Hashable>(
|
|
value: H,
|
|
position: Position,
|
|
path: &[H],
|
|
) -> H {
|
|
let mut cur = value;
|
|
let mut lvl = Altitude::zero();
|
|
for (i, v) in path
|
|
.iter()
|
|
.enumerate()
|
|
.map(|(i, v)| (((<usize>::from(position) >> i) & 1) == 1, v))
|
|
{
|
|
if i {
|
|
cur = H::combine(lvl, v, &cur);
|
|
} else {
|
|
cur = H::combine(lvl, &cur, v);
|
|
}
|
|
lvl = lvl + 1;
|
|
}
|
|
cur
|
|
}
|
|
|
|
#[test]
|
|
fn test_compute_root_from_auth_path() {
|
|
let expected = SipHashable::combine(
|
|
<Altitude>::from(2),
|
|
&SipHashable::combine(
|
|
Altitude::one(),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(0), &SipHashable(1)),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(2), &SipHashable(3)),
|
|
),
|
|
&SipHashable::combine(
|
|
Altitude::one(),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(4), &SipHashable(5)),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(6), &SipHashable(7)),
|
|
),
|
|
);
|
|
|
|
assert_eq!(
|
|
compute_root_from_auth_path::<SipHashable>(
|
|
SipHashable(0),
|
|
Position::zero(),
|
|
&[
|
|
SipHashable(1),
|
|
SipHashable::combine(Altitude::zero(), &SipHashable(2), &SipHashable(3)),
|
|
SipHashable::combine(
|
|
Altitude::one(),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(4), &SipHashable(5)),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(6), &SipHashable(7))
|
|
)
|
|
]
|
|
),
|
|
expected
|
|
);
|
|
|
|
assert_eq!(
|
|
compute_root_from_auth_path(
|
|
SipHashable(4),
|
|
<Position>::from(4),
|
|
&[
|
|
SipHashable(5),
|
|
SipHashable::combine(Altitude::zero(), &SipHashable(6), &SipHashable(7)),
|
|
SipHashable::combine(
|
|
Altitude::one(),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(0), &SipHashable(1)),
|
|
&SipHashable::combine(Altitude::zero(), &SipHashable(2), &SipHashable(3))
|
|
)
|
|
]
|
|
),
|
|
expected
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn test_auth_path_consistency() {
|
|
let samples = vec![
|
|
// Reduced examples
|
|
vec![
|
|
append("a"),
|
|
append("b"),
|
|
Checkpoint,
|
|
Witness,
|
|
authpath(0, 1),
|
|
],
|
|
vec![
|
|
append("c"),
|
|
append("d"),
|
|
Witness,
|
|
Checkpoint,
|
|
authpath(1, 1),
|
|
],
|
|
vec![
|
|
append("e"),
|
|
Checkpoint,
|
|
Witness,
|
|
append("f"),
|
|
authpath(0, 1),
|
|
],
|
|
vec![
|
|
append("g"),
|
|
Witness,
|
|
Checkpoint,
|
|
unwitness(0),
|
|
append("h"),
|
|
authpath(0, 0),
|
|
],
|
|
vec![
|
|
append("i"),
|
|
Checkpoint,
|
|
Witness,
|
|
unwitness(0),
|
|
append("j"),
|
|
authpath(0, 0),
|
|
],
|
|
vec![
|
|
append("i"),
|
|
Witness,
|
|
append("j"),
|
|
Checkpoint,
|
|
append("k"),
|
|
authpath(0, 1),
|
|
],
|
|
vec![
|
|
append("l"),
|
|
Checkpoint,
|
|
Witness,
|
|
Checkpoint,
|
|
append("m"),
|
|
Checkpoint,
|
|
authpath(0, 2),
|
|
],
|
|
vec![Checkpoint, append("n"), Witness, authpath(0, 1)],
|
|
vec![
|
|
append("a"),
|
|
Witness,
|
|
Checkpoint,
|
|
unwitness(0),
|
|
Checkpoint,
|
|
append("b"),
|
|
authpath(0, 1),
|
|
],
|
|
vec![
|
|
append("a"),
|
|
Witness,
|
|
append("b"),
|
|
unwitness(0),
|
|
Checkpoint,
|
|
authpath(0, 0),
|
|
],
|
|
vec![
|
|
append("a"),
|
|
Witness,
|
|
Checkpoint,
|
|
unwitness(0),
|
|
Checkpoint,
|
|
Rewind,
|
|
append("b"),
|
|
authpath(0, 0),
|
|
],
|
|
vec![
|
|
append("a"),
|
|
Witness,
|
|
Checkpoint,
|
|
Checkpoint,
|
|
Rewind,
|
|
append("a"),
|
|
unwitness(0),
|
|
authpath(0, 1),
|
|
],
|
|
// Unreduced examples
|
|
vec![
|
|
append("o"),
|
|
append("p"),
|
|
Witness,
|
|
append("q"),
|
|
Checkpoint,
|
|
unwitness(1),
|
|
authpath(1, 1),
|
|
],
|
|
vec![
|
|
append("r"),
|
|
append("s"),
|
|
append("t"),
|
|
Witness,
|
|
Checkpoint,
|
|
unwitness(2),
|
|
Checkpoint,
|
|
authpath(2, 2),
|
|
],
|
|
vec![
|
|
append("u"),
|
|
Witness,
|
|
append("v"),
|
|
append("w"),
|
|
Checkpoint,
|
|
unwitness(0),
|
|
append("x"),
|
|
Checkpoint,
|
|
Checkpoint,
|
|
authpath(0, 3),
|
|
],
|
|
];
|
|
|
|
for (i, sample) in samples.iter().enumerate() {
|
|
let result = check_operations(sample);
|
|
assert!(
|
|
matches!(result, Ok(())),
|
|
"Reference/Test mismatch at index {}: {:?}",
|
|
i,
|
|
result
|
|
);
|
|
}
|
|
}
|
|
|
|
// These check_operations tests cover errors where the test framework itself previously did not
|
|
// correctly handle chain state restoration.
|
|
#[test]
|
|
fn test_rewind_remove_witness_consistency() {
|
|
let samples = vec![
|
|
vec![append("x"), Checkpoint, Witness, Rewind, unwitness(0)],
|
|
vec![
|
|
append("d"),
|
|
Checkpoint,
|
|
Witness,
|
|
unwitness(0),
|
|
Rewind,
|
|
unwitness(0),
|
|
],
|
|
vec![
|
|
append("o"),
|
|
Checkpoint,
|
|
Witness,
|
|
Checkpoint,
|
|
unwitness(0),
|
|
Rewind,
|
|
Rewind,
|
|
],
|
|
vec![
|
|
append("s"),
|
|
Witness,
|
|
append("m"),
|
|
Checkpoint,
|
|
unwitness(0),
|
|
Rewind,
|
|
unwitness(0),
|
|
unwitness(0),
|
|
],
|
|
];
|
|
for (i, sample) in samples.iter().enumerate() {
|
|
let result = check_operations(sample);
|
|
assert!(
|
|
matches!(result, Ok(())),
|
|
"Reference/Test mismatch at index {}: {:?}",
|
|
i,
|
|
result
|
|
);
|
|
}
|
|
}
|
|
|
|
use proptest::prelude::*;
|
|
|
|
pub fn arb_operation<G: Strategy + Clone>(
|
|
item_gen: G,
|
|
pos_gen: impl Strategy<Value = usize> + Clone,
|
|
) -> impl Strategy<Value = Operation<G::Value>>
|
|
where
|
|
G::Value: Clone + 'static,
|
|
{
|
|
prop_oneof![
|
|
item_gen.prop_map(Operation::Append),
|
|
Just(Operation::Witness),
|
|
prop_oneof![
|
|
Just(Operation::CurrentLeaf),
|
|
Just(Operation::CurrentPosition),
|
|
Just(Operation::WitnessedPositions),
|
|
],
|
|
Just(Operation::GarbageCollect),
|
|
pos_gen
|
|
.clone()
|
|
.prop_map(|i| Operation::WitnessedLeaf(Position::from(i))),
|
|
pos_gen
|
|
.clone()
|
|
.prop_map(|i| Operation::Unwitness(Position::from(i))),
|
|
Just(Operation::Checkpoint),
|
|
Just(Operation::Rewind),
|
|
pos_gen.prop_flat_map(|i| (0usize..10)
|
|
.prop_map(move |depth| Operation::Authpath(Position::from(i), depth))),
|
|
]
|
|
}
|
|
|
|
pub fn apply_operation<H, T: Tree<H>>(tree: &mut T, op: Operation<H>) {
|
|
match op {
|
|
Append(value) => {
|
|
tree.append(&value);
|
|
}
|
|
Witness => {
|
|
tree.witness();
|
|
}
|
|
Unwitness(position) => {
|
|
tree.remove_witness(position);
|
|
}
|
|
Checkpoint => {
|
|
tree.checkpoint();
|
|
}
|
|
Rewind => {
|
|
tree.rewind();
|
|
}
|
|
CurrentPosition => {}
|
|
CurrentLeaf => {}
|
|
Authpath(_, _) => {}
|
|
WitnessedLeaf(_) => {}
|
|
WitnessedPositions => {}
|
|
GarbageCollect => {}
|
|
}
|
|
}
|
|
|
|
fn check_operations<H: Hashable + Ord + Clone + Debug>(
|
|
ops: &[Operation<H>],
|
|
) -> Result<(), TestCaseError> {
|
|
const DEPTH: u8 = 4;
|
|
let mut tree = CombinedTree::<H, DEPTH>::new();
|
|
|
|
let mut tree_size = 0;
|
|
let mut tree_values: Vec<H> = vec![];
|
|
// the number of leaves in the tree at the time that a checkpoint is made
|
|
let mut tree_checkpoints: Vec<usize> = vec![];
|
|
|
|
for op in ops {
|
|
prop_assert_eq!(tree_size, tree_values.len());
|
|
match op {
|
|
Append(value) => {
|
|
if tree.append(value) {
|
|
prop_assert!(tree_size < (1 << DEPTH));
|
|
tree_size += 1;
|
|
tree_values.push(value.clone());
|
|
} else {
|
|
prop_assert_eq!(tree_size, 1 << DEPTH);
|
|
}
|
|
}
|
|
CurrentPosition => {
|
|
if let Some(pos) = tree.current_position() {
|
|
prop_assert!(tree_size > 0);
|
|
prop_assert_eq!(tree_size - 1, pos.into());
|
|
}
|
|
}
|
|
CurrentLeaf => {
|
|
prop_assert_eq!(tree_values.last(), tree.current_leaf());
|
|
}
|
|
Witness => {
|
|
if tree.witness().is_some() {
|
|
prop_assert!(tree_size != 0);
|
|
} else {
|
|
prop_assert_eq!(tree_size, 0);
|
|
}
|
|
}
|
|
WitnessedLeaf(position) => {
|
|
if tree.get_witnessed_leaf(*position).is_some() {
|
|
prop_assert!(<usize>::from(*position) < tree_size);
|
|
}
|
|
}
|
|
Unwitness(position) => {
|
|
tree.remove_witness(*position);
|
|
}
|
|
WitnessedPositions => {}
|
|
Checkpoint => {
|
|
tree_checkpoints.push(tree_size);
|
|
tree.checkpoint();
|
|
}
|
|
Rewind => {
|
|
if tree.rewind() {
|
|
prop_assert!(!tree_checkpoints.is_empty());
|
|
let checkpointed_tree_size = tree_checkpoints.pop().unwrap();
|
|
tree_values.truncate(checkpointed_tree_size);
|
|
tree_size = checkpointed_tree_size;
|
|
}
|
|
}
|
|
Authpath(position, depth) => {
|
|
if let Some(path) = tree
|
|
.root(*depth)
|
|
.and_then(|r| tree.authentication_path(*position, &r))
|
|
{
|
|
let value: H = tree_values[<usize>::from(*position)].clone();
|
|
let tree_root = tree.root(*depth);
|
|
|
|
if tree_checkpoints.len() >= *depth {
|
|
let mut extended_tree_values = tree_values.clone();
|
|
if *depth > 0 {
|
|
// prune the tree back to the checkpointed size.
|
|
if let Some(checkpointed_tree_size) =
|
|
tree_checkpoints.get(tree_checkpoints.len() - depth)
|
|
{
|
|
extended_tree_values.truncate(*checkpointed_tree_size);
|
|
}
|
|
}
|
|
// extend the tree with empty leaves until it is full
|
|
extended_tree_values.resize(1 << DEPTH, H::empty_leaf());
|
|
|
|
// compute the root
|
|
let expected_root = lazy_root::<H>(extended_tree_values);
|
|
prop_assert_eq!(&tree_root.unwrap(), &expected_root);
|
|
|
|
prop_assert_eq!(
|
|
&compute_root_from_auth_path(value, *position, &path),
|
|
&expected_root
|
|
);
|
|
}
|
|
}
|
|
}
|
|
GarbageCollect => {}
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
proptest! {
|
|
#![proptest_config(ProptestConfig::with_cases(100000))]
|
|
|
|
#[test]
|
|
fn check_randomized_u64_ops(
|
|
ops in proptest::collection::vec(
|
|
arb_operation((0..32u64).prop_map(SipHashable), 0usize..100),
|
|
1..100
|
|
)
|
|
) {
|
|
check_operations(&ops)?;
|
|
}
|
|
|
|
#[test]
|
|
fn check_randomized_str_ops(
|
|
ops in proptest::collection::vec(
|
|
arb_operation((97u8..123).prop_map(|c| char::from(c).to_string()), 0usize..100),
|
|
1..100
|
|
)
|
|
) {
|
|
check_operations::<String>(&ops)?;
|
|
}
|
|
}
|
|
}
|