incrementalmerkletree/incrementalmerkletree/CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Rust's notion of Semantic Versioning.

[Unreleased]

Removed

• The bridgetree module has been moved out a to a separate bridgetree crate.

[0.3.0] - 2022-05-10

Added

• incrementalmerkletree::bridgetree:
  • Checkpoint::witnessed returns the set of positions that have been marked with BridgeTree::witness while this checkpoint was the current checkpoint.

Changed

• incrementalmerkletree:
  • Tree::authentication_path has been changed to take an as_of_root parameter. This allows computation of the authentication path as of previous tree states, in addition to the previous behavior which only allowed computation of the path as of the most recent tree state. The provided as_of_root value must be equal to either the current root of the tree, or to the root of the tree at a previous checkpoint that contained a note at the given position.

Removed

• incrementalmerkletree::bridgetree:
  • Checkpoint::rewrite_indices was an internal utility method that had inadvertently been made a part of the public API.

[0.3.0-beta.2] - 2022-04-06

Added

• incrementalmerkletree:
  • Tree::get_witnessed_leaf, to allow a user to query for the leaf value of witnessed leaves by their position in the tree.
  • Tree::witnessed_positions, to allow a user to query for all positions that have been witnessed.
  • Tree::garbage_collect, to prune checkpoint and removed witness information that is no longer reachable by rewinds of the tree.
• incrementalmerkletree::bridgetree:
  • NonEmptyFrontier::current_leaf
  • BridgeTree::from_frontier
  • BridgeTree::check_consistency

Changed

• incrementalmerkletree:
  • The Tree trait has substantial changes in this release. Hashes are no longer used in identifying nodes when generating authentication paths and removing witnesses; instead, these operations now use position information exclusively.
  • Tree::authentication_path and Tree::remove_witness have both been changed to only take a position parameter, instead of both the leaf value and the position.
  • Tree::current_leaf and Tree::witness have both been changed to only return the leaf value, instead of both the leaf value and the position.
• incrementalmerkletree::bridgetree:
  • The type of BridgeTree::saved and Checkpoint::forgotten have been changed from BTreeMap<(Position, H), usize> to BTreeMap<Position, usize>. This change is also reflected in the rturn type of the BridgeTree::witnessed_indices method.
  • The Checkpoint type is no longer parameterized by H.
  • BridgeTree::bridges has been split into two parts:
    • BridgeTree::prior_bridges now tracks past bridges not including the current frontier.
    • BridgeTree::current_bridge now tracks current mutable frontier.
  • The signature of BridgeTree::from_parts has been modified to reflect these changes.

Removed

• incrementalmerkletree:
  • Tree::is_witnessed (use Tree::get_witnessed_leaf(...).is_some() instead).
  • The recording / playback infrastructure, which was unused and added unnecessary complexity:
    • The Tree::Recording associated type.
    • Tree::{recording, play}
    • Recording
• Tree::is_witnessed has been removed (use Tree::get_witnessed_leaf(...).is_some() instead).

Fixed

• A bug in BridgeTree::garbage_collect that caused garbage collection to in some cases incorrectly rewrite checkpointed bridge lengths, resulting in a condition where a rewind could panic after a GC operation.

[0.3.0-beta.1] - 2022-03-22

Added

• incrementalmerkletree:
  • New trait impls
    • impl From<Position> for usize
    • impl Add<usize> for Position
    • impl AddAssign<usize> for Position
    • impl TryFrom<u64> for Position
    • impl Hash for Position
  • New trait methods:
    • Tree::current_leaf, which returns the position of the latest note appended to the tree along with the leaf value, if any.
    • Tree::current_position, which returns the position of the latest note appended to the tree, if any.
    • Tree::is_witnessed, which returns a boolean value indicating whether a leaf value has been marked for later construction of an authentication path at a specified position in the tree.
• incrementalmerkletree::bridgetree:
  • MerkleBridge::position, which returns the position of the tip of the frontier.
  • MerkleBridge::current_leaf, which returns the leaf value most recently appended to the frontier.
  • Leaf::value, which returns the value of the leaf by reference.
  • impl {PartialEq, Eq} for {AuthFragment, MerkleBridge, BridgeTreeError}
  • Various constructor and accessor methods for Checkpoint to facilitate serialization:
    • Checkpoint::{from_parts, at_length}
    • Checkpoint::{bridges_len, is_witnessed, forgotten}
    • Checkpoint::rewrite_indices
  • BridgeTree::witnessed_indices
  • BridgeTree::garbage_collect, which prunes data for removed witnesses and inaccessable checkpoints beyond the max rewind depth.

Changed

• incrementalmerkletree:
  • Position now wraps a usize rather than a u64, affecting its layout (as exposed by repr(transparent)).
  • The following methods now take an additional Position argument to support cases where leaf values may appear at multiple positions in the tree:
    • Tree::authentication_path
    • Tree::remove_witness
  • Tree::witness now returns a tuple of the witnessed position and leaf hash, or None if the tree is empty, instead of a boolean value.
• incrementalmerkletree::bridgetree:
  • Most MerkleBridge methods now require H: Ord.
  • Changed the return type of MerkleBridge::auth_fragments from HashMap<usize, AuthFragment> to BTreeMap<Position, AuthFragment>; the saved argument to BridgeTree::from_parts is similarly altered.
  • MerkleBridge::successor now takes a boolean argument for tracking the most recently appended leaf, instead of the previous cur_idx argument.
  • Checkpoint is now a struct, rather than an enum type, and contains information about witnessed nodes that have been marked for removal since the last checkpoint.
  • BridgeTree now requires an Ord constraint for its leaf type, rather than a Hash constraint.

Removed

• incrementalmerkletree:
  • Position::increment
  • impl TryFrom<Position> for usize (use the From impl instead).
• incrementalmerkletree::bridgetree:
  • Leaf::into_value (use Leaf::value instead).
  • MerkleBridge::leaf_value (use MerkleBridge::current_leaf instead).
  • H: Clone bound on NonEmptyFrontier::<H>::leaf_value.
  • BridgeTree::witnessable_leaves (use BridgeTree::witnessed_indices instead).

[0.2.0] - 2022-03-22

v0.2.0 is essentially a complete rewrite relative to v0.1.0, and should be considered the first usable release.

[0.1.0] - 2021-06-23

Initial release!