# Changelog
All notable changes to this library will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this library adheres to Rust's notion of
[Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [Unreleased]
### Added
- `zcash_primitives::sapling::redjubjub::PublicKey::verify_with_zip216`, for
  controlling how RedJubjub signatures are validated. `PublicKey::verify` has
  been altered to always use post-ZIP 216 validation rules.
- `zcash_primitives::transaction::Builder::with_progress_notifier`, for setting
  a notification channel on which transaction build progress updates will be
  sent.
- `zcash_primitives::transaction::Txid::{read, write, from_bytes}`
- `zcash_primitives::sapling::NoteValue` a typesafe wrapper for Sapling note values.
- `zcash_primitives::consensus::BranchId::{height_range, height_bounds}` functions
  to provide range values for branch active heights.
- `zcash_primitives::consensus::NetworkUpgrade::Nu5` value representing the Nu5 upgrade.
- `zcash_primitives::consensus::BranchId::Nu5` value representing the Nu5 consensus branch.
- New modules under `zcash_primitives::transaction::components` for building parts of
  transactions:
  - `sapling::builder` for Sapling transaction components.
  - `transparent::builder` for transparent transaction components.
  - `tze::builder` for TZE transaction components.
  - `orchard` parsing and serialization for Orchard transaction components.
- `zcash_primitives::transaction::Authorization` a trait representing a type-level
  record of authorization types that correspond to signatures, witnesses, and
  proofs for each Zcash sub-protocol (transparent, Sprout, Sapling, TZE, and
  Orchard). This type makes it possible to encode a type-safe state machine
  for the application of authorizing data to a transaction; implementations of
  this trait represent different states of the authorization process.
- New bundle types under the `zcash_primitives::transaction` submodules, one for 
  each Zcash sub-protocol. These are now used instead of bare fields 
  within the `TransactionData` type.
  - `components::sapling::Bundle` bundle of
    Sapling transaction elements. This new struct is parameterized by a
    type bounded on a newly added `sapling::Authorization` trait which
    is used to enable static reasoning about the state of Sapling proofs and
    authorizing data, as described above.
  - `components::transparent::Bundle` bundle of
    transparent transaction elements. This new struct is parameterized by a
    type bounded on a newly added `transparent::Authorization` trait which
    is used to enable static reasoning about the state of transparent witness
    data, as described above.
  - `components::tze::Bundle` bundle of TZE
    transaction elements. This new struct is parameterized by a
    type bounded on a newly added `tze::Authorization` trait which
    is used to enable static reasoning about the state of TZE witness
    data, as described above.

### Changed
- MSRV is now 1.51.0.
- The following modules and helpers have been moved into
  `zcash_primitives::sapling`:
  - `zcash_primitives::group_hash`
  - `zcash_primitives::keys`
  - `zcash_primitives::pedersen_hash`
  - `zcash_primitives::primitives::*` (moved into `zcash_primitives::sapling`)
  - `zcash_primitives::prover`
  - `zcash_primitives::redjubjub`
  - `zcash_primitives::util::{hash_to_scalar, generate_random_rseed}`
- Renamed `zcash_primitives::transaction::components::JSDescription` to
  `JsDescription` (matching Rust naming conventions).
- `zcash_primitives::transaction::TxId` contents is now private.
- Renamed `zcash_primitives::transaction::components::tze::hash` to
  `zcash_primitives::transaction::components::tze::txid`
- `zcash_primitives::transaction::components::tze::TzeOutPoint` constructor
  now taxes a TxId rather than a raw byte array.
- `zcash_primitives::transaction::components::Amount` addition, subtraction,
  and summation now return `Option` rather than panicing on overflow.
- `zcash_primitives::transaction::builder`:
  - `Error` has been modified to wrap the error types produced by its child
    builders.
  - `Builder::build` no longer takes a consensus branch ID parameter. The
    builder now selects the correct consensus branch ID for the given target
    height.
- The `zcash_primitives::transaction::TransactionData` struct has been modified
  such that it now contains common header information, and then contains
  a separate `Bundle` value for each sub-protocol (transparent, Sprout, Sapling,
  and TZE) and an Orchard bundle value has been added. `TransactionData` is now
  parameterized by a type bounded on the newly added
  `zcash_primitives::transaction::Authorization` trait. This bound has been
  propagated to the individual transaction builders, such that the authorization
  state of a transaction is clearly represented in the type and the presence
  or absence of witness and/or proof data is statically known, instead of being only
  determined at runtime via the presence or absence of `Option`al values.
- `zcash_primitives::transaction::components::sapling` parsing and serialization
  have been adapted for use with the new `sapling::Bundle` type.
- `zcash_primitives::transaction::Transaction` parsing and serialization
  have been adapted for use with the new `TransactionData` organization.
- Generators for property testing have been moved out of the main transaction
  module such that they are now colocated in the modules with the types
  that they generate.
- The `ephemeral_key` field of `OutputDescription` has had its type changed from
  `jubjub::ExtendedPoint` to `zcash_note_encryption::EphemeralKeyBytes`.
- The `epk: jubjub::ExtendedPoint` field of `CompactOutputDescription ` has been
  replaced by `ephemeral_key: zcash_note_encryption::EphemeralKeyBytes`.

## [0.5.0] - 2021-03-26
### Added
- Support for implementing candidate ZIPs before they have been selected for a
  network upgrade, behind the `zfuture` feature flag.
  - At runtime, these ZIPs are gated behind the new `NetworkUpgrade::ZFuture`
    enum case, which is inaccessible without the `zfuture` feature flag. This
    pseudo-NU can be enabled for private testing using a custom implementation
    of the `Parameters` trait.
- New structs and methods:
  - `zcash_primitives::consensus`:
    - `BlockHeight`
    - New methods on the `Parameters` trait:
      - `coin_type`
      - `hrp_sapling_extended_spending_key`
      - `hrp_sapling_extended_full_viewing_key`
      - `hrp_sapling_payment_address`
      - `b58_pubkey_address_prefix`
      - `b58_script_address_prefix`
    - The `Network` enum, which enables code to be generic over the network type
      at runtime.
  - `zcash_primitives::memo`:
    - `MemoBytes`, a minimal wrapper around the memo bytes, that only imposes
      the existence of null-padding for shorter memos. `MemoBytes` is guaranteed
      to be round-trip encodable (modulo null padding).
    - `Memo`, an enum that implements the memo field format defined in
      [ZIP 302](https://zips.z.cash/zip-0302). It can be converted to and from
      `MemoBytes`.
  - `zcash_primitives::primitives::Nullifier` struct.
  - `zcash_primitives::transaction`:
    - `TxVersion` enum, representing the set of valid transaction format
      versions.
    - `SignableInput` enum, encapsulating per-input data used when
      creating transaction signatures.
  - `zcash_primitives::primitives::SaplingIvk`, a newtype wrapper around `jubjub::Fr`
    values that are semantically Sapling incoming viewing keys.
- Test helpers, behind the `test-dependencies` feature flag:
  - `zcash_primitives::prover::mock::MockTxProver`, for building transactions in
    tests without creating proofs.
  - `zcash_primitives::transaction::Builder::test_only_new_with_rng` constructor
    which accepts a non-`CryptoRng` randomness source (for e.g. deterministic
    tests).
  - `proptest` APIs for generating arbitrary Zcash types.
- New constants:
  - `zcash_primitives::consensus`:
    - `H0`, the height of the genesis block.
    - `MAIN_NETWORK`
    - `TEST_NETWORK`
  - `zcash_primitives::constants::{mainnet, testnet, regtest}` modules,
    containing network-specific constants.
  - `zcash_primitives::note_encryption`:
    - `ENC_CIPHERTEXT_SIZE`
    - `OUT_CIPHERTEXT_SIZE`
  - `zcash_primitives::transaction::components::amount`:
    - `COIN`
    - `MAX_MONEY`
- More implementations of standard traits:
  - `zcash_primitives::consensus`:
    - `Parameters: Clone`
    - `MainNetwork: PartialEq`
    - `TestNetwork: PartialEq`
  - `zcash_primitives::legacy`:
    - `Script: PartialEq`
    - `TransparentAddress: Clone + PartialOrd + Hash`
  - `zcash_primitives::redjubjub::PublicKey: Clone`
  - `zcash_primitives::transaction`:
    - `Transaction: Clone`
    - `TransactionData: Clone + Default`
    - `components::Amount: Eq + PartialOrd + Ord`
    - `components::TxIn: Clone + PartialEq`
    - `components::TxOut: PartialEq`
    - `components::SpendDescription: Clone`
    - `components::OutputDescription: Clone`
    - `components::SproutProof: Clone`
    - `components::JSDescription: Clone`
  - `zcash_primitives::zip32::DiversifierIndex: Default`

### Changed
- MSRV is now 1.47.0.
- Trial decryption using the APIs in `zcash_primitives::note_encryption` is now
  over 60% faster at detecting which notes are relevant.
  - Part of this improvement was achieved by changing the APIs to take `epk` as
    a `&jubjub::ExtendedPoint` instead of a `&SubgroupPoint`.
- Various APIs now take the network parameters as an explicit variable instead
  of a type parameter:
  - `zcash_primitives::consensus::BranchId::for_height`
  - The `zcash_primitives::note_encryption` APIs.
  - `zcash_primitives::transaction::builder`:
    - `SaplingOutput::new`
    - `Builder::new`
    - `Builder::new_with_rng`
  - `Parameters::activation_height` and `Parameters::is_nu_active` now take
    `&self`.
- `zcash_primitives::merkle_tree::CommitmentTree::new` has been renamed to
  `CommitmentTree::empty`.
- `zcash_primitives::note_encryption`:
  - `SaplingNoteEncryption::new` now takes `MemoBytes`.
  - The following APIs now return `MemoBytes`:
    - `try_sapling_note_decryption`
    - `try_sapling_output_recovery`
    - `try_sapling_output_recovery_with_ock`
- `zcash_primitives::primitives::SaplingIvk` is now used where functions
  previously used undistinguished `jubjub::Fr` values; this affects Sapling
  note decryption and handling of IVKs by the wallet backend code.
- `zcash_primitives::primitives::ViewingKey::ivk` now returns `SaplingIvk`
- `zcash_primitives::primitives::Note::nf` now returns `Nullifier`.
- `zcash_primitives::transaction`:
  - The `overwintered`, `version`, and `version_group_id` properties of the
    `Transaction` and `TransactionData` structs have been replaced by
    `version: TxVersion`.
  - `components::amount::DEFAULT_FEE` is now 1000 zatoshis, following
    [ZIP 313](https://zips.z.cash/zip-0313).
  - The `nullifier` property of `components::SpendDescription` now has the type
    `Nullifier`.
  - `signature_hash` and `signature_hash_data` now take a `SignableInput`
    argument instead of a `transparent_input` argument.
  - `builder::SaplingOutput::new` and `builder::Builder::add_sapling_output` now
    take `Option<MemoBytes>`.

### Removed
- `zcash_primitives::note_encryption::Memo` (replaced by
  `zcash_primitives::memo::{Memo, MemoBytes}`).

## [0.4.0] - 2020-09-09
### Added
- `zcash_primitives::note_encryption::OutgoingCipherKey` - a symmetric key that
  can be used to recover a single Sapling output. This will eventually be used
  to implement Sapling payment disclosures.

### Changed
- MSRV is now 1.44.1.
- `zcash_primitives::note_encryption`:
  - `SaplingNoteEncryption::new` now takes `Option<OutgoingViewingKey>`. Setting
    this to `None` prevents the note from being recovered from the block chain
    by the sender.
    - The `rng: &mut R` parameter (where `R: RngCore + CryptoRng`) has been
      changed to `rng: R` to enable this use case.
  - `prf_ock` now returns `OutgoingCipherKey`.
  - `try_sapling_output_recovery_with_ock` now takes `&OutgoingCipherKey`.
- `zcash_primitives::transaction::builder`:
  - `SaplingOutput::new` and `Builder::add_sapling_output` now take
    `Option<OutgoingViewingKey>` (exposing the new unrecoverable note option).
- Bumped dependencies to `ff 0.8`, `group 0.8`, `bls12_381 0.3.1`,
  `jubjub 0.5.1`, `secp256k1 0.19`.

## [0.3.0] - 2020-08-24
TBD

## [0.2.0] - 2020-03-13
TBD

## [0.1.0] - 2019-10-08
Initial release.