Move `zcash_note_encryption` component to https://github.com/zcash/zcash_note_encryption
The `zcash_note_encryption` component crate has been factored out to its own repository, to avoid circular crate dependencies involving https://github.com/zcash/librustzcash and the https://github.com/zcash/orchard and https://github.com/zcash/sapling-crypto repositories.
This commit is contained in:
Kris Nuttycombe
parent
236cd569ee
commit
374882b7bc
|
|
@ -1484,7 +1484,7 @@ dependencies = [
|
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"serde",
|
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"subtle",
|
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"tracing",
|
||||
"zcash_note_encryption 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
|
||||
"zcash_note_encryption",
|
||||
]
|
||||
|
||||
[[package]]
|
||||
|
|
@ -2990,7 +2990,7 @@ dependencies = [
|
|||
"which",
|
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"zcash_address",
|
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"zcash_encoding",
|
||||
"zcash_note_encryption 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
|
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"zcash_note_encryption",
|
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"zcash_primitives",
|
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"zcash_proofs",
|
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]
|
||||
|
|
@ -3023,7 +3023,7 @@ dependencies = [
|
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"zcash_address",
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"zcash_client_backend",
|
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"zcash_encoding",
|
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"zcash_note_encryption 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
|
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"zcash_note_encryption",
|
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"zcash_primitives",
|
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"zcash_proofs",
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]
|
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|
|
@ -3060,17 +3060,6 @@ dependencies = [
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"proptest",
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]
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|
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[[package]]
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name = "zcash_note_encryption"
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version = "0.4.0"
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dependencies = [
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"chacha20",
|
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"chacha20poly1305",
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"cipher",
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"rand_core",
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"subtle",
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]
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[[package]]
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name = "zcash_note_encryption"
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version = "0.4.0"
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|
|
@ -3124,7 +3113,7 @@ dependencies = [
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"tracing",
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"zcash_address",
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"zcash_encoding",
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"zcash_note_encryption 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
|
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"zcash_note_encryption",
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]
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[[package]]
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||||
|
|
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|||
|
|
@ -4,7 +4,6 @@ members = [
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"components/f4jumble",
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"components/zcash_address",
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"components/zcash_encoding",
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"components/zcash_note_encryption",
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"zcash_client_backend",
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"zcash_client_sqlite",
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"zcash_extensions",
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|
|
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|
|
@ -1,50 +0,0 @@
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# Changelog
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All notable changes to this library will be documented in this file.
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|
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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).
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||||
|
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## [Unreleased]
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## [0.4.0] - 2023-06-06
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### Changed
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- The `esk` and `ephemeral_key` arguments have been removed from
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`Domain::parse_note_plaintext_without_memo_ovk`. It is therefore no longer
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necessary (or possible) to ensure that `ephemeral_key` is derived from `esk`
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and the diversifier within the note plaintext. We have analyzed the safety of
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this change in the context of callers within `zcash_note_encryption` and
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`orchard`. See https://github.com/zcash/librustzcash/pull/848 and the
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||||
associated issue https://github.com/zcash/librustzcash/issues/802 for
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||||
additional detail.
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|
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## [0.3.0] - 2023-03-22
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### Changed
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||||
- The `recipient` parameter has been removed from `Domain::note_plaintext_bytes`.
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- The `recipient` parameter has been removed from `NoteEncryption::new`. Since
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the `Domain::Note` type is now expected to contain information about the
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recipient of the note, there is no longer any need to pass this information
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in via the encryption context.
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## [0.2.0] - 2022-10-13
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### Added
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- `zcash_note_encryption::Domain`:
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- `Domain::PreparedEphemeralPublicKey` associated type.
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- `Domain::prepare_epk` method, which produces the above type.
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|
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### Changed
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- MSRV is now 1.56.1.
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||||
- `zcash_note_encryption::Domain` now requires `epk` to be converted to
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`Domain::PreparedEphemeralPublicKey` before being passed to
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`Domain::ka_agree_dec`.
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- Changes to batch decryption APIs:
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||||
- The return types of `batch::try_note_decryption` and
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`batch::try_compact_note_decryption` have changed. Now, instead of
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||||
returning entries corresponding to the cartesian product of the IVKs used for
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decryption with the outputs being decrypted, this now returns a vector of
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decryption results of the same length and in the same order as the `outputs`
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||||
argument to the function. Each successful result includes the index of the
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entry in `ivks` used to decrypt the value.
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||||
|
||||
## [0.1.0] - 2021-12-17
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Initial release.
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|
|
@ -1,34 +0,0 @@
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|||
[package]
|
||||
name = "zcash_note_encryption"
|
||||
description = "Note encryption for Zcash transactions"
|
||||
version = "0.4.0"
|
||||
authors = [
|
||||
"Jack Grigg <jack@electriccoin.co>",
|
||||
"Kris Nuttycombe <kris@electriccoin.co>"
|
||||
]
|
||||
homepage = "https://github.com/zcash/librustzcash"
|
||||
repository = "https://github.com/zcash/librustzcash"
|
||||
readme = "README.md"
|
||||
license = "MIT OR Apache-2.0"
|
||||
edition = "2021"
|
||||
rust-version = "1.56.1"
|
||||
categories = ["cryptography::cryptocurrencies"]
|
||||
|
||||
[package.metadata.docs.rs]
|
||||
all-features = true
|
||||
rustdoc-args = ["--cfg", "docsrs"]
|
||||
|
||||
[dependencies]
|
||||
cipher = { version = "0.4", default-features = false }
|
||||
chacha20 = { version = "0.9", default-features = false }
|
||||
chacha20poly1305 = { version = "0.10", default-features = false }
|
||||
rand_core = { version = "0.6", default-features = false }
|
||||
subtle = { version = "2.3", default-features = false }
|
||||
|
||||
[features]
|
||||
default = ["alloc"]
|
||||
alloc = []
|
||||
pre-zip-212 = []
|
||||
|
||||
[lib]
|
||||
bench = false
|
||||
|
|
@ -1,202 +0,0 @@
|
|||
Apache License
|
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Version 2.0, January 2004
|
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http://www.apache.org/licenses/
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@ -1,21 +0,0 @@
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The MIT License (MIT)
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Copyright (c) 2021 Electric Coin Company
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|
@ -1,30 +0,0 @@
|
|||
# zcash_note_encryption
|
||||
|
||||
This crate implements the [in-band secret distribution scheme] for the Sapling and
|
||||
Orchard protocols. It provides reusable methods that implement common note encryption
|
||||
and trial decryption logic, and enforce protocol-agnostic verification requirements.
|
||||
|
||||
Protocol-specific logic is handled via the `Domain` trait. Implementations of this
|
||||
trait are provided in the [`zcash_primitives`] (for Sapling) and [`orchard`] crates;
|
||||
users with their own existing types can similarly implement the trait themselves.
|
||||
|
||||
[in-band secret distribution scheme]: https://zips.z.cash/protocol/protocol.pdf#saplingandorchardinband
|
||||
[`zcash_primitives`]: https://crates.io/crates/zcash_primitives
|
||||
[`orchard`]: https://crates.io/crates/orchard
|
||||
|
||||
## License
|
||||
|
||||
Licensed under either of
|
||||
|
||||
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
|
||||
http://www.apache.org/licenses/LICENSE-2.0)
|
||||
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
|
||||
|
||||
at your option.
|
||||
|
||||
### Contribution
|
||||
|
||||
Unless you explicitly state otherwise, any contribution intentionally
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||||
submitted for inclusion in the work by you, as defined in the Apache-2.0
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||||
license, shall be dual licensed as above, without any additional terms or
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||||
conditions.
|
||||
|
|
@ -1,86 +0,0 @@
|
|||
//! APIs for batch trial decryption.
|
||||
|
||||
use alloc::vec::Vec; // module is alloc only
|
||||
|
||||
use crate::{
|
||||
try_compact_note_decryption_inner, try_note_decryption_inner, BatchDomain, EphemeralKeyBytes,
|
||||
ShieldedOutput, COMPACT_NOTE_SIZE, ENC_CIPHERTEXT_SIZE,
|
||||
};
|
||||
|
||||
/// Trial decryption of a batch of notes with a set of recipients.
|
||||
///
|
||||
/// This is the batched version of [`crate::try_note_decryption`].
|
||||
///
|
||||
/// Returns a vector containing the decrypted result for each output,
|
||||
/// with the same length and in the same order as the outputs were
|
||||
/// provided, along with the index in the `ivks` slice associated with
|
||||
/// the IVK that successfully decrypted the output.
|
||||
#[allow(clippy::type_complexity)]
|
||||
pub fn try_note_decryption<D: BatchDomain, Output: ShieldedOutput<D, ENC_CIPHERTEXT_SIZE>>(
|
||||
ivks: &[D::IncomingViewingKey],
|
||||
outputs: &[(D, Output)],
|
||||
) -> Vec<Option<((D::Note, D::Recipient, D::Memo), usize)>> {
|
||||
batch_note_decryption(ivks, outputs, try_note_decryption_inner)
|
||||
}
|
||||
|
||||
/// Trial decryption of a batch of notes for light clients with a set of recipients.
|
||||
///
|
||||
/// This is the batched version of [`crate::try_compact_note_decryption`].
|
||||
///
|
||||
/// Returns a vector containing the decrypted result for each output,
|
||||
/// with the same length and in the same order as the outputs were
|
||||
/// provided, along with the index in the `ivks` slice associated with
|
||||
/// the IVK that successfully decrypted the output.
|
||||
#[allow(clippy::type_complexity)]
|
||||
pub fn try_compact_note_decryption<D: BatchDomain, Output: ShieldedOutput<D, COMPACT_NOTE_SIZE>>(
|
||||
ivks: &[D::IncomingViewingKey],
|
||||
outputs: &[(D, Output)],
|
||||
) -> Vec<Option<((D::Note, D::Recipient), usize)>> {
|
||||
batch_note_decryption(ivks, outputs, try_compact_note_decryption_inner)
|
||||
}
|
||||
|
||||
fn batch_note_decryption<D: BatchDomain, Output: ShieldedOutput<D, CS>, F, FR, const CS: usize>(
|
||||
ivks: &[D::IncomingViewingKey],
|
||||
outputs: &[(D, Output)],
|
||||
decrypt_inner: F,
|
||||
) -> Vec<Option<(FR, usize)>>
|
||||
where
|
||||
F: Fn(&D, &D::IncomingViewingKey, &EphemeralKeyBytes, &Output, &D::SymmetricKey) -> Option<FR>,
|
||||
{
|
||||
if ivks.is_empty() {
|
||||
return (0..outputs.len()).map(|_| None).collect();
|
||||
};
|
||||
|
||||
// Fetch the ephemeral keys for each output, and batch-parse and prepare them.
|
||||
let ephemeral_keys = D::batch_epk(outputs.iter().map(|(_, output)| output.ephemeral_key()));
|
||||
|
||||
// Derive the shared secrets for all combinations of (ivk, output).
|
||||
// The scalar multiplications cannot benefit from batching.
|
||||
let items = ephemeral_keys.iter().flat_map(|(epk, ephemeral_key)| {
|
||||
ivks.iter().map(move |ivk| {
|
||||
(
|
||||
epk.as_ref().map(|epk| D::ka_agree_dec(ivk, epk)),
|
||||
ephemeral_key,
|
||||
)
|
||||
})
|
||||
});
|
||||
|
||||
// Run the batch-KDF to obtain the symmetric keys from the shared secrets.
|
||||
let keys = D::batch_kdf(items);
|
||||
|
||||
// Finish the trial decryption!
|
||||
keys.chunks(ivks.len())
|
||||
.zip(ephemeral_keys.iter().zip(outputs.iter()))
|
||||
.map(|(key_chunk, ((_, ephemeral_key), (domain, output)))| {
|
||||
key_chunk
|
||||
.iter()
|
||||
.zip(ivks.iter().enumerate())
|
||||
.filter_map(|(key, (i, ivk))| {
|
||||
key.as_ref()
|
||||
.and_then(|key| decrypt_inner(domain, ivk, ephemeral_key, output, key))
|
||||
.map(|out| (out, i))
|
||||
})
|
||||
.next()
|
||||
})
|
||||
.collect::<Vec<Option<_>>>()
|
||||
}
|
||||
|
|
@ -1,696 +0,0 @@
|
|||
//! Note encryption for Zcash transactions.
|
||||
//!
|
||||
//! This crate implements the [in-band secret distribution scheme] for the Sapling and
|
||||
//! Orchard protocols. It provides reusable methods that implement common note encryption
|
||||
//! and trial decryption logic, and enforce protocol-agnostic verification requirements.
|
||||
//!
|
||||
//! Protocol-specific logic is handled via the [`Domain`] trait. Implementations of this
|
||||
//! trait are provided in the [`zcash_primitives`] (for Sapling) and [`orchard`] crates;
|
||||
//! users with their own existing types can similarly implement the trait themselves.
|
||||
//!
|
||||
//! [in-band secret distribution scheme]: https://zips.z.cash/protocol/protocol.pdf#saplingandorchardinband
|
||||
//! [`zcash_primitives`]: https://crates.io/crates/zcash_primitives
|
||||
//! [`orchard`]: https://crates.io/crates/orchard
|
||||
|
||||
#![no_std]
|
||||
#![cfg_attr(docsrs, feature(doc_cfg))]
|
||||
// Catch documentation errors caused by code changes.
|
||||
#![deny(rustdoc::broken_intra_doc_links)]
|
||||
#![deny(unsafe_code)]
|
||||
// TODO: #![deny(missing_docs)]
|
||||
|
||||
use core::fmt::{self, Write};
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
extern crate alloc;
|
||||
#[cfg(feature = "alloc")]
|
||||
use alloc::vec::Vec;
|
||||
|
||||
use chacha20::{
|
||||
cipher::{StreamCipher, StreamCipherSeek},
|
||||
ChaCha20,
|
||||
};
|
||||
use chacha20poly1305::{aead::AeadInPlace, ChaCha20Poly1305, KeyInit};
|
||||
use cipher::KeyIvInit;
|
||||
|
||||
use rand_core::RngCore;
|
||||
use subtle::{Choice, ConstantTimeEq};
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
|
||||
pub mod batch;
|
||||
|
||||
/// The size of a compact note.
|
||||
pub const COMPACT_NOTE_SIZE: usize = 1 + // version
|
||||
11 + // diversifier
|
||||
8 + // value
|
||||
32; // rseed (or rcm prior to ZIP 212)
|
||||
/// The size of [`NotePlaintextBytes`].
|
||||
pub const NOTE_PLAINTEXT_SIZE: usize = COMPACT_NOTE_SIZE + 512;
|
||||
/// The size of [`OutPlaintextBytes`].
|
||||
pub const OUT_PLAINTEXT_SIZE: usize = 32 + // pk_d
|
||||
32; // esk
|
||||
const AEAD_TAG_SIZE: usize = 16;
|
||||
/// The size of an encrypted note plaintext.
|
||||
pub const ENC_CIPHERTEXT_SIZE: usize = NOTE_PLAINTEXT_SIZE + AEAD_TAG_SIZE;
|
||||
/// The size of an encrypted outgoing plaintext.
|
||||
pub const OUT_CIPHERTEXT_SIZE: usize = OUT_PLAINTEXT_SIZE + AEAD_TAG_SIZE;
|
||||
|
||||
/// A symmetric key that can be used to recover a single Sapling or Orchard output.
|
||||
pub struct OutgoingCipherKey(pub [u8; 32]);
|
||||
|
||||
impl From<[u8; 32]> for OutgoingCipherKey {
|
||||
fn from(ock: [u8; 32]) -> Self {
|
||||
OutgoingCipherKey(ock)
|
||||
}
|
||||
}
|
||||
|
||||
impl AsRef<[u8]> for OutgoingCipherKey {
|
||||
fn as_ref(&self) -> &[u8] {
|
||||
&self.0
|
||||
}
|
||||
}
|
||||
|
||||
/// Newtype representing the byte encoding of an [`EphemeralPublicKey`].
|
||||
///
|
||||
/// [`EphemeralPublicKey`]: Domain::EphemeralPublicKey
|
||||
#[derive(Clone)]
|
||||
pub struct EphemeralKeyBytes(pub [u8; 32]);
|
||||
|
||||
impl fmt::Debug for EphemeralKeyBytes {
|
||||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||||
struct HexFmt<'b>(&'b [u8]);
|
||||
impl<'b> fmt::Debug for HexFmt<'b> {
|
||||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||||
f.write_char('"')?;
|
||||
for b in self.0 {
|
||||
f.write_fmt(format_args!("{:02x}", b))?;
|
||||
}
|
||||
f.write_char('"')
|
||||
}
|
||||
}
|
||||
|
||||
f.debug_tuple("EphemeralKeyBytes")
|
||||
.field(&HexFmt(&self.0))
|
||||
.finish()
|
||||
}
|
||||
}
|
||||
|
||||
impl AsRef<[u8]> for EphemeralKeyBytes {
|
||||
fn as_ref(&self) -> &[u8] {
|
||||
&self.0
|
||||
}
|
||||
}
|
||||
|
||||
impl From<[u8; 32]> for EphemeralKeyBytes {
|
||||
fn from(value: [u8; 32]) -> EphemeralKeyBytes {
|
||||
EphemeralKeyBytes(value)
|
||||
}
|
||||
}
|
||||
|
||||
impl ConstantTimeEq for EphemeralKeyBytes {
|
||||
fn ct_eq(&self, other: &Self) -> Choice {
|
||||
self.0.ct_eq(&other.0)
|
||||
}
|
||||
}
|
||||
|
||||
/// Newtype representing the byte encoding of a note plaintext.
|
||||
pub struct NotePlaintextBytes(pub [u8; NOTE_PLAINTEXT_SIZE]);
|
||||
/// Newtype representing the byte encoding of a outgoing plaintext.
|
||||
pub struct OutPlaintextBytes(pub [u8; OUT_PLAINTEXT_SIZE]);
|
||||
|
||||
#[derive(Copy, Clone, PartialEq, Eq)]
|
||||
enum NoteValidity {
|
||||
Valid,
|
||||
Invalid,
|
||||
}
|
||||
|
||||
/// Trait that encapsulates protocol-specific note encryption types and logic.
|
||||
///
|
||||
/// This trait enables most of the note encryption logic to be shared between Sapling and
|
||||
/// Orchard, as well as between different implementations of those protocols.
|
||||
pub trait Domain {
|
||||
type EphemeralSecretKey: ConstantTimeEq;
|
||||
type EphemeralPublicKey;
|
||||
type PreparedEphemeralPublicKey;
|
||||
type SharedSecret;
|
||||
type SymmetricKey: AsRef<[u8]>;
|
||||
type Note;
|
||||
type Recipient;
|
||||
type DiversifiedTransmissionKey;
|
||||
type IncomingViewingKey;
|
||||
type OutgoingViewingKey;
|
||||
type ValueCommitment;
|
||||
type ExtractedCommitment;
|
||||
type ExtractedCommitmentBytes: Eq + for<'a> From<&'a Self::ExtractedCommitment>;
|
||||
type Memo;
|
||||
|
||||
/// Derives the `EphemeralSecretKey` corresponding to this note.
|
||||
///
|
||||
/// Returns `None` if the note was created prior to [ZIP 212], and doesn't have a
|
||||
/// deterministic `EphemeralSecretKey`.
|
||||
///
|
||||
/// [ZIP 212]: https://zips.z.cash/zip-0212
|
||||
fn derive_esk(note: &Self::Note) -> Option<Self::EphemeralSecretKey>;
|
||||
|
||||
/// Extracts the `DiversifiedTransmissionKey` from the note.
|
||||
fn get_pk_d(note: &Self::Note) -> Self::DiversifiedTransmissionKey;
|
||||
|
||||
/// Prepare an ephemeral public key for more efficient scalar multiplication.
|
||||
fn prepare_epk(epk: Self::EphemeralPublicKey) -> Self::PreparedEphemeralPublicKey;
|
||||
|
||||
/// Derives `EphemeralPublicKey` from `esk` and the note's diversifier.
|
||||
fn ka_derive_public(
|
||||
note: &Self::Note,
|
||||
esk: &Self::EphemeralSecretKey,
|
||||
) -> Self::EphemeralPublicKey;
|
||||
|
||||
/// Derives the `SharedSecret` from the sender's information during note encryption.
|
||||
fn ka_agree_enc(
|
||||
esk: &Self::EphemeralSecretKey,
|
||||
pk_d: &Self::DiversifiedTransmissionKey,
|
||||
) -> Self::SharedSecret;
|
||||
|
||||
/// Derives the `SharedSecret` from the recipient's information during note trial
|
||||
/// decryption.
|
||||
fn ka_agree_dec(
|
||||
ivk: &Self::IncomingViewingKey,
|
||||
epk: &Self::PreparedEphemeralPublicKey,
|
||||
) -> Self::SharedSecret;
|
||||
|
||||
/// Derives the `SymmetricKey` used to encrypt the note plaintext.
|
||||
///
|
||||
/// `secret` is the `SharedSecret` obtained from [`Self::ka_agree_enc`] or
|
||||
/// [`Self::ka_agree_dec`].
|
||||
///
|
||||
/// `ephemeral_key` is the byte encoding of the [`EphemeralPublicKey`] used to derive
|
||||
/// `secret`. During encryption it is derived via [`Self::epk_bytes`]; during trial
|
||||
/// decryption it is obtained from [`ShieldedOutput::ephemeral_key`].
|
||||
///
|
||||
/// [`EphemeralPublicKey`]: Self::EphemeralPublicKey
|
||||
/// [`EphemeralSecretKey`]: Self::EphemeralSecretKey
|
||||
fn kdf(secret: Self::SharedSecret, ephemeral_key: &EphemeralKeyBytes) -> Self::SymmetricKey;
|
||||
|
||||
/// Encodes the given `Note` and `Memo` as a note plaintext.
|
||||
fn note_plaintext_bytes(note: &Self::Note, memo: &Self::Memo) -> NotePlaintextBytes;
|
||||
|
||||
/// Derives the [`OutgoingCipherKey`] for an encrypted note, given the note-specific
|
||||
/// public data and an `OutgoingViewingKey`.
|
||||
fn derive_ock(
|
||||
ovk: &Self::OutgoingViewingKey,
|
||||
cv: &Self::ValueCommitment,
|
||||
cmstar_bytes: &Self::ExtractedCommitmentBytes,
|
||||
ephemeral_key: &EphemeralKeyBytes,
|
||||
) -> OutgoingCipherKey;
|
||||
|
||||
/// Encodes the outgoing plaintext for the given note.
|
||||
fn outgoing_plaintext_bytes(
|
||||
note: &Self::Note,
|
||||
esk: &Self::EphemeralSecretKey,
|
||||
) -> OutPlaintextBytes;
|
||||
|
||||
/// Returns the byte encoding of the given `EphemeralPublicKey`.
|
||||
fn epk_bytes(epk: &Self::EphemeralPublicKey) -> EphemeralKeyBytes;
|
||||
|
||||
/// Attempts to parse `ephemeral_key` as an `EphemeralPublicKey`.
|
||||
///
|
||||
/// Returns `None` if `ephemeral_key` is not a valid byte encoding of an
|
||||
/// `EphemeralPublicKey`.
|
||||
fn epk(ephemeral_key: &EphemeralKeyBytes) -> Option<Self::EphemeralPublicKey>;
|
||||
|
||||
/// Derives the `ExtractedCommitment` for this note.
|
||||
fn cmstar(note: &Self::Note) -> Self::ExtractedCommitment;
|
||||
|
||||
/// Parses the given note plaintext from the recipient's perspective.
|
||||
///
|
||||
/// The implementation of this method must check that:
|
||||
/// - The note plaintext version is valid (for the given decryption domain's context,
|
||||
/// which may be passed via `self`).
|
||||
/// - The note plaintext contains valid encodings of its various fields.
|
||||
/// - Any domain-specific requirements are satisfied.
|
||||
///
|
||||
/// `&self` is passed here to enable the implementation to enforce contextual checks,
|
||||
/// such as rules like [ZIP 212] that become active at a specific block height.
|
||||
///
|
||||
/// [ZIP 212]: https://zips.z.cash/zip-0212
|
||||
///
|
||||
/// # Panics
|
||||
///
|
||||
/// Panics if `plaintext` is shorter than [`COMPACT_NOTE_SIZE`].
|
||||
fn parse_note_plaintext_without_memo_ivk(
|
||||
&self,
|
||||
ivk: &Self::IncomingViewingKey,
|
||||
plaintext: &[u8],
|
||||
) -> Option<(Self::Note, Self::Recipient)>;
|
||||
|
||||
/// Parses the given note plaintext from the sender's perspective.
|
||||
///
|
||||
/// The implementation of this method must check that:
|
||||
/// - The note plaintext version is valid (for the given decryption domain's context,
|
||||
/// which may be passed via `self`).
|
||||
/// - The note plaintext contains valid encodings of its various fields.
|
||||
/// - Any domain-specific requirements are satisfied.
|
||||
///
|
||||
/// `&self` is passed here to enable the implementation to enforce contextual checks,
|
||||
/// such as rules like [ZIP 212] that become active at a specific block height.
|
||||
///
|
||||
/// [ZIP 212]: https://zips.z.cash/zip-0212
|
||||
fn parse_note_plaintext_without_memo_ovk(
|
||||
&self,
|
||||
pk_d: &Self::DiversifiedTransmissionKey,
|
||||
plaintext: &NotePlaintextBytes,
|
||||
) -> Option<(Self::Note, Self::Recipient)>;
|
||||
|
||||
/// Extracts the memo field from the given note plaintext.
|
||||
///
|
||||
/// # Compatibility
|
||||
///
|
||||
/// `&self` is passed here in anticipation of future changes to memo handling, where
|
||||
/// the memos may no longer be part of the note plaintext.
|
||||
fn extract_memo(&self, plaintext: &NotePlaintextBytes) -> Self::Memo;
|
||||
|
||||
/// Parses the `DiversifiedTransmissionKey` field of the outgoing plaintext.
|
||||
///
|
||||
/// Returns `None` if `out_plaintext` does not contain a valid byte encoding of a
|
||||
/// `DiversifiedTransmissionKey`.
|
||||
fn extract_pk_d(out_plaintext: &OutPlaintextBytes) -> Option<Self::DiversifiedTransmissionKey>;
|
||||
|
||||
/// Parses the `EphemeralSecretKey` field of the outgoing plaintext.
|
||||
///
|
||||
/// Returns `None` if `out_plaintext` does not contain a valid byte encoding of an
|
||||
/// `EphemeralSecretKey`.
|
||||
fn extract_esk(out_plaintext: &OutPlaintextBytes) -> Option<Self::EphemeralSecretKey>;
|
||||
}
|
||||
|
||||
/// Trait that encapsulates protocol-specific batch trial decryption logic.
|
||||
///
|
||||
/// Each batchable operation has a default implementation that calls through to the
|
||||
/// non-batched implementation. Domains can override whichever operations benefit from
|
||||
/// batched logic.
|
||||
#[cfg(feature = "alloc")]
|
||||
#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
|
||||
pub trait BatchDomain: Domain {
|
||||
/// Computes `Self::kdf` on a batch of items.
|
||||
///
|
||||
/// For each item in the batch, if the shared secret is `None`, this returns `None` at
|
||||
/// that position.
|
||||
fn batch_kdf<'a>(
|
||||
items: impl Iterator<Item = (Option<Self::SharedSecret>, &'a EphemeralKeyBytes)>,
|
||||
) -> Vec<Option<Self::SymmetricKey>> {
|
||||
// Default implementation: do the non-batched thing.
|
||||
items
|
||||
.map(|(secret, ephemeral_key)| secret.map(|secret| Self::kdf(secret, ephemeral_key)))
|
||||
.collect()
|
||||
}
|
||||
|
||||
/// Computes `Self::epk` on a batch of ephemeral keys.
|
||||
///
|
||||
/// This is useful for protocols where the underlying curve requires an inversion to
|
||||
/// parse an encoded point.
|
||||
///
|
||||
/// For usability, this returns tuples of the ephemeral keys and the result of parsing
|
||||
/// them.
|
||||
fn batch_epk(
|
||||
ephemeral_keys: impl Iterator<Item = EphemeralKeyBytes>,
|
||||
) -> Vec<(Option<Self::PreparedEphemeralPublicKey>, EphemeralKeyBytes)> {
|
||||
// Default implementation: do the non-batched thing.
|
||||
ephemeral_keys
|
||||
.map(|ephemeral_key| {
|
||||
(
|
||||
Self::epk(&ephemeral_key).map(Self::prepare_epk),
|
||||
ephemeral_key,
|
||||
)
|
||||
})
|
||||
.collect()
|
||||
}
|
||||
}
|
||||
|
||||
/// Trait that provides access to the components of an encrypted transaction output.
|
||||
///
|
||||
/// Implementations of this trait are required to define the length of their ciphertext
|
||||
/// field. In order to use the trial decryption APIs in this crate, the length must be
|
||||
/// either [`ENC_CIPHERTEXT_SIZE`] or [`COMPACT_NOTE_SIZE`].
|
||||
pub trait ShieldedOutput<D: Domain, const CIPHERTEXT_SIZE: usize> {
|
||||
/// Exposes the `ephemeral_key` field of the output.
|
||||
fn ephemeral_key(&self) -> EphemeralKeyBytes;
|
||||
|
||||
/// Exposes the `cmu_bytes` or `cmx_bytes` field of the output.
|
||||
fn cmstar_bytes(&self) -> D::ExtractedCommitmentBytes;
|
||||
|
||||
/// Exposes the note ciphertext of the output.
|
||||
fn enc_ciphertext(&self) -> &[u8; CIPHERTEXT_SIZE];
|
||||
}
|
||||
|
||||
/// A struct containing context required for encrypting Sapling and Orchard notes.
|
||||
///
|
||||
/// This struct provides a safe API for encrypting Sapling and Orchard notes. In particular, it
|
||||
/// enforces that fresh ephemeral keys are used for every note, and that the ciphertexts are
|
||||
/// consistent with each other.
|
||||
///
|
||||
/// Implements section 4.19 of the
|
||||
/// [Zcash Protocol Specification](https://zips.z.cash/protocol/nu5.pdf#saplingandorchardinband)
|
||||
pub struct NoteEncryption<D: Domain> {
|
||||
epk: D::EphemeralPublicKey,
|
||||
esk: D::EphemeralSecretKey,
|
||||
note: D::Note,
|
||||
memo: D::Memo,
|
||||
/// `None` represents the `ovk = ⊥` case.
|
||||
ovk: Option<D::OutgoingViewingKey>,
|
||||
}
|
||||
|
||||
impl<D: Domain> NoteEncryption<D> {
|
||||
/// Construct a new note encryption context for the specified note,
|
||||
/// recipient, and memo.
|
||||
pub fn new(ovk: Option<D::OutgoingViewingKey>, note: D::Note, memo: D::Memo) -> Self {
|
||||
let esk = D::derive_esk(¬e).expect("ZIP 212 is active.");
|
||||
NoteEncryption {
|
||||
epk: D::ka_derive_public(¬e, &esk),
|
||||
esk,
|
||||
note,
|
||||
memo,
|
||||
ovk,
|
||||
}
|
||||
}
|
||||
|
||||
/// For use only with Sapling. This method is preserved in order that test code
|
||||
/// be able to generate pre-ZIP-212 ciphertexts so that tests can continue to
|
||||
/// cover pre-ZIP-212 transaction decryption.
|
||||
#[cfg(feature = "pre-zip-212")]
|
||||
#[cfg_attr(docsrs, doc(cfg(feature = "pre-zip-212")))]
|
||||
pub fn new_with_esk(
|
||||
esk: D::EphemeralSecretKey,
|
||||
ovk: Option<D::OutgoingViewingKey>,
|
||||
note: D::Note,
|
||||
memo: D::Memo,
|
||||
) -> Self {
|
||||
NoteEncryption {
|
||||
epk: D::ka_derive_public(¬e, &esk),
|
||||
esk,
|
||||
note,
|
||||
memo,
|
||||
ovk,
|
||||
}
|
||||
}
|
||||
|
||||
/// Exposes the ephemeral secret key being used to encrypt this note.
|
||||
pub fn esk(&self) -> &D::EphemeralSecretKey {
|
||||
&self.esk
|
||||
}
|
||||
|
||||
/// Exposes the encoding of the ephemeral public key being used to encrypt this note.
|
||||
pub fn epk(&self) -> &D::EphemeralPublicKey {
|
||||
&self.epk
|
||||
}
|
||||
|
||||
/// Generates `encCiphertext` for this note.
|
||||
pub fn encrypt_note_plaintext(&self) -> [u8; ENC_CIPHERTEXT_SIZE] {
|
||||
let pk_d = D::get_pk_d(&self.note);
|
||||
let shared_secret = D::ka_agree_enc(&self.esk, &pk_d);
|
||||
let key = D::kdf(shared_secret, &D::epk_bytes(&self.epk));
|
||||
let input = D::note_plaintext_bytes(&self.note, &self.memo);
|
||||
|
||||
let mut output = [0u8; ENC_CIPHERTEXT_SIZE];
|
||||
output[..NOTE_PLAINTEXT_SIZE].copy_from_slice(&input.0);
|
||||
let tag = ChaCha20Poly1305::new(key.as_ref().into())
|
||||
.encrypt_in_place_detached(
|
||||
[0u8; 12][..].into(),
|
||||
&[],
|
||||
&mut output[..NOTE_PLAINTEXT_SIZE],
|
||||
)
|
||||
.unwrap();
|
||||
output[NOTE_PLAINTEXT_SIZE..].copy_from_slice(&tag);
|
||||
|
||||
output
|
||||
}
|
||||
|
||||
/// Generates `outCiphertext` for this note.
|
||||
pub fn encrypt_outgoing_plaintext<R: RngCore>(
|
||||
&self,
|
||||
cv: &D::ValueCommitment,
|
||||
cmstar: &D::ExtractedCommitment,
|
||||
rng: &mut R,
|
||||
) -> [u8; OUT_CIPHERTEXT_SIZE] {
|
||||
let (ock, input) = if let Some(ovk) = &self.ovk {
|
||||
let ock = D::derive_ock(ovk, cv, &cmstar.into(), &D::epk_bytes(&self.epk));
|
||||
let input = D::outgoing_plaintext_bytes(&self.note, &self.esk);
|
||||
|
||||
(ock, input)
|
||||
} else {
|
||||
// ovk = ⊥
|
||||
let mut ock = OutgoingCipherKey([0; 32]);
|
||||
let mut input = [0u8; OUT_PLAINTEXT_SIZE];
|
||||
|
||||
rng.fill_bytes(&mut ock.0);
|
||||
rng.fill_bytes(&mut input);
|
||||
|
||||
(ock, OutPlaintextBytes(input))
|
||||
};
|
||||
|
||||
let mut output = [0u8; OUT_CIPHERTEXT_SIZE];
|
||||
output[..OUT_PLAINTEXT_SIZE].copy_from_slice(&input.0);
|
||||
let tag = ChaCha20Poly1305::new(ock.as_ref().into())
|
||||
.encrypt_in_place_detached([0u8; 12][..].into(), &[], &mut output[..OUT_PLAINTEXT_SIZE])
|
||||
.unwrap();
|
||||
output[OUT_PLAINTEXT_SIZE..].copy_from_slice(&tag);
|
||||
|
||||
output
|
||||
}
|
||||
}
|
||||
|
||||
/// Trial decryption of the full note plaintext by the recipient.
|
||||
///
|
||||
/// Attempts to decrypt and validate the given shielded output using the given `ivk`.
|
||||
/// If successful, the corresponding note and memo are returned, along with the address to
|
||||
/// which the note was sent.
|
||||
///
|
||||
/// Implements section 4.19.2 of the
|
||||
/// [Zcash Protocol Specification](https://zips.z.cash/protocol/nu5.pdf#decryptivk).
|
||||
pub fn try_note_decryption<D: Domain, Output: ShieldedOutput<D, ENC_CIPHERTEXT_SIZE>>(
|
||||
domain: &D,
|
||||
ivk: &D::IncomingViewingKey,
|
||||
output: &Output,
|
||||
) -> Option<(D::Note, D::Recipient, D::Memo)> {
|
||||
let ephemeral_key = output.ephemeral_key();
|
||||
|
||||
let epk = D::prepare_epk(D::epk(&ephemeral_key)?);
|
||||
let shared_secret = D::ka_agree_dec(ivk, &epk);
|
||||
let key = D::kdf(shared_secret, &ephemeral_key);
|
||||
|
||||
try_note_decryption_inner(domain, ivk, &ephemeral_key, output, &key)
|
||||
}
|
||||
|
||||
fn try_note_decryption_inner<D: Domain, Output: ShieldedOutput<D, ENC_CIPHERTEXT_SIZE>>(
|
||||
domain: &D,
|
||||
ivk: &D::IncomingViewingKey,
|
||||
ephemeral_key: &EphemeralKeyBytes,
|
||||
output: &Output,
|
||||
key: &D::SymmetricKey,
|
||||
) -> Option<(D::Note, D::Recipient, D::Memo)> {
|
||||
let enc_ciphertext = output.enc_ciphertext();
|
||||
|
||||
let mut plaintext =
|
||||
NotePlaintextBytes(enc_ciphertext[..NOTE_PLAINTEXT_SIZE].try_into().unwrap());
|
||||
|
||||
ChaCha20Poly1305::new(key.as_ref().into())
|
||||
.decrypt_in_place_detached(
|
||||
[0u8; 12][..].into(),
|
||||
&[],
|
||||
&mut plaintext.0,
|
||||
enc_ciphertext[NOTE_PLAINTEXT_SIZE..].into(),
|
||||
)
|
||||
.ok()?;
|
||||
|
||||
let (note, to) = parse_note_plaintext_without_memo_ivk(
|
||||
domain,
|
||||
ivk,
|
||||
ephemeral_key,
|
||||
&output.cmstar_bytes(),
|
||||
&plaintext.0,
|
||||
)?;
|
||||
let memo = domain.extract_memo(&plaintext);
|
||||
|
||||
Some((note, to, memo))
|
||||
}
|
||||
|
||||
fn parse_note_plaintext_without_memo_ivk<D: Domain>(
|
||||
domain: &D,
|
||||
ivk: &D::IncomingViewingKey,
|
||||
ephemeral_key: &EphemeralKeyBytes,
|
||||
cmstar_bytes: &D::ExtractedCommitmentBytes,
|
||||
plaintext: &[u8],
|
||||
) -> Option<(D::Note, D::Recipient)> {
|
||||
let (note, to) = domain.parse_note_plaintext_without_memo_ivk(ivk, plaintext)?;
|
||||
|
||||
if let NoteValidity::Valid = check_note_validity::<D>(¬e, ephemeral_key, cmstar_bytes) {
|
||||
Some((note, to))
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
|
||||
fn check_note_validity<D: Domain>(
|
||||
note: &D::Note,
|
||||
ephemeral_key: &EphemeralKeyBytes,
|
||||
cmstar_bytes: &D::ExtractedCommitmentBytes,
|
||||
) -> NoteValidity {
|
||||
if &D::ExtractedCommitmentBytes::from(&D::cmstar(note)) == cmstar_bytes {
|
||||
// In the case corresponding to specification section 4.19.3, we check that `esk` is equal
|
||||
// to `D::derive_esk(note)` prior to calling this method.
|
||||
if let Some(derived_esk) = D::derive_esk(note) {
|
||||
if D::epk_bytes(&D::ka_derive_public(note, &derived_esk))
|
||||
.ct_eq(ephemeral_key)
|
||||
.into()
|
||||
{
|
||||
NoteValidity::Valid
|
||||
} else {
|
||||
NoteValidity::Invalid
|
||||
}
|
||||
} else {
|
||||
// Before ZIP 212
|
||||
NoteValidity::Valid
|
||||
}
|
||||
} else {
|
||||
// Published commitment doesn't match calculated commitment
|
||||
NoteValidity::Invalid
|
||||
}
|
||||
}
|
||||
|
||||
/// Trial decryption of the compact note plaintext by the recipient for light clients.
|
||||
///
|
||||
/// Attempts to decrypt and validate the given compact shielded output using the
|
||||
/// given `ivk`. If successful, the corresponding note is returned, along with the address
|
||||
/// to which the note was sent.
|
||||
///
|
||||
/// Implements the procedure specified in [`ZIP 307`].
|
||||
///
|
||||
/// [`ZIP 307`]: https://zips.z.cash/zip-0307
|
||||
pub fn try_compact_note_decryption<D: Domain, Output: ShieldedOutput<D, COMPACT_NOTE_SIZE>>(
|
||||
domain: &D,
|
||||
ivk: &D::IncomingViewingKey,
|
||||
output: &Output,
|
||||
) -> Option<(D::Note, D::Recipient)> {
|
||||
let ephemeral_key = output.ephemeral_key();
|
||||
|
||||
let epk = D::prepare_epk(D::epk(&ephemeral_key)?);
|
||||
let shared_secret = D::ka_agree_dec(ivk, &epk);
|
||||
let key = D::kdf(shared_secret, &ephemeral_key);
|
||||
|
||||
try_compact_note_decryption_inner(domain, ivk, &ephemeral_key, output, &key)
|
||||
}
|
||||
|
||||
fn try_compact_note_decryption_inner<D: Domain, Output: ShieldedOutput<D, COMPACT_NOTE_SIZE>>(
|
||||
domain: &D,
|
||||
ivk: &D::IncomingViewingKey,
|
||||
ephemeral_key: &EphemeralKeyBytes,
|
||||
output: &Output,
|
||||
key: &D::SymmetricKey,
|
||||
) -> Option<(D::Note, D::Recipient)> {
|
||||
// Start from block 1 to skip over Poly1305 keying output
|
||||
let mut plaintext = [0; COMPACT_NOTE_SIZE];
|
||||
plaintext.copy_from_slice(output.enc_ciphertext());
|
||||
let mut keystream = ChaCha20::new(key.as_ref().into(), [0u8; 12][..].into());
|
||||
keystream.seek(64);
|
||||
keystream.apply_keystream(&mut plaintext);
|
||||
|
||||
parse_note_plaintext_without_memo_ivk(
|
||||
domain,
|
||||
ivk,
|
||||
ephemeral_key,
|
||||
&output.cmstar_bytes(),
|
||||
&plaintext,
|
||||
)
|
||||
}
|
||||
|
||||
/// Recovery of the full note plaintext by the sender.
|
||||
///
|
||||
/// Attempts to decrypt and validate the given shielded output using the given `ovk`.
|
||||
/// If successful, the corresponding note and memo are returned, along with the address to
|
||||
/// which the note was sent.
|
||||
///
|
||||
/// Implements [Zcash Protocol Specification section 4.19.3][decryptovk].
|
||||
///
|
||||
/// [decryptovk]: https://zips.z.cash/protocol/nu5.pdf#decryptovk
|
||||
pub fn try_output_recovery_with_ovk<D: Domain, Output: ShieldedOutput<D, ENC_CIPHERTEXT_SIZE>>(
|
||||
domain: &D,
|
||||
ovk: &D::OutgoingViewingKey,
|
||||
output: &Output,
|
||||
cv: &D::ValueCommitment,
|
||||
out_ciphertext: &[u8; OUT_CIPHERTEXT_SIZE],
|
||||
) -> Option<(D::Note, D::Recipient, D::Memo)> {
|
||||
let ock = D::derive_ock(ovk, cv, &output.cmstar_bytes(), &output.ephemeral_key());
|
||||
try_output_recovery_with_ock(domain, &ock, output, out_ciphertext)
|
||||
}
|
||||
|
||||
/// Recovery of the full note plaintext by the sender.
|
||||
///
|
||||
/// Attempts to decrypt and validate the given shielded output using the given `ock`.
|
||||
/// If successful, the corresponding note and memo are returned, along with the address to
|
||||
/// which the note was sent.
|
||||
///
|
||||
/// Implements part of section 4.19.3 of the
|
||||
/// [Zcash Protocol Specification](https://zips.z.cash/protocol/nu5.pdf#decryptovk).
|
||||
/// For decryption using a Full Viewing Key see [`try_output_recovery_with_ovk`].
|
||||
pub fn try_output_recovery_with_ock<D: Domain, Output: ShieldedOutput<D, ENC_CIPHERTEXT_SIZE>>(
|
||||
domain: &D,
|
||||
ock: &OutgoingCipherKey,
|
||||
output: &Output,
|
||||
out_ciphertext: &[u8; OUT_CIPHERTEXT_SIZE],
|
||||
) -> Option<(D::Note, D::Recipient, D::Memo)> {
|
||||
let enc_ciphertext = output.enc_ciphertext();
|
||||
|
||||
let mut op = OutPlaintextBytes([0; OUT_PLAINTEXT_SIZE]);
|
||||
op.0.copy_from_slice(&out_ciphertext[..OUT_PLAINTEXT_SIZE]);
|
||||
|
||||
ChaCha20Poly1305::new(ock.as_ref().into())
|
||||
.decrypt_in_place_detached(
|
||||
[0u8; 12][..].into(),
|
||||
&[],
|
||||
&mut op.0,
|
||||
out_ciphertext[OUT_PLAINTEXT_SIZE..].into(),
|
||||
)
|
||||
.ok()?;
|
||||
|
||||
let pk_d = D::extract_pk_d(&op)?;
|
||||
let esk = D::extract_esk(&op)?;
|
||||
|
||||
let ephemeral_key = output.ephemeral_key();
|
||||
let shared_secret = D::ka_agree_enc(&esk, &pk_d);
|
||||
// The small-order point check at the point of output parsing rejects
|
||||
// non-canonical encodings, so reencoding here for the KDF should
|
||||
// be okay.
|
||||
let key = D::kdf(shared_secret, &ephemeral_key);
|
||||
|
||||
let mut plaintext = NotePlaintextBytes([0; NOTE_PLAINTEXT_SIZE]);
|
||||
plaintext
|
||||
.0
|
||||
.copy_from_slice(&enc_ciphertext[..NOTE_PLAINTEXT_SIZE]);
|
||||
|
||||
ChaCha20Poly1305::new(key.as_ref().into())
|
||||
.decrypt_in_place_detached(
|
||||
[0u8; 12][..].into(),
|
||||
&[],
|
||||
&mut plaintext.0,
|
||||
enc_ciphertext[NOTE_PLAINTEXT_SIZE..].into(),
|
||||
)
|
||||
.ok()?;
|
||||
|
||||
let (note, to) = domain.parse_note_plaintext_without_memo_ovk(&pk_d, &plaintext)?;
|
||||
let memo = domain.extract_memo(&plaintext);
|
||||
|
||||
// ZIP 212: Check that the esk provided to this function is consistent with the esk we can
|
||||
// derive from the note. This check corresponds to `ToScalar(PRF^{expand}_{rseed}([4]) = esk`
|
||||
// in https://zips.z.cash/protocol/protocol.pdf#decryptovk. (`ρ^opt = []` for Sapling.)
|
||||
if let Some(derived_esk) = D::derive_esk(¬e) {
|
||||
if (!derived_esk.ct_eq(&esk)).into() {
|
||||
return None;
|
||||
}
|
||||
}
|
||||
|
||||
if let NoteValidity::Valid =
|
||||
check_note_validity::<D>(¬e, &ephemeral_key, &output.cmstar_bytes())
|
||||
{
|
||||
Some((note, to, memo))
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue