mirror of https://github.com/zcash/orchard.git
zsa-note-encryption: introduce AssetType and encode and decode it in note plaintexts
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parent
0d7ecad8e9
commit
96442412af
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@ -23,6 +23,7 @@ use crate::{
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tree::{Anchor, MerklePath},
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value::{self, NoteValue, OverflowError, ValueCommitTrapdoor, ValueCommitment, ValueSum},
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};
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use crate::note::AssetType;
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const MIN_ACTIONS: usize = 2;
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@ -150,8 +151,9 @@ impl ActionInfo {
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let ak: SpendValidatingKey = self.spend.fvk.clone().into();
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let alpha = pallas::Scalar::random(&mut rng);
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let rk = ak.randomize(&alpha);
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let asset_type = self.spend.note.asset_type();
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let note = Note::new(self.output.recipient, self.output.value, nf_old, &mut rng);
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let note = Note::new(self.output.recipient, self.output.value, nf_old, &mut rng, asset_type);
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let cm_new = note.commitment();
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let cmx = cm_new.into();
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@ -30,6 +30,9 @@ pub const VALUE_COMMITMENT_R_BYTES: [u8; 1] = *b"r";
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/// SWU hash-to-curve personalization for the note commitment generator
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pub const NOTE_COMMITMENT_PERSONALIZATION: &str = "z.cash:Orchard-NoteCommit";
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/// SWU hash-to-curve personalization for the ZSA note commitment generator
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pub const NOTE_ZSA_COMMITMENT_PERSONALIZATION: &str = "z.cash:ZSA-NoteCommit";
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/// SWU hash-to-curve personalization for the IVK commitment generator
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pub const COMMIT_IVK_PERSONALIZATION: &str = "z.cash:Orchard-CommitIvk";
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@ -967,6 +967,7 @@ mod tests {
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value::NoteValue,
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Note,
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};
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use crate::note::AssetType;
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#[test]
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fn spend_validating_key_from_bytes() {
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@ -1049,6 +1050,7 @@ mod tests {
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NoteValue::from_raw(tv.note_v),
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rho,
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RandomSeed::from_bytes(tv.note_rseed, &rho).unwrap(),
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AssetType::ZEC,
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);
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let cmx: ExtractedNoteCommitment = note.commitment().into();
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40
src/note.rs
40
src/note.rs
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@ -79,6 +79,28 @@ impl RandomSeed {
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}
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}
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/// The ID of ZEC or a ZSA asset.
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#[derive(Debug, Copy, Clone)]
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pub enum AssetType {
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/// Represents the native asset of the protocol, a.k.a. ZEC.
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ZEC,
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/// Represents a user-defined asset.
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// TODO: check the uniqueness of the encoding.
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Asset(ZSAType),
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}
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impl AssetType {
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/// Parse the encoding of a ZSA asset type.
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pub fn from_bytes(bytes: &[u8; 32]) -> CtOption<Self> {
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pallas::Affine::from_bytes(bytes)
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.map(|t| AssetType::Asset(ZSAType(t)))
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}
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}
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/// The ID of a ZSA asset. This type cannot represent native ZEC.
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#[derive(Debug, Copy, Clone)]
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pub struct ZSAType(pub(crate) pallas::Affine);
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/// A discrete amount of funds received by an address.
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#[derive(Debug, Copy, Clone)]
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pub struct Note {
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@ -95,6 +117,9 @@ pub struct Note {
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rho: Nullifier,
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/// The seed randomness for various note components.
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rseed: RandomSeed,
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// TODO: merge with the value field to make it impossible to ignore?
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// TODO: use a constant-time structure (like CtOption)?
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asset_type: AssetType,
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}
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impl PartialEq for Note {
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@ -113,12 +138,14 @@ impl Note {
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value: NoteValue,
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rho: Nullifier,
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rseed: RandomSeed,
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asset_type: AssetType,
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) -> Self {
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Note {
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recipient,
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value,
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rho,
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rseed,
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asset_type,
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}
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}
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@ -132,6 +159,7 @@ impl Note {
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value: NoteValue,
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rho: Nullifier,
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mut rng: impl RngCore,
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asset_type: AssetType,
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) -> Self {
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loop {
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let note = Note {
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@ -139,6 +167,7 @@ impl Note {
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value,
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rho,
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rseed: RandomSeed::random(&mut rng, &rho),
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asset_type,
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};
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if note.commitment_inner().is_some().into() {
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break note;
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@ -158,12 +187,14 @@ impl Note {
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let sk = SpendingKey::random(rng);
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let fvk: FullViewingKey = (&sk).into();
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let recipient = fvk.address_at(0u32, Scope::External);
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let asset_type = AssetType::ZEC;
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let note = Note::new(
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recipient,
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NoteValue::zero(),
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rho.unwrap_or_else(|| Nullifier::dummy(rng)),
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rng,
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asset_type,
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);
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(sk, fvk, note)
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@ -179,6 +210,11 @@ impl Note {
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self.value
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}
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/// Returns the asset type of this note.
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pub fn asset_type(&self) -> AssetType {
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self.asset_type
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}
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/// Returns the rseed value of this note.
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pub(crate) fn rseed(&self) -> &RandomSeed {
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&self.rseed
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@ -223,6 +259,7 @@ impl Note {
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self.rho.0,
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self.rseed.psi(&self.rho),
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self.rseed.rcm(&self.rho),
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self.asset_type,
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)
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}
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@ -269,7 +306,7 @@ pub mod testing {
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address::testing::arb_address, note::nullifier::testing::arb_nullifier, value::NoteValue,
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};
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use super::{Note, RandomSeed};
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use super::{AssetType, Note, RandomSeed};
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prop_compose! {
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/// Generate an arbitrary random seed
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@ -290,6 +327,7 @@ pub mod testing {
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value,
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rho,
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rseed,
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asset_type: AssetType::ZEC,
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}
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}
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}
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@ -11,6 +11,9 @@ use crate::{
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spec::extract_p,
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value::NoteValue,
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};
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use crate::note::AssetType;
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use group::GroupEncoding;
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use crate::constants::fixed_bases::NOTE_ZSA_COMMITMENT_PERSONALIZATION;
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#[derive(Clone, Debug)]
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pub(crate) struct NoteCommitTrapdoor(pub(super) pallas::Scalar);
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@ -44,16 +47,57 @@ impl NoteCommitment {
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rho: pallas::Base,
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psi: pallas::Base,
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rcm: NoteCommitTrapdoor,
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asset_type: AssetType,
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) -> CtOption<Self> {
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let domain = sinsemilla::CommitDomain::new(NOTE_COMMITMENT_PERSONALIZATION);
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let g_d_bits = BitArray::<_, Lsb0>::new(g_d);
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let pk_d_bits = BitArray::<_, Lsb0>::new(pk_d);
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let v_bits = v.to_le_bits();
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let rho_bits = rho.to_le_bits();
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let psi_bits = psi.to_le_bits();
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let zec_note_bits = iter::empty()
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.chain(g_d_bits.iter().by_vals())
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.chain(pk_d_bits.iter().by_vals())
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.chain(v_bits.iter().by_vals())
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.chain(rho_bits.iter().by_vals().take(L_ORCHARD_BASE))
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.chain(psi_bits.iter().by_vals().take(L_ORCHARD_BASE));
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// TODO: make this match constant-time.
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match asset_type {
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// Commit to ZEC notes as per the Orchard protocol.
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AssetType::ZEC =>
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Self::commit(
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NOTE_COMMITMENT_PERSONALIZATION,
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zec_note_bits,
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rcm,
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),
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// Commit to non-ZEC notes as per the ZSA protocol.
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AssetType::Asset(zsa_type) => {
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// Append the asset type to the Orchard note encoding.
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let encoded_type = BitArray::<_, Lsb0>::new(zsa_type.0.to_bytes());
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let zsa_note_bits = zec_note_bits
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.chain(encoded_type.iter().by_vals());
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// Commit in a different domain than Orchard notes.
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Self::commit(
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NOTE_ZSA_COMMITMENT_PERSONALIZATION,
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zsa_note_bits,
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rcm,
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)
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},
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}
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}
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fn commit(
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personalization: &str,
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bits: impl Iterator<Item = bool>,
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rcm: NoteCommitTrapdoor,
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) -> CtOption<Self> {
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let domain = sinsemilla::CommitDomain::new(personalization);
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domain
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.commit(
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iter::empty()
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.chain(BitArray::<_, Lsb0>::new(g_d).iter().by_vals())
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.chain(BitArray::<_, Lsb0>::new(pk_d).iter().by_vals())
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.chain(v.to_le_bits().iter().by_vals())
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.chain(rho.to_le_bits().iter().by_vals().take(L_ORCHARD_BASE))
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.chain(psi.to_le_bits().iter().by_vals().take(L_ORCHARD_BASE)),
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bits,
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&rcm.0,
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)
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.map(NoteCommitment)
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@ -4,11 +4,7 @@ use core::fmt;
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use blake2b_simd::{Hash, Params};
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use group::ff::PrimeField;
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use zcash_note_encryption::{
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BatchDomain, Domain, EphemeralKeyBytes, NotePlaintextBytes, OutPlaintextBytes,
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OutgoingCipherKey, ShieldedOutput, COMPACT_NOTE_SIZE, ENC_CIPHERTEXT_SIZE, NOTE_PLAINTEXT_SIZE,
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OUT_PLAINTEXT_SIZE,
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};
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use zcash_note_encryption::{BatchDomain, Domain, EphemeralKeyBytes, NotePlaintextBytes, OutPlaintextBytes, OutgoingCipherKey, ShieldedOutput, COMPACT_NOTE_SIZE, COMPACT_ZSA_NOTE_SIZE, ENC_CIPHERTEXT_SIZE, NOTE_PLAINTEXT_SIZE, OUT_PLAINTEXT_SIZE, MEMO_SIZE};
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use crate::{
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action::Action,
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@ -21,6 +17,9 @@ use crate::{
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value::{NoteValue, ValueCommitment},
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Address, Note,
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};
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use crate::note::AssetType;
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use group::GroupEncoding;
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use subtle::CtOption;
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const PRF_OCK_ORCHARD_PERSONALIZATION: &[u8; 16] = b"Zcash_Orchardock";
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@ -57,12 +56,11 @@ fn orchard_parse_note_plaintext_without_memo<F>(
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where
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F: FnOnce(&Diversifier) -> Option<DiversifiedTransmissionKey>,
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{
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assert!(plaintext.len() >= COMPACT_NOTE_SIZE);
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assert!(plaintext.len() >= COMPACT_NOTE_SIZE); // TODO: don’t panic, return None.
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// Check note plaintext version
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if plaintext[0] != 0x02 {
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return None;
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}
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// and parse the asset type accordingly.
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let asset_type = parse_version_and_asset_type(plaintext)?;
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// The unwraps below are guaranteed to succeed by the assertion above
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let diversifier = Diversifier::from_bytes(plaintext[1..12].try_into().unwrap());
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@ -75,10 +73,23 @@ where
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let pk_d = get_validated_pk_d(&diversifier)?;
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let recipient = Address::from_parts(diversifier, pk_d);
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let note = Note::from_parts(recipient, value, domain.rho, rseed);
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let note = Note::from_parts(recipient, value, domain.rho, rseed, asset_type);
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Some((note, recipient))
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}
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fn parse_version_and_asset_type(plaintext: &[u8]) -> Option<AssetType> {
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// TODO: make this constant-time?
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match plaintext[0] {
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0x02 => Some(AssetType::ZEC),
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0x03 if plaintext.len() >= COMPACT_ZSA_NOTE_SIZE => {
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let bytes = &plaintext[COMPACT_NOTE_SIZE..COMPACT_ZSA_NOTE_SIZE].try_into().unwrap();
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AssetType::from_bytes(bytes).into()
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}
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_ => None,
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}
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}
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/// Orchard-specific note encryption logic.
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#[derive(Debug)]
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pub struct OrchardDomain {
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@ -107,7 +118,7 @@ impl Domain for OrchardDomain {
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type ValueCommitment = ValueCommitment;
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type ExtractedCommitment = ExtractedNoteCommitment;
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type ExtractedCommitmentBytes = [u8; 32];
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type Memo = [u8; 512]; // TODO use a more interesting type
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type Memo = [u8; MEMO_SIZE]; // TODO use a more interesting type
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fn derive_esk(note: &Self::Note) -> Option<Self::EphemeralSecretKey> {
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Some(note.esk())
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@ -148,11 +159,24 @@ impl Domain for OrchardDomain {
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memo: &Self::Memo,
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) -> NotePlaintextBytes {
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let mut np = [0; NOTE_PLAINTEXT_SIZE];
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np[0] = 0x02;
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np[0] = match note.asset_type() {
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AssetType::ZEC => 0x02,
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AssetType::Asset(_) => 0x03,
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};
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np[1..12].copy_from_slice(note.recipient().diversifier().as_array());
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np[12..20].copy_from_slice(¬e.value().to_bytes());
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np[20..52].copy_from_slice(note.rseed().as_bytes());
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np[52..].copy_from_slice(memo);
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match note.asset_type() {
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AssetType::ZEC => {
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np[52..].copy_from_slice(memo);
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},
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AssetType::Asset(zsa_type) => {
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np[52..84].copy_from_slice(&zsa_type.0.to_bytes());
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let short_memo = &memo[0..memo.len()-32];
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np[84..].copy_from_slice(short_memo);
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// TODO: handle full-size memo or make short_memo explicit.
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}
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};
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NotePlaintextBytes(np)
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}
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@ -327,6 +351,7 @@ mod tests {
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value::{NoteValue, ValueCommitment},
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Address, Note,
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};
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use crate::note::AssetType;
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#[test]
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fn test_vectors() {
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@ -369,7 +394,8 @@ mod tests {
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assert_eq!(ock.as_ref(), tv.ock);
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let recipient = Address::from_parts(d, pk_d);
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let note = Note::from_parts(recipient, value, rho, rseed);
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let asset_type = AssetType::ZEC; // TODO: from data.
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let note = Note::from_parts(recipient, value, rho, rseed, asset_type);
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assert_eq!(ExtractedNoteCommitment::from(note.commitment()), cmx);
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let action = Action::from_parts(
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