mirror of https://github.com/zcash/orchard.git
85 lines
2.3 KiB
Rust
85 lines
2.3 KiB
Rust
use group::GroupEncoding;
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use pasta_curves::pallas;
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use crate::{
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keys::FullViewingKey,
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spec::{prf_expand, to_base, to_scalar},
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value::NoteValue,
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Address,
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};
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mod commitment;
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pub use self::commitment::NoteCommitment;
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mod nullifier;
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pub use self::nullifier::Nullifier;
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/// The ZIP 212 seed randomness for a note.
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#[derive(Debug)]
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struct RandomSeed([u8; 32]);
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impl RandomSeed {
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/// Defined in [Zcash Protocol Spec § 4.7.3: Sending Notes (Orchard)][orchardsend].
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///
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/// [orchardsend]: https://zips.z.cash/protocol/nu5.pdf#orchardsend
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fn psi(&self) -> pallas::Base {
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to_base(prf_expand(&self.0, &[0x09]))
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}
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/// Defined in [Zcash Protocol Spec § 4.7.3: Sending Notes (Orchard)][orchardsend].
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///
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/// [orchardsend]: https://zips.z.cash/protocol/nu5.pdf#orchardsend
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fn esk(&self) -> pallas::Scalar {
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to_scalar(prf_expand(&self.0, &[0x04]))
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}
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}
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/// A discrete amount of funds received by an address.
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#[derive(Debug)]
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pub struct Note {
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/// The recipient of the funds.
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recipient: Address,
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/// The value of this note.
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value: NoteValue,
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/// A unique creation ID for this note.
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///
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/// This is set to the nullifier of the note that was spent in the [`Action`] that
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/// created this note.
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///
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/// [`Action`]: crate::bundle::Action
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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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}
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impl Note {
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/// Derives the commitment to this note.
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///
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/// Defined in [Zcash Protocol Spec § 3.2: Notes][notes].
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///
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/// [notes]: https://zips.z.cash/protocol/nu5.pdf#notes
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pub fn commitment(&self) -> NoteCommitment {
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let g_d = self.recipient.g_d();
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// `Note` will always have a note commitment by construction.
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NoteCommitment::derive(
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g_d.to_bytes(),
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self.recipient.pk_d().to_bytes(),
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self.value,
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self.rho.0,
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self.rseed.psi(),
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(&self.rseed).into(),
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)
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.unwrap()
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}
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/// Derives the nullifier for this note.
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pub fn nullifier(&self, fvk: &FullViewingKey) -> Nullifier {
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Nullifier::derive(fvk.nk(), self.rho.0, self.rseed.psi(), self.commitment())
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}
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}
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/// An encrypted note.
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#[derive(Debug)]
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pub struct EncryptedNote;
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