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use crate::keys::spend::stealth;
use crate::{
permutation, JubJubAffine, JubJubExtended, JubJubScalar, PublicSpendKey,
SecretSpendKey,
};
use dusk_bytes::{DeserializableSlice, Error, HexDebug, Serializable};
use dusk_jubjub::GENERATOR_EXTENDED;
use subtle::{Choice, ConstantTimeEq};
#[derive(Clone, Copy, HexDebug)]
pub struct ViewKey {
a: JubJubScalar,
B: JubJubExtended,
}
impl ConstantTimeEq for ViewKey {
fn ct_eq(&self, other: &Self) -> Choice {
self.B.ct_eq(&other.B)
}
}
impl PartialEq for ViewKey {
fn eq(&self, other: &Self) -> bool {
self.a == other.a && self.ct_eq(other).into()
}
}
impl Eq for ViewKey {}
impl ViewKey {
pub fn new(a: JubJubScalar, B: JubJubExtended) -> Self {
Self { a, B }
}
pub fn public_spend_key(&self) -> PublicSpendKey {
let A = GENERATOR_EXTENDED * self.a;
PublicSpendKey::new(A, self.B)
}
pub fn a(&self) -> &JubJubScalar {
&self.a
}
pub fn B(&self) -> &JubJubExtended {
&self.B
}
pub fn owns(&self, owner: &impl stealth::Ownable) -> bool {
let sa = owner.stealth_address();
let aR = sa.R() * self.a();
let aR = permutation::hash(&aR);
let aR = GENERATOR_EXTENDED * aR;
let pk_r = aR + self.B();
sa.address() == &pk_r
}
}
impl From<SecretSpendKey> for ViewKey {
fn from(secret: SecretSpendKey) -> Self {
secret.view_key()
}
}
impl From<&SecretSpendKey> for ViewKey {
fn from(secret: &SecretSpendKey) -> Self {
secret.view_key()
}
}
impl Serializable<64> for ViewKey {
type Error = Error;
fn to_bytes(&self) -> [u8; 64] {
let mut bytes = [0u8; 64];
bytes[..32].copy_from_slice(&self.a.to_bytes());
bytes[32..].copy_from_slice(&JubJubAffine::from(&self.B).to_bytes());
bytes
}
fn from_bytes(buf: &[u8; 64]) -> Result<Self, Self::Error> {
let a = JubJubScalar::from_slice(&buf[..32])?;
let B = JubJubExtended::from(JubJubAffine::from_slice(&buf[32..])?);
Ok(Self { a, B })
}
}