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use bellman::pairing::ff::{
Field,
PrimeField,
PrimeFieldRepr
};
use constants;
use group_hash::group_hash;
use pedersen_hash::{
pedersen_hash,
Personalization
};
use byteorder::{
LittleEndian,
WriteBytesExt
};
use jubjub::{
JubjubEngine,
JubjubParams,
edwards,
PrimeOrder,
FixedGenerators
};
use blake2_rfc::blake2s::Blake2s;
#[derive(Clone)]
pub struct ValueCommitment<E: JubjubEngine> {
pub value: u64,
pub randomness: E::Fs
}
impl<E: JubjubEngine> ValueCommitment<E> {
pub fn cm(
&self,
params: &E::Params
) -> edwards::Point<E, PrimeOrder>
{
params.generator(FixedGenerators::ValueCommitmentValue)
.mul(self.value, params)
.add(
¶ms.generator(FixedGenerators::ValueCommitmentRandomness)
.mul(self.randomness, params),
params
)
}
}
#[derive(Clone)]
pub struct ProofGenerationKey<E: JubjubEngine> {
pub ak: edwards::Point<E, PrimeOrder>,
pub nsk: E::Fs
}
impl<E: JubjubEngine> ProofGenerationKey<E> {
pub fn into_viewing_key(&self, params: &E::Params) -> ViewingKey<E> {
ViewingKey {
ak: self.ak.clone(),
nk: params.generator(FixedGenerators::ProofGenerationKey)
.mul(self.nsk, params)
}
}
}
pub struct ViewingKey<E: JubjubEngine> {
pub ak: edwards::Point<E, PrimeOrder>,
pub nk: edwards::Point<E, PrimeOrder>
}
impl<E: JubjubEngine> ViewingKey<E> {
pub fn rk(
&self,
ar: E::Fs,
params: &E::Params
) -> edwards::Point<E, PrimeOrder> {
self.ak.add(
¶ms.generator(FixedGenerators::SpendingKeyGenerator)
.mul(ar, params),
params
)
}
pub fn ivk(&self) -> E::Fs {
let mut preimage = [0; 64];
self.ak.write(&mut preimage[0..32]).unwrap();
self.nk.write(&mut preimage[32..64]).unwrap();
let mut h = Blake2s::with_params(32, &[], &[], constants::CRH_IVK_PERSONALIZATION);
h.update(&preimage);
let mut h = h.finalize().as_ref().to_vec();
h[31] &= 0b0000_0111;
let mut e = <E::Fs as PrimeField>::Repr::default();
e.read_le(&h[..]).unwrap();
E::Fs::from_repr(e).expect("should be a valid scalar")
}
pub fn into_payment_address(
&self,
diversifier: Diversifier,
params: &E::Params
) -> Option<PaymentAddress<E>>
{
diversifier.g_d(params).map(|g_d| {
let pk_d = g_d.mul(self.ivk(), params);
PaymentAddress {
pk_d: pk_d,
diversifier: diversifier
}
})
}
}
#[derive(Copy, Clone)]
pub struct Diversifier(pub [u8; 11]);
impl Diversifier {
pub fn g_d<E: JubjubEngine>(
&self,
params: &E::Params
) -> Option<edwards::Point<E, PrimeOrder>>
{
group_hash::<E>(&self.0, constants::KEY_DIVERSIFICATION_PERSONALIZATION, params)
}
}
#[derive(Clone)]
pub struct PaymentAddress<E: JubjubEngine> {
pub pk_d: edwards::Point<E, PrimeOrder>,
pub diversifier: Diversifier
}
impl<E: JubjubEngine> PaymentAddress<E> {
pub fn g_d(
&self,
params: &E::Params
) -> Option<edwards::Point<E, PrimeOrder>>
{
self.diversifier.g_d(params)
}
pub fn create_note(
&self,
value: u64,
randomness: E::Fs,
params: &E::Params
) -> Option<Note<E>>
{
self.g_d(params).map(|g_d| {
Note {
value: value,
r: randomness,
g_d: g_d,
pk_d: self.pk_d.clone()
}
})
}
}
pub struct Note<E: JubjubEngine> {
pub value: u64,
pub g_d: edwards::Point<E, PrimeOrder>,
pub pk_d: edwards::Point<E, PrimeOrder>,
pub r: E::Fs
}
impl<E: JubjubEngine> Note<E> {
pub fn uncommitted() -> E::Fr {
E::Fr::one()
}
fn cm_full_point(&self, params: &E::Params) -> edwards::Point<E, PrimeOrder>
{
let mut note_contents = vec![];
(&mut note_contents).write_u64::<LittleEndian>(self.value).unwrap();
self.g_d.write(&mut note_contents).unwrap();
self.pk_d.write(&mut note_contents).unwrap();
assert_eq!(note_contents.len(), 32 + 32 + 8);
let hash_of_contents = pedersen_hash(
Personalization::NoteCommitment,
note_contents.into_iter()
.flat_map(|byte| {
(0..8).map(move |i| ((byte >> i) & 1) == 1)
}),
params
);
params.generator(FixedGenerators::NoteCommitmentRandomness)
.mul(self.r, params)
.add(&hash_of_contents, params)
}
pub fn nf(
&self,
viewing_key: &ViewingKey<E>,
position: u64,
params: &E::Params
) -> Vec<u8>
{
let rho = self
.cm_full_point(params)
.add(
¶ms.generator(FixedGenerators::NullifierPosition)
.mul(position, params),
params
);
let mut nf_preimage = [0u8; 64];
viewing_key.nk.write(&mut nf_preimage[0..32]).unwrap();
rho.write(&mut nf_preimage[32..64]).unwrap();
let mut h = Blake2s::with_params(32, &[], &[], constants::PRF_NF_PERSONALIZATION);
h.update(&nf_preimage);
h.finalize().as_ref().to_vec()
}
pub fn cm(&self, params: &E::Params) -> E::Fr
{
self.cm_full_point(params).into_xy().0
}
}