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Add 2A precomputation to jubjub parameters.

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This commit is contained in:
Sean Bowe
2017-12-14 11:34:57 -07:00
parent 6b43a4ed10
commit 8c4433ee82
2 changed files with 19 additions and 1 deletions
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12
src/jubjub/mod.rs
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@@ -16,6 +16,7 @@
use pairing::{
Engine,
Field,
PrimeField,
SqrtField
};
@@ -39,6 +40,7 @@ pub trait JubjubEngine: Engine {
pub trait JubjubParams<E: JubjubEngine>: Sized {
fn edwards_d(&self) -> &E::Fr;
fn montgomery_a(&self) -> &E::Fr;
fn montgomery_2a(&self) -> &E::Fr;
fn scale(&self) -> &E::Fr;
}
@@ -55,22 +57,30 @@ impl JubjubEngine for Bls12 {
pub struct JubjubBls12 {
edwards_d: Fr,
montgomery_a: Fr,
montgomery_2a: Fr,
scale: Fr
}
impl JubjubParams<Bls12> for JubjubBls12 {
fn edwards_d(&self) -> &Fr { &self.edwards_d }
fn montgomery_a(&self) -> &Fr { &self.montgomery_a }
fn montgomery_2a(&self) -> &Fr { &self.montgomery_2a }
fn scale(&self) -> &Fr { &self.scale }
}
impl JubjubBls12 {
pub fn new() -> Self {
let montgomery_a = Fr::from_str("40962").unwrap();
let mut montgomery_2a = montgomery_a;
montgomery_2a.double();
JubjubBls12 {
// d = -(10240/10241)
edwards_d: Fr::from_str("19257038036680949359750312669786877991949435402254120286184196891950884077233").unwrap(),
// A = 40962
montgomery_a: Fr::from_str("40962").unwrap(),
montgomery_a: montgomery_a,
// 2A = 2.A
montgomery_2a: montgomery_2a,
// scaling factor = sqrt(4 / (a - d))
scale: Fr::from_str("17814886934372412843466061268024708274627479829237077604635722030778476050649").unwrap()
}