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Merge pull request #130 from nuttycom/use_value_commitment_constants 

Use constants for value commitment hash-to-curve.
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str4d 2021-06-24 01:21:25 +01:00 committed by GitHub
parent 71756cffda f22907a4d7
commit af335ff7de
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2 changed files with 15 additions and 4 deletions
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6
src/constants.rs
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@ -45,6 +45,12 @@ pub const KEY_DIVERSIFICATION_PERSONALIZATION: &str = "z.cash:Orchard-gd";
/// SWU hash-to-curve personalization for the value commitment generator
pub const VALUE_COMMITMENT_PERSONALIZATION: &str = "z.cash:Orchard-cv";
/// SWU hash-to-curve value for the value commitment generator
pub const VALUE_COMMITMENT_V_BYTES: [u8; 1] = *b"v";
/// SWU hash-to-curve value for the value commitment generator
pub const VALUE_COMMITMENT_R_BYTES: [u8; 1] = *b"r";
/// SWU hash-to-curve personalization for the note commitment generator
pub const NOTE_COMMITMENT_PERSONALIZATION: &str = "z.cash:Orchard-NoteCommit";

13
src/value.rs
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@ -29,7 +29,12 @@ use pasta_curves::{
use rand::RngCore;
use subtle::CtOption;
use crate::primitives::redpallas::{self, Binding};
use crate::{
constants::{
VALUE_COMMITMENT_PERSONALIZATION, VALUE_COMMITMENT_R_BYTES, VALUE_COMMITMENT_V_BYTES,
},
primitives::redpallas::{self, Binding},
};
use std::ops::RangeInclusive;
@ -230,9 +235,9 @@ impl ValueCommitment {
/// [concretehomomorphiccommit]: https://zips.z.cash/protocol/nu5.pdf#concretehomomorphiccommit
#[allow(non_snake_case)]
pub(crate) fn derive(value: ValueSum, rcv: ValueCommitTrapdoor) -> Self {
let hasher = pallas::Point::hash_to_curve("z.cash:Orchard-cv");
let V = hasher(b"v");
let R = hasher(b"r");
let hasher = pallas::Point::hash_to_curve(VALUE_COMMITMENT_PERSONALIZATION);
let V = hasher(&VALUE_COMMITMENT_V_BYTES);
let R = hasher(&VALUE_COMMITMENT_R_BYTES);
let abs_value = u64::try_from(value.0.abs()).expect("value must be in valid range");
let value = if value.0.is_negative() {