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Add Sinsemilla constants

This commit is contained in:
therealyingtong 2021-03-17 17:17:01 +08:00
parent 7c8098ad43
commit ee969a64a8
2 changed files with 21 additions and 7 deletions
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11
src/primitives/sinsemilla.rs
View File

@ -6,11 +6,8 @@ use pasta_curves::pallas;
use crate::spec::extract_p;
const GROUP_HASH_Q: &str = "z.cash:SinsemillaQ";
const GROUP_HASH_S: &str = "z.cash:SinsemillaS";
const K: usize = 10;
const C: usize = 253;
mod constants;
pub use constants::*;
fn lebs2ip_k(bits: &[bool]) -> u32 {
assert!(bits.len() == K);
@ -81,7 +78,7 @@ impl<I: Iterator<Item = bool>> Iterator for Pad<I> {
#[allow(non_snake_case)]
fn Q(domain_prefix: &str) -> pallas::Point {
pallas::Point::hash_to_curve(GROUP_HASH_Q)(domain_prefix.as_bytes())
pallas::Point::hash_to_curve(Q_PERSONALIZATION)(domain_prefix.as_bytes())
}
/// `SinsemillaHashToPoint` from [§ 5.4.1.9][concretesinsemillahash].
@ -91,7 +88,7 @@ fn Q(domain_prefix: &str) -> pallas::Point {
pub(crate) fn hash_to_point(domain_prefix: &str, msg: impl Iterator<Item = bool>) -> pallas::Point {
let padded: Vec<_> = Pad::new(msg).collect();
let hasher_S = pallas::Point::hash_to_curve(GROUP_HASH_S);
let hasher_S = pallas::Point::hash_to_curve(S_PERSONALIZATION);
let S = |chunk: &[bool]| hasher_S(&lebs2ip_k(chunk).to_le_bytes());
padded

17
src/primitives/sinsemilla/constants.rs Normal file
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@ -0,0 +1,17 @@
//! Sinsemilla generators
/// Number of bits of each message piece in SinsemillaHashToPoint
pub const K: usize = 10;
/// The largest integer such that 2^c <= (r_P - 1) / 2, where r_P is the order
/// of Pallas.
pub const C: usize = 253;
// Sinsemilla Q generators
/// SWU hash-to-curve personalization for Sinsemilla Q generators
pub const Q_PERSONALIZATION: &str = "z.cash:SinsemillaQ";
// Sinsemilla S generators
/// SWU hash-to-curve personalization for Sinsemilla S generators
pub const S_PERSONALIZATION: &str = "z.cash:SinsemillaS";