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use crate::SecretKey;
use bls12_381_plus::{G1Affine, G1Projective};
use group::Curve;
use serde::{Deserialize, Serialize};
use signature_core::lib::*;
use subtle::Choice;
#[derive(Clone, Debug, Eq, PartialEq, Deserialize, Serialize)]
pub struct MessageGenerators {
#[serde(with = "VecSerializer")]
pub(crate) y: Vec<G1Projective, 128>,
}
impl Default for MessageGenerators {
fn default() -> Self {
Self { y: Vec::new() }
}
}
impl From<&SecretKey> for MessageGenerators {
fn from(sk: &SecretKey) -> Self {
let mut y = Vec::new();
for s_y in &sk.y {
y.push(G1Projective::generator() * s_y)
.expect("allocate more space");
}
Self { y }
}
}
impl MessageGenerators {
const POINT_SIZE: usize = 48;
pub fn is_valid(&self) -> Choice {
let mut res = Choice::from(1u8);
for y in &self.y {
res &= !y.is_identity();
}
res
}
pub fn is_invalid(&self) -> Choice {
let mut res = Choice::from(0u8);
for y in &self.y {
res |= y.is_identity();
}
res
}
pub fn to_bytes(&self, buffer: &mut [u8]) {
let mut offset = 0;
let mut end = Self::POINT_SIZE;
for y in &self.y {
buffer[offset..end].copy_from_slice(&y.to_affine().to_compressed()[..]);
offset = end;
end += Self::POINT_SIZE;
}
}
pub fn from_bytes<B: AsRef<[u8]>>(bytes: B) -> Option<Self> {
const MIN_SIZE: usize = MessageGenerators::POINT_SIZE;
let buffer = bytes.as_ref();
if buffer.len() % Self::POINT_SIZE != 0 {
return None;
}
if buffer.len() < MIN_SIZE {
return None;
}
fn from_be_bytes(d: &[u8]) -> G1Projective {
use core::convert::TryFrom;
let t = <[u8; MessageGenerators::POINT_SIZE]>::try_from(d).expect("invalid length");
G1Affine::from_compressed(&t)
.map(G1Projective::from)
.unwrap()
}
let y_cnt = buffer.len() / Self::POINT_SIZE;
let mut offset = 0;
let mut end = Self::POINT_SIZE;
let mut y = Vec::new();
for _ in 0..y_cnt {
if y.push(from_be_bytes(&buffer[offset..end])).is_err() {
return None;
}
offset = end;
end += Self::POINT_SIZE;
}
Some(Self { y })
}
}