serai/crypto/transcript/src/merlin.rs
2022-07-16 15:16:30 -05:00

45 lines
1.4 KiB
Rust

use core::fmt::{Debug, Formatter};
use crate::Transcript;
#[derive(Clone)]
pub struct MerlinTranscript(pub merlin::Transcript);
// Merlin doesn't implement Debug so provide a stub which won't panic
impl Debug for MerlinTranscript {
fn fmt(&self, _: &mut Formatter<'_>) -> Result<(), core::fmt::Error> {
Ok(())
}
}
impl Transcript for MerlinTranscript {
// Uses a challenge length of 64 bytes to support wide reduction on generated scalars
// From a security level standpoint, this should just be 32 bytes
// From a Merlin standpoint, this should be variable per call
// From a practical standpoint, this is a demo file not planned to be used and anything using
// this wrapper should be secure with this setting
type Challenge = [u8; 64];
fn new(name: &'static [u8]) -> Self {
MerlinTranscript(merlin::Transcript::new(name))
}
fn domain_separate(&mut self, label: &'static [u8]) {
self.append_message(b"dom-sep", label);
}
fn append_message(&mut self, label: &'static [u8], message: &[u8]) {
self.0.append_message(label, message);
}
fn challenge(&mut self, label: &'static [u8]) -> Self::Challenge {
let mut challenge = [0; 64];
self.0.challenge_bytes(label, &mut challenge);
challenge
}
fn rng_seed(&mut self, label: &'static [u8]) -> [u8; 32] {
let mut seed = [0; 32];
seed.copy_from_slice(&self.challenge(label)[.. 32]);
seed
}
}