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use crate::memsec::Scrubbed as _;
use cryptoxide::{hmac::Hmac, pbkdf2::pbkdf2, sha2::Sha512};
use rand_chacha::ChaChaRng;
use rand_core::{CryptoRng, RngCore, SeedableRng};
use std::{
fmt::{self, Debug, Display, Formatter},
str::FromStr,
};
#[derive(Clone)]
pub struct Seed([u8; Self::SIZE]);
impl Seed {
pub const SIZE: usize = 32;
pub fn generate<RNG>(rng: &mut RNG) -> Self
where
RNG: RngCore + CryptoRng,
{
let mut bytes = [0; Self::SIZE];
rng.fill_bytes(&mut bytes);
Self(bytes)
}
pub fn derive_from_key<K, P>(key: K, password: P) -> Self
where
K: AsRef<[u8]>,
P: AsRef<[u8]>,
{
debug_assert!(
key.as_ref().len() >= 32,
"It is highly unsafe to use key with less than 32bytes"
);
let iteration = 1_000_000;
let mut bytes = [0; Self::SIZE];
let mut mac = Hmac::new(Sha512::new(), password.as_ref());
pbkdf2(&mut mac, key.as_ref(), iteration, &mut bytes);
Self(bytes)
}
pub fn into_rand_chacha(self) -> ChaChaRng {
ChaChaRng::from_seed(self.0)
}
}
impl Drop for Seed {
fn drop(&mut self) {
self.0.scrub()
}
}
impl Display for Seed {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Display::fmt(&hex::encode(&self.0), f)
}
}
impl Debug for Seed {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
f.debug_tuple("Seed").field(&hex::encode(&self.0)).finish()
}
}
impl AsRef<[u8]> for Seed {
fn as_ref(&self) -> &[u8] {
&self.0
}
}
impl FromStr for Seed {
type Err = hex::FromHexError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let mut bytes = [0; Self::SIZE];
hex::decode_to_slice(s, &mut bytes)?;
Ok(Self(bytes))
}
}
impl From<[u8; Self::SIZE]> for Seed {
fn from(seed: [u8; Self::SIZE]) -> Self {
Self(seed)
}
}
#[cfg(test)]
mod tests {
use super::*;
use quickcheck::{Arbitrary, Gen};
impl Arbitrary for Seed {
fn arbitrary(g: &mut Gen) -> Self {
let mut bytes = [0; Self::SIZE];
bytes.iter_mut().for_each(|byte| {
*byte = u8::arbitrary(g);
});
Self(bytes)
}
}
}