85 lines
2.5 KiB
Rust
85 lines
2.5 KiB
Rust
use std::{convert::TryFrom, marker::PhantomData};
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use crate::{
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Binding, Error, PublicKey, PublicKeyBytes, Randomizer, Scalar, SigType, Signature, SpendAuth,
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};
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use rand_core::{CryptoRng, RngCore};
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/// A RedJubJub secret key.
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#[derive(Copy, Clone, Debug)]
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pub struct SecretKey<T: SigType> {
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sk: Scalar,
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pk: PublicKey<T>,
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}
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impl<T: SigType> From<SecretKey<T>> for [u8; 32] {
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fn from(sk: SecretKey<T>) -> [u8; 32] {
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sk.sk.to_bytes()
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}
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}
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impl<T: SigType> From<[u8; 32]> for SecretKey<T> {
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fn from(bytes: [u8; 32]) -> Self {
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let sk = {
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// XXX-jubjub: would be nice to unconditionally deser
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// This incantation ensures deserialization is infallible.
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let mut wide = [0; 64];
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wide[0..32].copy_from_slice(&bytes);
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Scalar::from_bytes_wide(&wide)
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};
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let pk = PublicKey::from_secret(&sk);
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SecretKey { sk, pk }
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}
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}
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impl<T: SigType> SecretKey<T> {
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/// Generate a new secret key.
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pub fn new<R: RngCore + CryptoRng>(mut rng: R) -> SecretKey<T> {
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let sk = {
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let mut bytes = [0; 64];
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rng.fill_bytes(&mut bytes);
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Scalar::from_bytes_wide(&bytes)
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};
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let pk = PublicKey::from_secret(&sk);
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SecretKey { sk, pk }
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}
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/// Randomize this public key with the given `randomizer`.
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pub fn randomize(&self, randomizer: Randomizer) -> PublicKey<T> {
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unimplemented!();
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}
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/// Create a signature of type `T` on `msg` using this `SecretKey`.
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// Similar to signature::Signer but without boxed errors.
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pub fn sign<R: RngCore + CryptoRng>(&self, mut rng: R, msg: &[u8]) -> Signature<T> {
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use crate::HStar;
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// Choose a byte sequence uniformly at random of length
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// (\ell_H + 128)/8 bytes. For RedJubjub this is (512 + 128)/8 = 80.
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let random_bytes = {
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let mut bytes = [0; 80];
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rng.fill_bytes(&mut bytes);
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bytes
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};
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let nonce = HStar::default()
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.update(&random_bytes[..])
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.update(&self.pk.bytes.bytes[..]) // XXX ugly
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.update(msg)
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.finalize();
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let r_bytes = jubjub::AffinePoint::from(&T::basepoint() * &nonce).to_bytes();
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let c = HStar::default()
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.update(&r_bytes[..])
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.update(&self.pk.bytes.bytes[..]) // XXX ugly
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.update(msg)
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.finalize();
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let s_bytes = (&nonce + &(&c * &self.sk)).to_bytes();
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Signature::from_parts(r_bytes, s_bytes)
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}
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}
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