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// -*- mode: rust; -*-
//
// This file is part of schnorrkel.
// Copyright (c) 2019 Isis Lovecruft and Web 3 Foundation
// See LICENSE for licensing information.
//
// Authors:
// - Isis Agora Lovecruft <isis@patternsinthevoid.net>
// - Jeff Burdges <jeff@web3.foundation>
//! ### Schnorr signatures on the 2-torsion free subgroup of ed25519, as provided by the Ristretto point compression.
use core::convert::AsRef;
use core::fmt::{Debug};
use rand_core::{RngCore,CryptoRng};
use curve25519_dalek::constants;
use curve25519_dalek::ristretto::{CompressedRistretto,RistrettoPoint};
use curve25519_dalek::scalar::Scalar;
use subtle::{Choice,ConstantTimeEq};
use zeroize::Zeroize;
use crate::scalars;
use crate::points::RistrettoBoth;
use crate::errors::{SignatureError,SignatureResult};
/// The length of a Ristretto Schnorr `MiniSecretKey`, in bytes.
pub const MINI_SECRET_KEY_LENGTH: usize = 32;
/// The length of a Ristretto Schnorr `PublicKey`, in bytes.
pub const PUBLIC_KEY_LENGTH: usize = 32;
/// The length of the "key" portion of a Ristretto Schnorr secret key, in bytes.
const SECRET_KEY_KEY_LENGTH: usize = 32;
/// The length of the "nonce" portion of a Ristretto Schnorr secret key, in bytes.
const SECRET_KEY_NONCE_LENGTH: usize = 32;
/// The length of a Ristretto Schnorr key, `SecretKey`, in bytes.
pub const SECRET_KEY_LENGTH: usize = SECRET_KEY_KEY_LENGTH + SECRET_KEY_NONCE_LENGTH;
/// The length of an Ristretto Schnorr `Keypair`, in bytes.
pub const KEYPAIR_LENGTH: usize = SECRET_KEY_LENGTH + PUBLIC_KEY_LENGTH;
/// Methods for expanding a `MiniSecretKey` into a `SecretKey`.
///
/// Our `SecretKey`s consist of a scalar and nonce seed, both 32 bytes,
/// what EdDSA/Ed25519 calls an extended secret key. We normally create
/// `SecretKey`s by expanding a `MiniSecretKey`, what Esd25519 calls
/// a `SecretKey`. We provide two such methods, our suggested approach
/// produces uniformly distribted secret key scalars, but another
/// approach retains the bit clamping form Ed25519.
pub enum ExpansionMode {
/// Expand the `MiniSecretKey` into a uniformly distributed
/// `SecretKey`.
///
/// We preoduce the `SecretKey` using merlin and far more uniform
/// sampling, which might benefits some future protocols, and
/// might reduce binary size if used throughout.
///
/// We slightly prefer this method, but some existing code uses
/// `Ed25519` mode, so users cannot necessarily use this mode
/// if they require compatability with existing systems.
Uniform,
/// Expand this `MiniSecretKey` into a `SecretKey` using
/// ed25519-style bit clamping.
///
/// Ristretto points are represented by Ed25519 points internally
/// so concievably some future standard might expose a mapping
/// from Ristretto to Ed25519, which makes this mode useful.
/// At present, there is no such exposed mapping however because
/// two such mappings actually exist, depending upon the branch of
/// the inverse square root chosen by a Ristretto implementation.
/// There is however a concern that such a mapping would remain
/// a second class citizen, meaning implementations differ and
/// create incompatability.
///
/// We weakly recommend against emoloying this method. We include
/// it primarily because early Ristretto documentation touted the
/// relationship with Ed25519, which led to some deployments adopting
/// this expansion method.
Ed25519,
}
/// An EdDSA-like "secret" key seed.
///
/// These are seeds from which we produce a real `SecretKey`, which
/// EdDSA itself calls an extended secret key by hashing. We require
/// homomorphic properties unavailable from these seeds, so we renamed
/// these and reserve `SecretKey` for what EdDSA calls an extended
/// secret key.
#[derive(Clone,Zeroize)]
#[zeroize(drop)]
pub struct MiniSecretKey(pub (crate) [u8; MINI_SECRET_KEY_LENGTH]);
impl Debug for MiniSecretKey {
fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
write!(f, "MiniSecretKey: {:?}", &self.0[..])
}
}
impl Eq for MiniSecretKey {}
impl PartialEq for MiniSecretKey {
fn eq(&self, other: &Self) -> bool {
self.ct_eq(other).unwrap_u8() == 1u8
}
}
impl ConstantTimeEq for MiniSecretKey {
fn ct_eq(&self, other: &Self) -> Choice {
self.0.ct_eq(&other.0)
}
}
impl MiniSecretKey {
const DESCRIPTION : &'static str = "Analogous to ed25519 secret key as 32 bytes, see RFC8032.";
/// Avoids importing `ExpansionMode`
pub const UNIFORM_MODE : ExpansionMode = ExpansionMode::Uniform;
/// Avoids importing `ExpansionMode`
pub const ED25519_MODE : ExpansionMode = ExpansionMode::Ed25519;
/// Expand this `MiniSecretKey` into a `SecretKey`
///
/// We preoduce a secret keys using merlin and more uniformly
/// with this method, which reduces binary size and benefits
/// some future protocols.
///
/// # Examples
///
/// ```compile_fail
/// # fn main() {
/// use rand::{Rng, rngs::OsRng};
/// use schnorrkel::{MiniSecretKey, SecretKey};
///
/// let mini_secret_key: MiniSecretKey = MiniSecretKey::generate_with(OsRng);
/// let secret_key: SecretKey = mini_secret_key.expand_uniform();
/// # }
/// ```
fn expand_uniform(&self) -> SecretKey {
let mut t = merlin::Transcript::new(b"ExpandSecretKeys");
t.append_message(b"mini", &self.0[..]);
let mut scalar_bytes = [0u8; 64];
t.challenge_bytes(b"sk", &mut scalar_bytes);
let key = Scalar::from_bytes_mod_order_wide(&scalar_bytes);
let mut nonce = [0u8; 32];
t.challenge_bytes(b"no", &mut nonce);
SecretKey { key, nonce }
}
/// Expand this `MiniSecretKey` into a `SecretKey` using
/// ed25519-style bit clamping.
///
/// At present, there is no exposed mapping from Ristretto
/// to the underlying Edwards curve because Ristretto invovles
/// an inverse square root, and thus two such mappings exist.
/// Ristretto could be made usable with Ed25519 keys by choosing
/// one mapping as standard, but doing so makes the standard more
/// complex, and possibly harder to implement. If anyone does
/// standardize the mapping to the curve then this method permits
/// compatable schnorrkel and ed25519 keys.
///
/// # Examples
///
/// ```compile_fail
/// # fn main() {
/// use rand::{Rng, rngs::OsRng};
/// use schnorrkel::{MiniSecretKey, SecretKey};
///
/// let mini_secret_key: MiniSecretKey = MiniSecretKey::generate_with(OsRng);
/// let secret_key: SecretKey = mini_secret_key.expand_ed25519();
/// # }
/// ```
fn expand_ed25519(&self) -> SecretKey {
use sha2::{Sha512, digest::{Input,FixedOutput}};
let mut h = Sha512::default();
h.input(self.as_bytes());
let r = h.fixed_result();
// We need not clamp in a Schnorr group like Ristretto, but here
// we do so to improve Ed25519 comparability.
let mut key = [0u8; 32];
key.copy_from_slice(&r.as_slice()[0..32]);
key[0] &= 248;
key[31] &= 63;
key[31] |= 64;
// We then devide by the cofactor to internally keep a clean
// representation mod l.
scalars::divide_scalar_bytes_by_cofactor(&mut key);
let key = Scalar::from_bits(key);
let mut nonce = [0u8; 32];
nonce.copy_from_slice(&r.as_slice()[32..64]);
SecretKey{ key, nonce }
}
/// Derive the `SecretKey` corresponding to this `MiniSecretKey`.
///
/// We caution that `mode` must always be chosen consistently.
/// We slightly prefer `ExpansionMode::Uniform` here, but both
/// remain secure under almost all situations. There exists
/// deployed code using `ExpansionMode::Ed25519`, so you might
/// require that for compatability.
///
/// ```
/// # fn main() {
/// use rand::{Rng, rngs::OsRng};
/// use schnorrkel::{MiniSecretKey, SecretKey, ExpansionMode};
///
/// let mini_secret_key: MiniSecretKey = MiniSecretKey::generate_with(OsRng);
/// let secret_key: SecretKey = mini_secret_key.expand(ExpansionMode::Uniform);
/// # }
/// ```
pub fn expand(&self, mode: ExpansionMode) -> SecretKey {
match mode {
ExpansionMode::Uniform => self.expand_uniform(),
ExpansionMode::Ed25519 => self.expand_ed25519(),
}
}
/// Derive the `Keypair` corresponding to this `MiniSecretKey`.
pub fn expand_to_keypair(&self, mode: ExpansionMode) -> Keypair {
self.expand(mode).into()
}
/// Derive the `PublicKey` corresponding to this `MiniSecretKey`.
pub fn expand_to_public(&self, mode: ExpansionMode) -> PublicKey {
self.expand(mode).to_public()
}
/// Convert this secret key to a byte array.
#[inline]
pub fn to_bytes(&self) -> [u8; MINI_SECRET_KEY_LENGTH] {
self.0
}
/// View this secret key as a byte array.
#[inline]
pub fn as_bytes(&self) -> &[u8; MINI_SECRET_KEY_LENGTH] {
&self.0
}
/// Construct a `MiniSecretKey` from a slice of bytes.
///
/// # Example
///
/// ```
/// use schnorrkel::{MiniSecretKey, MINI_SECRET_KEY_LENGTH};
///
/// let secret_key_bytes: [u8; MINI_SECRET_KEY_LENGTH] = [
/// 157, 097, 177, 157, 239, 253, 090, 096,
/// 186, 132, 074, 244, 146, 236, 044, 196,
/// 068, 073, 197, 105, 123, 050, 105, 025,
/// 112, 059, 172, 003, 028, 174, 127, 096, ];
///
/// let secret_key: MiniSecretKey = MiniSecretKey::from_bytes(&secret_key_bytes).unwrap();
/// ```
///
/// # Returns
///
/// A `Result` whose okay value is an EdDSA `MiniSecretKey` or whose error value
/// is an `SignatureError` wrapping the internal error that occurred.
#[inline]
pub fn from_bytes(bytes: &[u8]) -> SignatureResult<MiniSecretKey> {
if bytes.len() != MINI_SECRET_KEY_LENGTH {
return Err(SignatureError::BytesLengthError {
name: "MiniSecretKey",
description: MiniSecretKey::DESCRIPTION,
length: MINI_SECRET_KEY_LENGTH
});
}
let mut bits: [u8; 32] = [0u8; 32];
bits.copy_from_slice(&bytes[..32]);
Ok(MiniSecretKey(bits))
}
/// Generate a `MiniSecretKey` from a `csprng`.
///
/// # Example
///
/// ```
/// use rand::{Rng, rngs::OsRng};
/// use schnorrkel::{PublicKey, MiniSecretKey, Signature};
///
/// let secret_key: MiniSecretKey = MiniSecretKey::generate_with(OsRng);
/// ```
///
/// # Input
///
/// A CSPRNG with a `fill_bytes()` method, e.g. `rand_chacha::ChaChaRng`
pub fn generate_with<R>(mut csprng: R) -> MiniSecretKey
where R: CryptoRng + RngCore,
{
let mut sk: MiniSecretKey = MiniSecretKey([0u8; 32]);
csprng.fill_bytes(&mut sk.0);
sk
}
/// Generate a `MiniSecretKey` from rand's `thread_rng`.
///
/// # Example
///
/// ```
/// use schnorrkel::{PublicKey, MiniSecretKey, Signature};
///
/// let secret_key: MiniSecretKey = MiniSecretKey::generate();
/// ```
///
/// Afterwards, you can generate the corresponding public key.
///
/// ```
/// # use rand::{Rng, SeedableRng};
/// # use rand_chacha::ChaChaRng;
/// # use schnorrkel::{PublicKey, MiniSecretKey, ExpansionMode, Signature};
/// #
/// # let mut csprng: ChaChaRng = ChaChaRng::from_seed([0u8; 32]);
/// # let secret_key: MiniSecretKey = MiniSecretKey::generate_with(&mut csprng);
///
/// let public_key: PublicKey = secret_key.expand_to_public(ExpansionMode::Ed25519);
/// ```
#[cfg(feature = "getrandom")]
pub fn generate() -> MiniSecretKey {
Self::generate_with(super::rand_hack())
}
}
serde_boilerplate!(MiniSecretKey);
/// A seceret key for use with Ristretto Schnorr signatures.
///
/// Internally, these consist of a scalar mod l along with a seed for
/// nonce generation. In this way, we ensure all scalar arithmatic
/// works smoothly in operations like threshold or multi-signatures,
/// or hierarchical deterministic key derivations.
///
/// We keep our secret key serializaion "almost" compatable with EdDSA
/// "expanded" secret key serializaion by multiplying the scalar by the
/// cofactor 8, as integers, and dividing on deserializaion.
/// We do not however attempt to keep the scalar's high bit set, especially
/// not during hierarchical deterministic key derivations, so some Ed25519
/// libraries might compute the public key incorrectly from our secret key.
#[derive(Clone,Zeroize)]
#[zeroize(drop)]
pub struct SecretKey {
/// Actual public key represented as a scalar.
pub (crate) key: Scalar,
/// Seed for deriving the nonces used in signing.
///
/// We require this be random and secret or else key compromise attacks will ensue.
/// Any modificaiton here may dirupt some non-public key derivation techniques.
pub (crate) nonce: [u8; 32],
}
impl Debug for SecretKey {
fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
write!(f, "SecretKey {{ key: {:?} nonce: {:?} }}", &self.key, &self.nonce)
}
}
impl Eq for SecretKey {}
impl PartialEq for SecretKey {
fn eq(&self, other: &Self) -> bool {
self.ct_eq(other).unwrap_u8() == 1u8
}
}
impl ConstantTimeEq for SecretKey {
fn ct_eq(&self, other: &Self) -> Choice {
self.key.ct_eq(&other.key)
}
}
/*
impl From<&MiniSecretKey> for SecretKey {
/// Construct an `SecretKey` from a `MiniSecretKey`.
///
/// # Examples
///
/// ```
/// # fn main() {
/// use rand::{Rng, rngs::OsRng};
/// use schnorrkel::{MiniSecretKey, SecretKey};
///
/// let mini_secret_key: MiniSecretKey = MiniSecretKey::generate_with(OsRng);
/// let secret_key: SecretKey = SecretKey::from(&mini_secret_key);
/// # }
/// ```
fn from(msk: &MiniSecretKey) -> SecretKey {
msk.expand(ExpansionMode::Ed25519)
}
}
*/
impl SecretKey {
const DESCRIPTION : &'static str = "An ed25519-like expanded secret key as 64 bytes, as specified in RFC8032.";
/// Convert this `SecretKey` into an array of 64 bytes with.
///
/// Returns an array of 64 bytes, with the first 32 bytes being
/// the secret scalar represented cannonically, and the last
/// 32 bytes being the seed for nonces.
///
/// # Examples
///
/// ```
/// use schnorrkel::{MiniSecretKey, SecretKey};
///
/// let mini_secret_key: MiniSecretKey = MiniSecretKey::generate();
/// let secret_key: SecretKey = mini_secret_key.expand(MiniSecretKey::UNIFORM_MODE);
/// # // was SecretKey::from(&mini_secret_key);
/// let secret_key_bytes: [u8; 64] = secret_key.to_bytes();
/// let bytes: [u8; 64] = secret_key.to_bytes();
/// let secret_key_again: SecretKey = SecretKey::from_bytes(&bytes[..]).unwrap();
/// assert_eq!(&bytes[..], & secret_key_again.to_bytes()[..]);
/// ```
#[inline]
pub fn to_bytes(&self) -> [u8; SECRET_KEY_LENGTH] {
let mut bytes: [u8; 64] = [0u8; 64];
bytes[..32].copy_from_slice(&self.key.to_bytes()[..]);
bytes[32..].copy_from_slice(&self.nonce[..]);
bytes
}
/// Construct an `SecretKey` from a slice of bytes.
///
/// # Examples
///
/// ```
/// use schnorrkel::{MiniSecretKey, SecretKey, ExpansionMode, SignatureError};
///
/// let mini_secret_key: MiniSecretKey = MiniSecretKey::generate();
/// let secret_key: SecretKey = mini_secret_key.expand(MiniSecretKey::ED25519_MODE);
/// # // was SecretKey::from(&mini_secret_key);
/// let bytes: [u8; 64] = secret_key.to_bytes();
/// let secret_key_again: SecretKey = SecretKey::from_bytes(&bytes[..]).unwrap();
/// assert_eq!(secret_key_again, secret_key);
/// ```
#[inline]
pub fn from_bytes(bytes: &[u8]) -> SignatureResult<SecretKey> {
if bytes.len() != SECRET_KEY_LENGTH {
return Err(SignatureError::BytesLengthError{
name: "SecretKey",
description: SecretKey::DESCRIPTION,
length: SECRET_KEY_LENGTH,
});
}
let mut key: [u8; 32] = [0u8; 32];
key.copy_from_slice(&bytes[00..32]);
let key = Scalar::from_canonical_bytes(key).ok_or(SignatureError::ScalarFormatError) ?;
let mut nonce: [u8; 32] = [0u8; 32];
nonce.copy_from_slice(&bytes[32..64]);
Ok(SecretKey{ key, nonce })
}
/// Convert this `SecretKey` into an array of 64 bytes, corresponding to
/// an Ed25519 expanded secret key.
///
/// Returns an array of 64 bytes, with the first 32 bytes being
/// the secret scalar shifted ed25519 style, and the last 32 bytes
/// being the seed for nonces.
#[inline]
pub fn to_ed25519_bytes(&self) -> [u8; SECRET_KEY_LENGTH] {
let mut bytes: [u8; 64] = [0u8; 64];
let mut key = self.key.to_bytes();
// We multiply by the cofactor to improve ed25519 compatability,
// while our internally using a scalar mod l.
scalars::multiply_scalar_bytes_by_cofactor(&mut key);
bytes[..32].copy_from_slice(&key[..]);
bytes[32..].copy_from_slice(&self.nonce[..]);
bytes
}
/// Convert this `SecretKey` into an Ed25519 expanded secreyt key.
#[cfg(feature = "ed25519_dalek")]
pub fn to_ed25519_expanded_secret_key(&self) -> ::ed25519_dalek::ExpandedSecretKey {
::ed25519_dalek::ExpandedSecretKey::from_bytes(&self.to_ed25519_bytes()[..])
.expect("Improper serialisation of Ed25519 secret key!")
}
/// Construct an `SecretKey` from a slice of bytes, corresponding to
/// an Ed25519 expanded secret key.
///
/// # Example
///
/// ```
/// use schnorrkel::{SecretKey, SECRET_KEY_LENGTH};
/// use hex_literal::hex;
///
/// let secret = hex!("28b0ae221c6bb06856b287f60d7ea0d98552ea5a16db16956849aa371db3eb51fd190cce74df356432b410bd64682309d6dedb27c76845daf388557cbac3ca34");
/// let public = hex!("46ebddef8cd9bb167dc30878d7113b7e168e6f0646beffd77d69d39bad76b47a");
/// let secret_key = SecretKey::from_ed25519_bytes(&secret[..]).unwrap();
/// assert_eq!(secret_key.to_public().to_bytes(), public);
/// ```
#[inline]
pub fn from_ed25519_bytes(bytes: &[u8]) -> SignatureResult<SecretKey> {
if bytes.len() != SECRET_KEY_LENGTH {
return Err(SignatureError::BytesLengthError{
name: "SecretKey",
description: SecretKey::DESCRIPTION,
length: SECRET_KEY_LENGTH,
});
}
let mut key: [u8; 32] = [0u8; 32];
key.copy_from_slice(&bytes[00..32]);
// TODO: We should consider making sure the scalar is valid,
// maybe by zering the high bit, or preferably by checking < l.
// key[31] &= 0b0111_1111;
// We devide by the cofactor to internally keep a clean
// representation mod l.
scalars::divide_scalar_bytes_by_cofactor(&mut key);
let key = Scalar::from_bits(key);
let mut nonce: [u8; 32] = [0u8; 32];
nonce.copy_from_slice(&bytes[32..64]);
Ok(SecretKey{ key, nonce })
}
/// Generate an "unbiased" `SecretKey` directly from a user
/// suplied `csprng` uniformly, bypassing the `MiniSecretKey`
/// layer.
pub fn generate_with<R>(mut csprng: R) -> SecretKey
where R: CryptoRng + RngCore,
{
let mut key: [u8; 64] = [0u8; 64];
csprng.fill_bytes(&mut key);
let mut nonce: [u8; 32] = [0u8; 32];
csprng.fill_bytes(&mut nonce);
SecretKey { key: Scalar::from_bytes_mod_order_wide(&key), nonce }
}
/// Generate an "unbiased" `SecretKey` directly,
/// bypassing the `MiniSecretKey` layer.
#[cfg(feature = "getrandom")]
pub fn generate() -> SecretKey {
Self::generate_with(super::rand_hack())
}
/// Derive the `PublicKey` corresponding to this `SecretKey`.
pub fn to_public(&self) -> PublicKey {
// No clamping in a Schnorr group
PublicKey::from_point(&self.key * &constants::RISTRETTO_BASEPOINT_TABLE)
}
/// Derive the `PublicKey` corresponding to this `SecretKey`.
pub fn to_keypair(self) -> Keypair {
let public = self.to_public();
Keypair { secret: self, public }
}
}
serde_boilerplate!(SecretKey);
/// A Ristretto Schnorr public key.
///
/// Internally, these are represented as a `RistrettoPoint`, meaning
/// an Edwards point with a static guarantee to be 2-torsion free.
///
/// At present, we decompress `PublicKey`s into this representation
/// during deserialization, which improves error handling, but costs
/// a compression during signing and verifiaction.
#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct PublicKey(pub (crate) RistrettoBoth);
impl Debug for PublicKey {
fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
write!(f, "PublicKey( {:?} )", self.0)
}
}
/*
impl Zeroize for PublicKey {
fn zeroize(&mut self) {
self.0.zeroize()
}
}
*/
// We should imho drop this impl but it benifits users who start with ring.
impl AsRef<[u8]> for PublicKey {
fn as_ref(&self) -> &[u8] {
self.as_compressed().as_bytes()
}
}
impl PublicKey {
const DESCRIPTION : &'static str = "A Ristretto Schnorr public key represented as a 32-byte Ristretto compressed point";
/// Access the compressed Ristretto form
pub fn as_compressed(&self) -> &CompressedRistretto { &self.0.as_compressed() }
/// Extract the compressed Ristretto form
pub fn into_compressed(self) -> CompressedRistretto { self.0.into_compressed() }
/// Access the point form
pub fn as_point(&self) -> &RistrettoPoint { &self.0.as_point() }
/// Extract the point form
pub fn into_point(self) -> RistrettoPoint { self.0.into_point() }
/// Decompress into the `PublicKey` format that also retains the
/// compressed form.
pub fn from_compressed(compressed: CompressedRistretto) -> SignatureResult<PublicKey> {
Ok(PublicKey(RistrettoBoth::from_compressed(compressed) ?))
}
/// Compress into the `PublicKey` format that also retains the
/// uncompressed form.
pub fn from_point(point: RistrettoPoint) -> PublicKey {
PublicKey(RistrettoBoth::from_point(point))
}
/// Convert this public key to a byte array.
/// # Example
///
/// ```
/// use schnorrkel::{SecretKey, PublicKey, PUBLIC_KEY_LENGTH, SignatureError};
///
/// let public_key: PublicKey = SecretKey::generate().to_public();
/// let public_key_bytes = public_key.to_bytes();
/// let public_key_again: PublicKey = PublicKey::from_bytes(&public_key_bytes[..]).unwrap();
/// assert_eq!(public_key_bytes, public_key_again.to_bytes());
/// ```
#[inline]
pub fn to_bytes(&self) -> [u8; PUBLIC_KEY_LENGTH] {
self.as_compressed().to_bytes()
}
/// Construct a `PublicKey` from a slice of bytes.
///
/// # Example
///
/// ```
/// use schnorrkel::{PublicKey, PUBLIC_KEY_LENGTH, SignatureError};
///
/// let public_key_bytes: [u8; PUBLIC_KEY_LENGTH] = [
/// 208, 120, 140, 129, 177, 179, 237, 159,
/// 252, 160, 028, 013, 206, 005, 211, 241,
/// 192, 218, 001, 097, 130, 241, 020, 169,
/// 119, 046, 246, 029, 079, 080, 077, 084];
///
/// let public_key = PublicKey::from_bytes(&public_key_bytes).unwrap();
/// assert_eq!(public_key.to_bytes(), public_key_bytes);
/// ```
///
/// # Returns
///
/// A `Result` whose okay value is an EdDSA `PublicKey` or whose error value
/// is an `SignatureError` describing the error that occurred.
#[inline]
pub fn from_bytes(bytes: &[u8]) -> SignatureResult<PublicKey> {
Ok(PublicKey(RistrettoBoth::from_bytes_ser("PublicKey",PublicKey::DESCRIPTION,bytes) ?))
}
}
impl From<SecretKey> for PublicKey {
fn from(source: SecretKey) -> PublicKey {
source.to_public()
}
}
serde_boilerplate!(PublicKey);
/// A Ristretto Schnorr keypair.
#[derive(Clone,Debug)]
// #[derive(Clone,Zeroize)]
// #[zeroize(drop)]
pub struct Keypair {
/// The secret half of this keypair.
pub secret: SecretKey,
/// The public half of this keypair.
pub public: PublicKey,
}
impl Zeroize for Keypair {
fn zeroize(&mut self) {
self.secret.zeroize();
}
}
impl Drop for Keypair {
fn drop(&mut self) {
self.zeroize();
}
}
impl From<SecretKey> for Keypair {
fn from(secret: SecretKey) -> Keypair {
let public = secret.to_public();
Keypair{ secret, public }
}
}
impl Keypair {
const DESCRIPTION : &'static str = "A 96 bytes Ristretto Schnorr keypair";
/*
const DESCRIPTION_LONG : &'static str =
"An ristretto schnorr keypair, 96 bytes in total, where the \
first 64 bytes contains the secret key represented as an \
ed25519 expanded secret key, as specified in RFC8032, and \
the subsequent 32 bytes gives the public key as a compressed \
ristretto point.";
*/
/// Serialize `Keypair` to bytes.
///
/// # Returns
///
/// A byte array `[u8; KEYPAIR_LENGTH]` consisting of first a
/// `SecretKey` serialized cannonically, and next the Ristterro
/// `PublicKey`
///
/// # Examples
///
/// ```
/// use schnorrkel::{Keypair, KEYPAIR_LENGTH};
///
/// let keypair: Keypair = Keypair::generate();
/// let bytes: [u8; KEYPAIR_LENGTH] = keypair.to_bytes();
/// let keypair_too = Keypair::from_bytes(&bytes[..]).unwrap();
/// assert_eq!(&bytes[..], & keypair_too.to_bytes()[..]);
/// ```
pub fn to_bytes(&self) -> [u8; KEYPAIR_LENGTH] {
let mut bytes: [u8; KEYPAIR_LENGTH] = [0u8; KEYPAIR_LENGTH];
bytes[..SECRET_KEY_LENGTH].copy_from_slice(& self.secret.to_bytes());
bytes[SECRET_KEY_LENGTH..].copy_from_slice(& self.public.to_bytes());
bytes
}
/// Deserialize a `Keypair` from bytes.
///
/// # Inputs
///
/// * `bytes`: an `&[u8]` consisting of byte representations of
/// first a `SecretKey` and then the corresponding ristretto
/// `PublicKey`.
///
/// # Examples
///
/// ```
/// use schnorrkel::{Keypair, KEYPAIR_LENGTH};
/// use hex_literal::hex;
///
/// // TODO: Fix test vector
/// // let keypair_bytes = hex!("28b0ae221c6bb06856b287f60d7ea0d98552ea5a16db16956849aa371db3eb51fd190cce74df356432b410bd64682309d6dedb27c76845daf388557cbac3ca3446ebddef8cd9bb167dc30878d7113b7e168e6f0646beffd77d69d39bad76b47a");
/// // let keypair: Keypair = Keypair::from_bytes(&keypair_bytes[..]).unwrap();
/// // assert_eq!(&keypair_bytes[..], & keypair.to_bytes()[..]);
/// ```
///
/// # Returns
///
/// A `Result` whose okay value is an EdDSA `Keypair` or whose error value
/// is an `SignatureError` describing the error that occurred.
pub fn from_bytes(bytes: &[u8]) -> SignatureResult<Keypair> {
if bytes.len() != KEYPAIR_LENGTH {
return Err(SignatureError::BytesLengthError {
name: "Keypair",
description: Keypair::DESCRIPTION,
length: KEYPAIR_LENGTH
});
}
let secret = SecretKey::from_bytes(&bytes[..SECRET_KEY_LENGTH]) ?;
let public = PublicKey::from_bytes(&bytes[SECRET_KEY_LENGTH..]) ?;
Ok(Keypair{ secret: secret, public: public })
}
/// Serialize `Keypair` to bytes with Ed25519 secret key format.
///
/// # Returns
///
/// A byte array `[u8; KEYPAIR_LENGTH]` consisting of first a
/// `SecretKey` serialized like Ed25519, and next the Ristterro
/// `PublicKey`
///
///
pub fn to_half_ed25519_bytes(&self) -> [u8; KEYPAIR_LENGTH] {
let mut bytes: [u8; KEYPAIR_LENGTH] = [0u8; KEYPAIR_LENGTH];
bytes[..SECRET_KEY_LENGTH].copy_from_slice(& self.secret.to_ed25519_bytes());
bytes[SECRET_KEY_LENGTH..].copy_from_slice(& self.public.to_bytes());
bytes
}
/// Deserialize a `Keypair` from bytes with Ed25519 style `SecretKey` format.
///
/// # Inputs
///
/// * `bytes`: an `&[u8]` representing the scalar for the secret key, and a
/// compressed Ristretto point, both as bytes.
///
/// # Examples
///
/// ```
/// use schnorrkel::{Keypair, KEYPAIR_LENGTH};
/// use hex_literal::hex;
///
/// let keypair_bytes = hex!("28b0ae221c6bb06856b287f60d7ea0d98552ea5a16db16956849aa371db3eb51fd190cce74df356432b410bd64682309d6dedb27c76845daf388557cbac3ca3446ebddef8cd9bb167dc30878d7113b7e168e6f0646beffd77d69d39bad76b47a");
/// let keypair: Keypair = Keypair::from_half_ed25519_bytes(&keypair_bytes[..]).unwrap();
/// assert_eq!(&keypair_bytes[..], & keypair.to_half_ed25519_bytes()[..]);
/// ```
///
/// # Returns
///
/// A `Result` whose okay value is an EdDSA `Keypair` or whose error value
/// is an `SignatureError` describing the error that occurred.
pub fn from_half_ed25519_bytes(bytes: &[u8]) -> SignatureResult<Keypair> {
if bytes.len() != KEYPAIR_LENGTH {
return Err(SignatureError::BytesLengthError {
name: "Keypair",
description: Keypair::DESCRIPTION,
length: KEYPAIR_LENGTH
});
}
let secret = SecretKey::from_ed25519_bytes(&bytes[..SECRET_KEY_LENGTH]) ?;
let public = PublicKey::from_bytes(&bytes[SECRET_KEY_LENGTH..]) ?;
Ok(Keypair{ secret: secret, public: public })
}
/// Generate a Ristretto Schnorr `Keypair` directly,
/// bypassing the `MiniSecretKey` layer.
///
/// # Example
///
/// ```
/// # fn main() {
///
/// use rand::{Rng, rngs::OsRng};
/// use schnorrkel::Keypair;
/// use schnorrkel::Signature;
///
/// let keypair: Keypair = Keypair::generate_with(OsRng);
///
/// # }
/// ```
///
/// # Input
///
/// A CSPRNG with a `fill_bytes()` method, e.g. `rand_chacha::ChaChaRng`.
///
/// We generate a `SecretKey` directly bypassing `MiniSecretKey`,
/// so our secret keys do not satisfy the high bit "clamping"
/// impoised on Ed25519 keys.
pub fn generate_with<R>(csprng: R) -> Keypair
where R: CryptoRng + RngCore,
{
let secret: SecretKey = SecretKey::generate_with(csprng);
let public: PublicKey = secret.to_public();
Keypair{ public, secret }
}
/// Generate a Ristretto Schnorr `Keypair` directly, from a user
/// suplied `csprng`, bypassing the `MiniSecretKey` layer.
#[cfg(feature = "getrandom")]
pub fn generate() -> Keypair {
Self::generate_with(super::rand_hack())
}
}
serde_boilerplate!(Keypair);
#[cfg(test)]
mod test {
// use std::vec::Vec;
use super::*;
/*
TODO: Use some Ristretto point to do this test correctly.
use curve25519_dalek::edwards::{CompressedEdwardsY}; // EdwardsPoint
#[test]
fn public_key_from_bytes() {
static ED25519_PUBLIC_KEY : CompressedEdwardsY = CompressedEdwardsY([
215, 090, 152, 001, 130, 177, 010, 183,
213, 075, 254, 211, 201, 100, 007, 058,
014, 225, 114, 243, 218, 166, 035, 037,
175, 002, 026, 104, 247, 007, 081, 026, ]);
let pk = ED25519_PUBLIC_KEY.decompress().unwrap();
// let pk = unsafe { ::std::mem::transmute::<EdwardsPoint,RistrettoPoint>(pk) };
let point = super::super::ed25519::edwards_to_ristretto(pk).unwrap();
let ristretto_public_key = PublicKey::from_point(point);
assert_eq!(
ristretto_public_key.to_ed25519_public_key_bytes(),
pk.mul_by_cofactor().compress().0
);
// Make another function so that we can test the ? operator.
fn do_the_test(s: &[u8]) -> Result<PublicKey, SignatureError> {
let public_key = PublicKey::from_bytes(s) ?;
Ok(public_key)
}
assert_eq!(
do_the_test(ristretto_public_key.as_ref()),
Ok(ristretto_public_key)
);
assert_eq!(
do_the_test(&ED25519_PUBLIC_KEY.0), // Not a Ristretto public key
Err(SignatureError::PointDecompressionError)
);
}
*/
#[test]
fn derives_from_core() {
let pk_d = PublicKey::default();
debug_assert_eq!(
pk_d.as_point().compress(),
CompressedRistretto::default()
);
debug_assert_eq!(
pk_d.as_compressed().decompress().unwrap(),
RistrettoPoint::default()
);
}
#[test]
fn keypair_zeroize() {
// #[cfg(feature = "getrandom")]
let mut csprng = ::rand_core::OsRng;
let mut keypair = Keypair::generate_with(&mut csprng);
keypair.zeroize();
fn as_bytes<T>(x: &T) -> &[u8] {
use core::mem;
use core::slice;
unsafe {
slice::from_raw_parts(x as *const T as *const u8, mem::size_of_val(x))
}
}
assert!(!as_bytes(&keypair).iter().all(|x| *x == 0u8));
}
#[test]
fn pubkey_from_mini_secret_and_expanded_secret() {
// #[cfg(feature = "getrandom")]
let mut csprng = ::rand_core::OsRng;
let mini_secret: MiniSecretKey = MiniSecretKey::generate_with(&mut csprng);
let secret: SecretKey = mini_secret.expand(ExpansionMode::Ed25519);
let public_from_mini_secret: PublicKey = mini_secret.expand_to_public(ExpansionMode::Ed25519);
let public_from_secret: PublicKey = secret.to_public();
assert!(public_from_mini_secret == public_from_secret);
let secret: SecretKey = mini_secret.expand(ExpansionMode::Uniform);
let public_from_mini_secret: PublicKey = mini_secret.expand_to_public(ExpansionMode::Uniform);
let public_from_secret: PublicKey = secret.to_public();
assert!(public_from_mini_secret == public_from_secret);
}
}