93 lines
2.9 KiB
Rust
93 lines
2.9 KiB
Rust
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use std::convert::TryFrom;
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use curve25519_dalek::edwards::EdwardsPoint;
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use crate::{Error, Signature};
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/// A refinement type for `[u8; 32]` indicating that the bytes represent
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/// an encoding of an Ed25519 public key.
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///
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/// This is useful for representing a compressed public key; the
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/// [`PublicKey`] type in this library holds other decompressed state
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/// used in signature verification.
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#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
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#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
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pub struct PublicKeyBytes(pub(crate) [u8; 32]);
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impl From<[u8; 32]> for PublicKeyBytes {
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fn from(bytes: [u8; 32]) -> PublicKeyBytes {
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PublicKeyBytes(bytes)
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}
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}
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impl From<PublicKeyBytes> for [u8; 32] {
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fn from(refined: PublicKeyBytes) -> [u8; 32] {
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refined.0
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}
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}
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/// A valid Ed25519 public key.
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///
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/// This type holds decompressed state used in signature verification; if the
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/// public key may not be used immediately, it is probably better to use
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/// [`PublicKeyBytes`], which is a refinement type for `[u8; 32]`.
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///
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/// ## Consensus properties
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///
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/// Valid Ed25519 public keys are defined in
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/// [§5.4.5](https://zips.z.cash/protocol/protocol.pdf#concretejssig) of the
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/// Zcash protocol specification.
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///
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/// FIXME: the spec says that a public key must be a point of order `l`; is
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/// this exactly what is meant? Would a public key of order `8*l` be rejected
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/// by the implementation? Or is this intended to specify that the point must
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/// not be of *small* order?
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#[derive(Copy, Clone, Debug)]
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#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
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#[cfg_attr(feature = "serde", serde(try_from = "PublicKeyBytes"))]
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#[cfg_attr(feature = "serde", serde(into = "PublicKeyBytes"))]
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pub struct PublicKey {
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pub(crate) bytes: PublicKeyBytes,
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pub(crate) point: EdwardsPoint,
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}
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impl From<PublicKey> for PublicKeyBytes {
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fn from(pk: PublicKey) -> PublicKeyBytes {
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pk.bytes
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}
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}
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impl From<PublicKey> for [u8; 32] {
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fn from(pk: PublicKey) -> [u8; 32] {
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pk.bytes.0
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}
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}
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impl TryFrom<PublicKeyBytes> for PublicKey {
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type Error = Error;
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fn try_from(bytes: PublicKeyBytes) -> Result<Self, Self::Error> {
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use curve25519_dalek::edwards::CompressedEdwardsY;
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// XXX check consensus rules, see FIXME above
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let point = CompressedEdwardsY(bytes.0)
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.decompress()
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.ok_or(Error::MalformedPublicKey)?;
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Ok(PublicKey { point, bytes })
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}
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}
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impl TryFrom<[u8; 32]> for PublicKey {
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type Error = Error;
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fn try_from(bytes: [u8; 32]) -> Result<Self, Self::Error> {
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use std::convert::TryInto;
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PublicKeyBytes::from(bytes).try_into()
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}
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}
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impl PublicKey {
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/// Verify a purported `signature` on the given `msg`.
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pub fn verify(&self, _signature: &Signature, _msg: &[u8]) -> Result<(), Error> {
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unimplemented!();
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}
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}
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