115 lines
3.2 KiB
Rust
115 lines
3.2 KiB
Rust
//! Equihash Solution and related items.
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use std::{fmt, io};
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use serde_big_array::BigArray;
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use crate::{
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block::Header,
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serialization::{
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zcash_serialize_bytes, SerializationError, ZcashDeserialize, ZcashDeserializeInto,
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ZcashSerialize,
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},
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};
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/// The error type for Equihash
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#[non_exhaustive]
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#[derive(Debug, thiserror::Error)]
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#[error("invalid equihash solution for BlockHeader")]
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pub struct Error(#[from] equihash::Error);
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/// The size of an Equihash solution in bytes (always 1344).
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pub(crate) const SOLUTION_SIZE: usize = 1344;
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/// Equihash Solution.
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///
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/// A wrapper around [u8; 1344] because Rust doesn't implement common
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/// traits like `Debug`, `Clone`, etc for collections like array
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/// beyond lengths 0 to 32.
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///
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/// The size of an Equihash solution in bytes is always 1344 so the
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/// length of this type is fixed.
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#[derive(Deserialize, Serialize)]
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pub struct Solution(#[serde(with = "BigArray")] pub [u8; SOLUTION_SIZE]);
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impl Solution {
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/// The length of the portion of the header used as input when verifying
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/// equihash solutions, in bytes.
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///
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/// Excludes the 32-byte nonce, which is passed as a separate argument
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/// to the verification function.
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pub const INPUT_LENGTH: usize = 4 + 32 * 3 + 4 * 2;
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/// Returns `Ok(())` if `EquihashSolution` is valid for `header`
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#[allow(clippy::unwrap_in_result)]
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pub fn check(&self, header: &Header) -> Result<(), Error> {
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let n = 200;
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let k = 9;
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let nonce = &header.nonce;
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let solution = &self.0;
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let mut input = Vec::new();
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header
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.zcash_serialize(&mut input)
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.expect("serialization into a vec can't fail");
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let input = &input[0..Solution::INPUT_LENGTH];
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equihash::is_valid_solution(n, k, input, nonce, solution)?;
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Ok(())
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}
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}
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impl PartialEq<Solution> for Solution {
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fn eq(&self, other: &Solution) -> bool {
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self.0.as_ref() == other.0.as_ref()
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}
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}
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impl fmt::Debug for Solution {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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f.debug_tuple("EquihashSolution")
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.field(&hex::encode(&self.0[..]))
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.finish()
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}
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}
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// These impls all only exist because of array length restrictions.
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impl Copy for Solution {}
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impl Clone for Solution {
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fn clone(&self) -> Self {
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let mut bytes = [0; SOLUTION_SIZE];
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bytes[..].copy_from_slice(&self.0[..]);
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Self(bytes)
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}
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}
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impl Eq for Solution {}
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impl ZcashSerialize for Solution {
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fn zcash_serialize<W: io::Write>(&self, writer: W) -> Result<(), io::Error> {
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zcash_serialize_bytes(&self.0.to_vec(), writer)
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}
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}
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impl ZcashDeserialize for Solution {
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fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
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let solution: Vec<u8> = (&mut reader).zcash_deserialize_into()?;
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if solution.len() != SOLUTION_SIZE {
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return Err(SerializationError::Parse(
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"incorrect equihash solution size",
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));
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}
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let mut bytes = [0; SOLUTION_SIZE];
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// Won't panic, because we just checked the length.
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bytes.copy_from_slice(&solution);
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Ok(Self(bytes))
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}
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}
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