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use std::marker::PhantomData;
use derive_builder::Builder;
use serde::{Deserialize, Serialize};
use sha2::{Digest, Sha256};
#[derive(Serialize, Builder, Deserialize, PartialEq, Clone, Debug)]
pub struct PoW<T> {
pub nonce: u64,
pub result: String,
#[builder(default = "PhantomData", setter(skip))]
_spook: PhantomData<T>,
}
#[derive(Serialize, Deserialize, Builder, PartialEq, Clone, Debug)]
pub struct Config {
pub salt: String,
}
impl Config {
pub fn prove_work<T>(&self, t: &T, difficulty: u128) -> bincode::Result<PoW<T>>
where
T: Serialize,
{
bincode::serialize(t).map(|v| self.prove_work_serialized(&v, difficulty))
}
pub fn prove_work_serialized<T>(&self, prefix: &[u8], difficulty: u128) -> PoW<T>
where
T: Serialize,
{
let prefix_sha = Sha256::new().chain(&self.salt).chain(prefix);
let mut n = 0;
let mut result = 0;
while result < difficulty {
n += 1;
result = score(prefix_sha.clone(), n);
}
PoW {
nonce: n,
result: result.to_string(),
_spook: PhantomData,
}
}
pub fn calculate<T>(&self, pow: &PoW<T>, t: &T) -> bincode::Result<u128>
where
T: Serialize,
{
bincode::serialize(t).map(|v| self.calculate_serialized(pow, &v))
}
pub fn calculate_serialized<T>(&self, pow: &PoW<T>, target: &[u8]) -> u128
where
T: Serialize,
{
score(Sha256::new().chain(&self.salt).chain(target), pow.nonce)
}
pub fn is_valid_proof<T>(&self, pow: &PoW<T>, t: &T) -> bool
where
T: Serialize,
{
match self.calculate(pow, t) {
Ok(res) => {
return if pow.result == res.to_string() {
true
} else {
false
}
}
Err(_) => return false,
}
}
pub fn is_sufficient_difficulty<T>(&self, pow: &PoW<T>, target_diff: u128) -> bool
where
T: Serialize,
{
match pow.result.parse::<u128>() {
Ok(res) => return res >= target_diff,
Err(_) => return false,
}
}
}
fn score(prefix_sha: Sha256, nonce: u64) -> u128 {
first_bytes_as_u128(
prefix_sha
.chain(&nonce.to_be_bytes())
.finalize()
.as_slice(),
)
}
fn first_bytes_as_u128(inp: &[u8]) -> u128 {
bincode::deserialize(&inp).unwrap()
}
#[cfg(test)]
mod test {
use super::*;
const DIFFICULTY: u128 = 0xff000000000000000000000000000000;
fn get_config() -> Config {
ConfigBuilder::default()
.salt(
"79ziepia7vhjgviiwjhnend3ofjqocsi2winc4ptqhmkvcajihywxcizewvckg9h6gs4j83v9".into(),
)
.build()
.unwrap()
}
#[test]
fn base_functionality() {
let phrase = b"Ex nihilo nihil fit.".to_vec();
let config = get_config();
let pw = config.prove_work(&phrase, DIFFICULTY).unwrap();
assert!(config.calculate(&pw, &phrase).unwrap() >= DIFFICULTY);
assert!(config.is_valid_proof(&pw, &phrase));
assert!(config.is_sufficient_difficulty(&pw, DIFFICULTY));
}
#[test]
fn double_pow() {
let phrase = "Ex nihilo nihil fit.".to_owned();
let config = get_config();
let pw = config.prove_work(&phrase, DIFFICULTY).unwrap();
let pwpw = config.prove_work(&pw, DIFFICULTY).unwrap();
assert!(config.calculate(&pw, &phrase).unwrap() >= DIFFICULTY);
assert!(config.is_valid_proof(&pw, &phrase));
assert!(config.is_sufficient_difficulty(&pw, DIFFICULTY));
assert!(config.calculate(&pwpw, &pw).unwrap() >= DIFFICULTY);
assert!(config.is_valid_proof(&pwpw, &pw));
assert!(config.is_sufficient_difficulty(&pwpw, DIFFICULTY));
}
#[test]
fn is_not_valid_proof() {
let phrase = "Ex nihilo nihil fit.".to_owned();
let phrase2 = "Omne quod movetur ab alio movetur.".to_owned();
let config = get_config();
let pw = config.prove_work(&phrase, DIFFICULTY).unwrap();
let pw2 = config.prove_work(&phrase2, DIFFICULTY).unwrap();
assert!(!config.is_valid_proof(&pw, &phrase2));
assert!(!config.is_valid_proof(&pw2, &phrase));
}
#[test]
fn serialization_test() {
let target: u8 = 1;
let config = get_config();
let pw = config.prove_work(&target, DIFFICULTY).unwrap();
let message: (u8, PoW<u8>) = (target, pw);
let message_ser = bincode::serialize(&message).unwrap();
let recieved_message: (u8, PoW<u8>) = bincode::deserialize(&message_ser).unwrap();
assert_eq!(recieved_message, message);
assert!(config.is_sufficient_difficulty(&message.1, DIFFICULTY));
assert!(config.is_valid_proof(&message.1, &target));
}
}