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#![doc(
html_logo_url = "https://raw.githubusercontent.com/maidsafe/QA/master/Images/maidsafe_logo.png",
html_favicon_url = "https://maidsafe.net/img/favicon.ico",
test(attr(forbid(warnings)))
)]
#![forbid(
bad_style,
arithmetic_overflow,
mutable_transmutes,
no_mangle_const_items,
unknown_crate_types
)]
#![deny(
deprecated,
improper_ctypes,
missing_docs,
non_shorthand_field_patterns,
overflowing_literals,
stable_features,
unconditional_recursion,
unknown_lints,
unsafe_code,
unused,
unused_allocation,
unused_attributes,
unused_comparisons,
unused_features,
unused_parens,
while_true,
warnings
)]
#![warn(
trivial_casts,
trivial_numeric_casts,
unused_extern_crates,
unused_import_braces,
unused_qualifications,
unused_results
)]
#![allow(
box_pointers,
missing_copy_implementations,
missing_debug_implementations,
variant_size_differences
)]
#[cfg(test)]
extern crate rand;
use std::collections::VecDeque;
use tiny_keccak::{Hasher, Sha3};
pub struct ResourceProof {
min_size: usize,
difficulty: u8,
}
impl ResourceProof {
pub fn new(min_size: usize, difficulty: u8) -> ResourceProof {
ResourceProof {
min_size,
difficulty,
}
}
pub fn create_proof_data(&self, nonce: &[u8]) -> VecDeque<u8> {
nonce.iter().cloned().cycle().take(self.min_size).collect()
}
pub fn create_prover(&self, data: VecDeque<u8>) -> ResourceProver {
ResourceProver {
difficulty: self.difficulty,
count: 0,
data,
}
}
pub fn validate_all(&self, nonce: &[u8], received_data: &VecDeque<u8>, key: u64) -> bool {
let mut data = self.create_proof_data(nonce);
if data != *received_data {
return false;
}
for _ in 0..key {
data.push_front(0u8);
}
self.check_hash(&data) >= self.difficulty
}
pub fn validate_data(&self, nonce: &[u8], data: &VecDeque<u8>) -> bool {
self.create_proof_data(nonce) == *data
}
pub fn validate_proof(&self, nonce: &[u8], key: u64) -> bool {
let mut data = self.create_proof_data(nonce);
for _ in 0..key {
data.push_front(0u8);
}
self.check_hash(&data) >= self.difficulty
}
fn check_hash(&self, data: &VecDeque<u8>) -> u8 {
ResourceProof::leading_zeros(&hash(&data.as_slices()))
}
fn leading_zeros(data: &[u8]) -> u8 {
let mut zeros = 0u8;
for (count, i) in data.iter().enumerate() {
zeros = i.leading_zeros() as u8 + (count as u8 * 8);
if i.leading_zeros() < 8 {
break;
}
}
zeros
}
}
pub struct ResourceProver {
difficulty: u8,
count: u64,
data: VecDeque<u8>,
}
impl ResourceProver {
pub fn expected_steps(&self) -> u64 {
2u64.pow(u32::from(self.difficulty))
}
pub fn try_step(&mut self) -> Option<u64> {
if self.check_hash() >= self.difficulty {
return Some(self.count);
}
self.data.push_front(0u8);
self.count += 1;
None
}
pub fn solve(&mut self) -> u64 {
loop {
if let Some(solution) = self.try_step() {
return solution;
}
}
}
fn check_hash(&self) -> u8 {
ResourceProof::leading_zeros(&hash(&self.data.as_slices()))
}
}
fn hash(data: &(&[u8], &[u8])) -> [u8; 32] {
let mut hasher = Sha3::v256();
let mut res = [0u8; 32];
hasher.update(data.0);
hasher.update(data.1);
hasher.finalize(&mut res);
res
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn valid_proof() {
for _ in 0..20 {
let nonce = [rand::random::<u8>()];
let rp = ResourceProof::new(1024, 3);
let data = rp.create_proof_data(&nonce);
let proof = rp.create_prover(data.clone()).solve();
assert!(rp.validate_proof(&nonce, proof));
assert!(rp.validate_data(&nonce, &data));
assert!(rp.validate_all(&nonce, &data, proof));
}
}
}