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Cleaned up more of the project and improved readme

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Robert Kornacki 2019-07-22 15:04:45 -04:00
parent 7144bc2f34
commit 6b591947d0
4 changed files with 132 additions and 240 deletions
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3
Cargo.toml
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@ -6,7 +6,6 @@ description = """
SHA256 PoW on any serializable datatype.
"""
edition = "2018"
# documentation = "https://docs.rs/PoW"
keywords = ["PoW", "sha256", "proof-of-work"]
readme = "readme.md"
license = "MIT OR Apache-2.0"
@ -14,5 +13,5 @@ repository = "https://github.com/robkorn/pow"
categories = [] # pr me!
[dependencies]
sha2 = "0.8.0"
serde = { version = "1", features = ["derive"] }
serde = { version = "1.0.97", features = ["derive"] }
bincode = "1.1.4"

11
readme.md → README.md
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@ -1,8 +1,13 @@
# PoW
# PoW-SHA256
Sha256 based proof of work over a typed piece of data.
Rust crate which generates SHA256 Proofs of Work on serializable datatypes. Any type that implements `serde::Deserialize` can be used.
Any type that implementes serde::Deserialize can be tagged with a proof of work.
This is a fork of the [`Pow` library](https://github.com/bddap/pow) by bddap with some new additions. Primary of these being:
- PoW datatype now saves the calculation result to be used for checking proof validity given input
- `is_valid_proof` method to do the above mentioned
Other small changes have also been included of various importance but mostly just stylistic/ease of use improvements.
# Examples

219
src/lib.rs
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@ -1,112 +1,139 @@
// Sha256 based proof of work over a typed piece of data.
use serde::{Deserialize, Serialize};
use sha2::{digest::FixedOutput, Digest, Sha256};
use std::marker::PhantomData;
// Any type that implementes serde::Deserialize can be tagged with a proof of work.
const SALT: &str = "79ziepia7vhjgviiwjhnend3ofjqocsi2winc4ptqhmkvcajihywxcizewvckg9h6gs4j83v9";
// # Examples
/// Proof of Work over concrete type T. T can be any type that implements serde::Serialize.
#[derive(Serialize, Deserialize, PartialEq, Clone, Copy, Debug)]
pub struct PoW<T> {
nonce: u128,
result: u128,
_spook: PhantomData<T>,
}
// Prove we did work targeting a phrase.
impl<T: Serialize> PoW<T> {
/// Create Proof of Work over item of type T.
///
/// Make sure difficulty is not too high. A 64 bit difficulty, for example, takes a long time
/// on a general purpose processor.
///
/// Returns bincode::Error if serialization fails.
pub fn prove_work(t: &T, difficulty: u128) -> bincode::Result<PoW<T>> {
bincode_cfg()
.serialize(t)
.map(|v| Self::prove_work_serialized(&v, difficulty))
}
// ```rust
// use PoW::PoW;
/// Create Proof of Work on an already serialized item of type T.
/// The input is assumed to be serialized using network byte order.
///
/// Make sure difficulty is not too high. A 64 bit difficulty, for example, takes a long time
/// on a general purpose processor.
pub fn prove_work_serialized(prefix: &[u8], difficulty: u128) -> PoW<T> {
let prefix_sha = Sha256::new().chain(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,
_spook: PhantomData,
}
}
// // very easy mode
// let difficulty = u128::max_value() - u128::max_value() / 2;
/// Calculate the PoW score with the provided input T.
pub fn calculate(&self, t: &T) -> bincode::Result<u128> {
bincode_cfg()
.serialize(t)
.map(|v| self.calculate_serialized(&v))
}
// let phrase = b"Phrase to tag.".to_vec();
// let pw = PoW::prove_work(&phrase, difficulty).unwrap();
// assert!(pw.calculate(&phrase).unwrap() >= difficulty);
// ```
/// Calculate the PoW score of an already serialized T and self.
/// The input is assumed to be serialized using network byte order.
pub fn calculate_serialized(&self, target: &[u8]) -> u128 {
score(Sha256::new().chain(SALT).chain(target), self.nonce)
}
// Prove more difficult work. This time targeting a time.
/// Verifies that the PoW is indeed generated out of the phrase provided.
pub fn is_valid_proof(&self, t: &T) -> bool {
match self.calculate(t) {
Ok(res) => if self.result == res {return true;},
Err(_) => return false
}
return false;
}
}
// ```rust
// # fn get_unix_time_seconds() -> u64 {
// # use std::time::{Duration, SystemTime};
// # SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs()
// # }
// # use PoW::PoW;
fn score(prefix_sha: Sha256, nonce: u128) -> u128 {
first_bytes_as_u128(
prefix_sha
.chain(&nonce.to_be_bytes()) // to_be_bytes() converts to network endian
.fixed_result()
.as_slice(),
)
}
// // more diffcult, takes around 100_000 hashes to generate proof
// let difficulty = u128::max_value() - u128::max_value() / 100_000;
/// # Panics
///
/// panics if inp.len() < 16
fn first_bytes_as_u128(inp: &[u8]) -> u128 {
bincode_cfg().deserialize(&inp).unwrap()
}
// let now: u64 = get_unix_time_seconds();
// let pw = PoW::prove_work(&now, difficulty).unwrap();
// assert!(pw.calculate(&now).unwrap() >= difficulty);
// ```
fn bincode_cfg() -> bincode::Config {
let mut cfg = bincode::config();
cfg.big_endian();
cfg
}
// Define a blockchain block.
#[cfg(test)]
mod test {
use super::*;
// ```rust
// # use PoW::PoW;
// struct Block<T> {
// prev: [u8; 32], // hash of last block
// payload: T, // generic data
// proof_of_work: PoW<([u8; 32], T)>,
// }
// ```
const DIFFICULTY: u128 = 0xff000000000000000000000000000000;
// # Score scheme
#[test]
fn base_functionality() {
// Let's prove we did work targeting a phrase.
let phrase = b"Ex nihilo nihil fit.".to_vec();
let pw = PoW::prove_work(&phrase, DIFFICULTY).unwrap();
assert!(pw.calculate(&phrase).unwrap() >= DIFFICULTY);
assert!(pw.is_valid_proof(&phrase));
}
// To score a proof of work for a given (target, PoW) pair:
// Sha256 is calculated over the concatenation SALT + target + PoW.
// The first 16 bytes of the hash are interpreted as a 128 bit unsigned integer.
// That integer is the score.
// A constant, SALT, is used as prefix to prevent PoW reuse from other systems such as proof
// of work blockchains.
#[test]
fn double_pow() {
let phrase = "Ex nihilo nihil fit.".to_owned();
let pw = PoW::prove_work(&phrase, DIFFICULTY).unwrap();
let pwpw: PoW<PoW<String>> = PoW::prove_work(&pw, DIFFICULTY).unwrap();
assert!(pw.calculate(&phrase).unwrap() >= DIFFICULTY);
assert!(pwpw.calculate(&pw).unwrap() >= DIFFICULTY);
assert!(pwpw.is_valid_proof(&pw));
}
// In other words:
#[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 pw = PoW::prove_work(&phrase, DIFFICULTY).unwrap();
let pw2 = PoW::prove_work(&phrase2, DIFFICULTY).unwrap();
assert!(!pw.is_valid_proof(&phrase2));
assert!(!pw2.is_valid_proof(&phrase));
}
// ```rust
// # use serde::Serialize;
// # use PoW::PoW;
// # use core::any::Any;
// # const SALT: &'static str = "not the actual salt used";
// # fn serialize<T: Serialize>(_: &T) -> u8 { 0 } // not the actual serialize function
// # fn deserialize(_: &[u8]) -> u128 { 0 } // not the actual deserialize function
// # fn sha256(_: &u8) -> [u8; 32] { [0; 32] } // not the actual sha256 function
// fn score<T: Serialize>(target: &T, PoW_tag: &PoW<T>) -> u128 {
// let bytes = serialize(&SALT) + serialize(target) + serialize(PoW_tag);
// let hash = sha256(&bytes);
// deserialize(&hash[..16])
// }
// ```
// # Serialization encoding.
// It shouldn't matter to users of this library, but the bincode crate is used for cheap
// deterministic serialization. All values are serialized using network byte order.
// # Threshold scheme
// Given a minimum score m. A PoW p satisfies the minimum score for target t iff score(t, p) >= m.
// # Choosing a difficulty setting.
// Difficulty settings are usually best adjusted dynamically a la bitcoin.
// To manually select a difficulty, choose the average number of hashes required.
// ```rust
// fn difficulty(average: u128) -> u128 {
// debug_assert_ne!(average, 0, "It is impossible to prove work in zero attempts.");
// let m = u128::max_value();
// m - m / average
// }
// ```
// Conversely, to calculate probable number of hashes required to satisfy a given minimum
// difficulty.
// ```rust
// fn average(difficulty: u128) -> u128 {
// let m = u128::max_value();
// if difficulty == m {
// return m;
// }
// m / (m - difficulty)
// }
// ```
mod proof_of_work;
pub use proof_of_work::PoW;
#[test]
fn serialization_test() {
let target: u8 = 1;
let pw = PoW::prove_work(&target, DIFFICULTY).unwrap();
let message: (u8, PoW<u8>) = (target, pw);
let message_ser = bincode_cfg().serialize(&message).unwrap();
let recieved_message: (u8, PoW<u8>) = bincode_cfg().deserialize(&message_ser).unwrap();
assert_eq!(recieved_message, message);
assert!(message.1.calculate(&message.0).unwrap() >= DIFFICULTY);
assert!(message.1.is_valid_proof(&target));
}
}

139
src/proof_of_work.rs
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@ -1,139 +0,0 @@
use serde::{Deserialize, Serialize};
use sha2::{digest::FixedOutput, Digest, Sha256};
use std::marker::PhantomData;
const SALT: &str = "79ziepia7vhjgviiwjhnend3ofjqocsi2winc4ptqhmkvcajihywxcizewvckg9h6gs4j83v9";
/// Proof of Work over concrete type T. T can be any type that implements serde::Serialize.
#[derive(Serialize, Deserialize, PartialEq, Clone, Copy, Debug)]
pub struct PoW<T> {
nonce: u128,
result: u128,
_spook: PhantomData<T>,
}
// prove_work and calculate could theoretically be without allocations, by serializing to a Write
// implementaion that performs sha256 lazily.
// `impl io::Write for sha2::Sha256 { ... }`
impl<T: Serialize> PoW<T> {
/// Create Proof of Work over item of type T.
///
/// Make sure difficulty is not too high. A 64 bit difficulty, for example, takes a long time
/// on a general purpose processor.
///
/// Returns bincode::Error if serialization fails.
pub fn prove_work(t: &T, difficulty: u128) -> bincode::Result<PoW<T>> {
bincode_cfg()
.serialize(t)
.map(|v| Self::prove_work_serialized(&v, difficulty))
}
/// Create Proof of Work on an already serialized item of type T.
/// The input is assumed to be serialized using network byte order.
///
/// Make sure difficulty is not too high. A 64 bit difficulty, for example, takes a long time
/// on a general purpose processor.
pub fn prove_work_serialized(prefix: &[u8], difficulty: u128) -> PoW<T> {
let prefix_sha = Sha256::new().chain(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,
_spook: PhantomData,
}
}
/// Calculate the PoW score of t and self.
pub fn calculate(&self, t: &T) -> bincode::Result<u128> {
bincode_cfg()
.serialize(t)
.map(|v| self.calculate_serialized(&v))
}
/// Calculate the PoW score of an already serialized T and self.
/// The input is assumed to be serialized using network byte order.
pub fn calculate_serialized(&self, target: &[u8]) -> u128 {
score(Sha256::new().chain(SALT).chain(target), self.nonce)
}
pub fn is_valid_proof(&self, t: &T) -> bool {
if self.result == self.calculate(t).unwrap() {
return true;
}
return false;
}
}
fn score(prefix_sha: Sha256, nonce: u128) -> u128 {
first_bytes_as_u128(
prefix_sha
.chain(&nonce.to_be_bytes()) // to_be_bytes() converts to network endian
.fixed_result()
.as_slice(),
)
}
/// # Panics
///
/// panics if inp.len() < 16
fn first_bytes_as_u128(inp: &[u8]) -> u128 {
bincode_cfg().deserialize(&inp).unwrap()
}
fn bincode_cfg() -> bincode::Config {
let mut cfg = bincode::config();
cfg.big_endian();
cfg
}
#[cfg(test)]
mod test {
use super::*;
const DIFFICULTY: u128 = 0xff000000000000000000000000000000;
#[test]
fn base_functionality() {
// Let's prove we did work targeting a phrase.
let phrase = b"Ex nihilo nihil fit.".to_vec();
let pw = PoW::prove_work(&phrase, DIFFICULTY).unwrap();
assert!(pw.calculate(&phrase).unwrap() >= DIFFICULTY);
assert!(pw.is_valid_proof(&phrase));
}
#[test]
fn double_pow() {
let phrase = "Ex nihilo nihil fit.".to_owned();
let pw = PoW::prove_work(&phrase, DIFFICULTY).unwrap();
let pwpw: PoW<PoW<String>> = PoW::prove_work(&pw, DIFFICULTY).unwrap();
assert!(pw.calculate(&phrase).unwrap() >= DIFFICULTY);
assert!(pwpw.calculate(&pw).unwrap() >= 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 pw = PoW::prove_work(&phrase, DIFFICULTY).unwrap();
let pw2 = PoW::prove_work(&phrase2, DIFFICULTY).unwrap();
assert!(!pw.is_valid_proof(&phrase2));
assert!(!pw2.is_valid_proof(&phrase));
}
#[test]
fn ser_de() {
let target: u8 = 1;
let pw = PoW::prove_work(&target, DIFFICULTY).unwrap();
let message: (u8, PoW<u8>) = (target, pw);
let message_ser = bincode_cfg().serialize(&message).unwrap();
let recieved_message: (u8, PoW<u8>) = bincode_cfg().deserialize(&message_ser).unwrap();
assert_eq!(recieved_message, message);
assert!(message.1.calculate(&message.0).unwrap() >= DIFFICULTY);
}
}