Initial commit.

pull/3/head
Sean Bowe 8 years ago
commit 1c09fdc74e
  1. 2
      .gitignore
  2. 7
      Cargo.toml
  3. 362
      src/lib.rs
  4. 68
      src/sha256.rs

2
.gitignore vendored

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target
Cargo.lock

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[package]
name = "incrementalmerkletree"
version = "0.1.0"
authors = ["Sean Bowe <ewillbefull@gmail.com>"]
[dependencies]
rand = "0.3"

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#![feature(rustc_private)]
extern crate rustc;
extern crate rand;
mod sha256;
trait Hashable: Clone + Copy {
fn combine(&Self, &Self) -> Self;
fn blank() -> Self;
}
#[derive(Clone)]
struct IncrementalMerkleTree<T: Hashable> {
cursor: Leaf<T>,
depth: usize
}
#[derive(Clone)]
enum Leaf<T: Hashable> {
Left{parent: Parent<T>, content: T},
Right{parent: Parent<T>, left: T, content: T}
}
#[derive(Clone)]
enum Parent<T: Hashable> {
Empty,
Left{parent: Box<Parent<T>>},
Right{left: T, parent: Box<Parent<T>>}
}
impl<T: Hashable> Parent<T> {
fn ascend<'a, F: FnMut(Option<&'a T>) -> bool>(&'a self, mut cb: F) {
match *self {
Parent::Empty => {
if cb(None) {
self.ascend(cb);
}
},
Parent::Left{ref parent} => {
if cb(None) {
parent.ascend(cb);
}
},
Parent::Right{ref left, ref parent} => {
if cb(Some(left)) {
parent.ascend(cb);
}
}
}
}
fn advance(self, hash: T) -> Parent<T> {
match self {
Parent::Empty => {
Parent::Right {
left: hash,
parent: Box::new(Parent::Empty)
}
},
Parent::Left{parent} => {
Parent::Right {
left: hash,
parent: parent
}
},
Parent::Right{left, parent} => {
Parent::Left{
parent: Box::new(parent.advance(T::combine(&left, &hash)))
}
}
}
}
}
impl<T: Hashable> IncrementalMerkleTree<T> {
fn new(d: usize, initial: T) -> IncrementalMerkleTree<T> {
assert!(d != 0);
IncrementalMerkleTree {
cursor: Leaf::Left{parent: Parent::Empty, content: initial},
depth: d
}
}
fn completed(&self) -> bool {
match self.cursor {
Leaf::Left{..} => false,
Leaf::Right{ref parent, ..} => {
let complete = &mut true;
let depth = &mut (self.depth - 1);
parent.ascend(|left| {
if *depth == 0 {
return false;
}
if left.is_none() {
*complete = false;
return false;
}
*depth -= 1;
true
});
*complete
}
}
}
fn append(self, obj: T) -> IncrementalMerkleTree<T> {
match self.cursor {
Leaf::Left{parent, content} => {
IncrementalMerkleTree {
cursor: Leaf::Right{
parent: parent,
left: content,
content: obj
},
depth: self.depth
}
},
Leaf::Right{parent, left, content} => {
IncrementalMerkleTree {
cursor: Leaf::Left{
parent: parent.advance(T::combine(&left, &content)),
content: obj
},
depth: self.depth
}
}
}
}
fn unfilled(&self, mut skip: usize) -> usize {
let parent = match self.cursor {
Leaf::Left{ref parent, ..} => {
if skip == 0 {
return 0;
} else {
skip -= 1;
parent
}
},
Leaf::Right{ref parent, ..} => {
parent
}
};
let mut depth = &mut 0;
parent.ascend(|left| {
*depth += 1;
match left {
Some(_) => {
return true;
},
None => {
if skip == 0 {
return false;
} else {
skip -= 1;
return true;
}
}
}
});
return *depth;
}
fn root(&self) -> T {
self.root_advanced(Some(T::blank()).iter().cycle())
}
fn root_advanced<'a, I: Iterator<Item=&'a T>>(&self, mut it: I) -> T where T: 'a {
let (parent, mut child) = match self.cursor {
Leaf::Left{ref parent, ref content} => {
(parent, T::combine(content, it.next().unwrap()))
},
Leaf::Right{ref parent, ref left, ref content} => {
(parent, T::combine(left, content))
}
};
let mut depth = self.depth - 1;
{
let child = &mut child;
parent.ascend(move |left| {
if depth == 0 {
return false;
}
match left {
Some(left) => {
*child = T::combine(left, &*child);
},
None => {
*child = T::combine(&*child, it.next().unwrap());
}
}
depth = depth - 1;
true
});
}
return child;
}
}
#[derive(Clone)]
struct IncrementalWitness<T: Hashable> {
tree: IncrementalMerkleTree<T>,
delta: IncrementalDelta<T>
}
#[derive(Clone)]
struct IncrementalDelta<T: Hashable> {
filled: Vec<T>,
active: Option<IncrementalMerkleTree<T>>
}
impl<T: Hashable> IncrementalWitness<T> {
fn new(from: &IncrementalMerkleTree<T>) -> IncrementalWitness<T> {
IncrementalWitness {
tree: from.clone(),
delta: IncrementalDelta {
filled: vec![],
active: None
}
}
}
fn append(&mut self, object: T) {
match self.delta.active.take() {
Some(active) => {
let active = active.append(object);
if active.completed() {
self.delta.filled.push(active.root());
} else {
self.delta.active = Some(active);
}
},
None => {
match self.tree.unfilled(self.delta.filled.len()) {
0 => {
self.delta.filled.push(object);
},
i => {
self.delta.active = Some(IncrementalMerkleTree::new(i, object));
}
}
}
}
}
fn root(&self) -> T {
self.tree.root_advanced(self.delta.filled.iter() // use filled values
.chain(self.delta.active.as_ref().map(|x| x.root()).as_ref()) // then use the active root
.chain(Some(T::blank()).iter().cycle())) // then fill in with blanks
}
}
mod test {
use super::{IncrementalMerkleTree, IncrementalWitness};
use super::sha256::*;
#[test]
fn test_root() {
let a = Sha256Digest::rand(0);
let tree = IncrementalMerkleTree::new(3, a);
assert_eq!(tree.root(), Sha256Digest([94, 162, 216, 229, 230, 128, 153, 35, 89, 40, 180, 159, 125, 27, 48, 80, 181, 73, 7, 195, 182, 223, 83, 165, 59, 200, 234, 181, 106, 3, 243, 228]));
let b = Sha256Digest::rand(1);
let tree = tree.append(b);
assert_eq!(tree.root(), Sha256Digest([222, 23, 196, 222, 130, 80, 115, 139, 134, 72, 108, 150, 235, 75, 216, 5, 63, 101, 2, 237, 51, 47, 165, 216, 40, 15, 209, 176, 10, 192, 224, 26]));
}
#[test]
fn test_unfilled() {
let a = Sha256Digest::rand(0);
let mut tree = IncrementalMerkleTree::new(3, a);
for i in 0..4 {
let b = Sha256Digest::rand(i+1);
tree = tree.append(b);
}
assert_eq!(tree.unfilled(0), 0);
assert_eq!(tree.unfilled(1), 1);
assert_eq!(tree.unfilled(2), 3);
}
#[test]
fn test_complete() {
let a = Sha256Digest::rand(0);
let mut tree = IncrementalMerkleTree::new(3, a);
for i in 0..7 {
assert_eq!(tree.completed(), false);
let b = Sha256Digest::rand(i+1);
tree = tree.append(b);
}
assert_eq!(tree.completed(), true);
}
#[test]
fn test_witness() {
let a = Sha256Digest::rand(0);
let mut tree = IncrementalMerkleTree::new(3, a);
let mut witness = IncrementalWitness::new(&tree);
assert_eq!(tree.root(), witness.root());
assert_eq!(witness.delta.filled.len(), 0);
assert!(witness.delta.active.is_none());
for i in 1..8 {
let b = Sha256Digest::rand(i);
witness.append(b);
tree = tree.append(b);
match i {
1 => {
assert_eq!(witness.delta.filled.len(), 1);
assert!(witness.delta.active.is_none());
},
i if i <= 2 => {
assert_eq!(witness.delta.filled.len(), 1);
assert!(witness.delta.active.is_some());
},
i if i == 3 => {
assert_eq!(witness.delta.filled.len(), 2);
assert!(witness.delta.active.is_none());
},
i if i < 7 => {
assert_eq!(witness.delta.filled.len(), 2);
assert!(witness.delta.active.is_some());
},
a @ _ => {
assert_eq!(a, 7);
assert_eq!(witness.delta.filled.len(), 3);
assert!(witness.delta.active.is_none());
}
}
assert_eq!(tree.root(), witness.root());
}
}
}

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use rustc::util::sha2::{Digest,Sha256};
use std::u8;
use super::Hashable;
impl Hashable for Sha256Digest {
fn combine(left: &Self, right: &Self) -> Sha256Digest {
sha256_compression_function(Sha256Block::new_from_digests(left, right))
}
fn blank() -> Sha256Digest {
Sha256Digest([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
}
}
struct Sha256Block(pub [u8; 64]);
impl Sha256Block {
fn new_from_digests(left: &Sha256Digest, right: &Sha256Digest) -> Sha256Block {
use std::mem;
struct CompoundDigest {
left: Sha256Digest,
right: Sha256Digest
}
let compound = CompoundDigest { left: *left, right: *right };
unsafe { mem::transmute(compound) }
}
}
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
pub struct Sha256Digest(pub [u8; 32]);
impl Sha256Digest {
pub fn rand(seed: usize) -> Sha256Digest {
use rand::{self,Rng,SeedableRng,StdRng};
let seed: [usize; 1] = [seed];
let mut rng = StdRng::from_seed(&seed);
Sha256Digest([rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(),
rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(),
rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(),
rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen(), rng.gen()
])
}
}
// todo: this is not a compression function
fn sha256_compression_function(block: Sha256Block) -> Sha256Digest {
let mut hash = Sha256::new();
hash.input(&block.0);
let res = hash.result_bytes();
let mut s = Sha256Digest([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
unsafe {
use std::ptr;
ptr::copy_nonoverlapping::<u8>(&res[0], &mut (s.0)[0], 32);
}
s
}
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