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Merge pull request #248 from str4d/equihash-crate 

Move Equihash verifier into equihash crate
This commit is contained in:
str4d 2020-07-10 11:57:11 +12:00 committed by GitHub
parent d380a8c8d2 b5bd52e7a1
commit f55f094ef6
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GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 166 additions and 72 deletions
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1
Cargo.toml
View File

@ -1,6 +1,7 @@
[workspace]
members = [
"bellman",
"components/equihash",
"ff",
"group",
"pairing",

13
components/equihash/Cargo.toml Normal file
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@ -0,0 +1,13 @@
[package]
name = "equihash"
description = "The Equihash Proof-of-Work function"
version = "0.1.0"
authors = ["Jack Grigg <jack@z.cash>"]
homepage = "https://github.com/zcash/librustzcash"
repository = "https://github.com/zcash/librustzcash"
license = "MIT OR Apache-2.0"
edition = "2018"
[dependencies]
blake2b_simd = "0.5"
byteorder = "1"

22
components/equihash/src/lib.rs Normal file
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@ -0,0 +1,22 @@
//! Equihash is a Proof-of-Work algorithm, based on a generalization of the Birthday
//! problem which finds colliding hash values. It was designed to be memory-hard; more
//! specifically, the bottle-neck for parallel implementations of Equihash solvers would
//! be memory bandwidth.
//!
//! This crate implements Equihash as specified for the Zcash consensus rules. It can
//! verify solutions for any valid `(n, k)` parameters, as long as the row indices are no
//! larger than 32 bits (that is, `ceiling(((n / (k + 1)) + 1) / 8) <= 4`).
//!
//! References
//! ==========
//! - [Section 7.6.1: Equihash.] Zcash Protocol Specification, version 2020.1.10 or later.
//! - Alex Biryukov and Dmitry Khovratovich.
//! [*Equihash: Asymmetric Proof-of-Work Based on the Generalized Birthday Problem.*][BK16]
//! NDSS ’16.
//!
//! [Section 7.6.1: Equihash.]: https://zips.z.cash/protocol/protocol.pdf#equihash
//! [BK16]: https://www.internetsociety.org/sites/default/files/blogs-media/equihash-asymmetric-proof-of-work-based-generalized-birthday-problem.pdf
mod verify;
pub use verify::{is_valid_solution, Error};

199
zcash_primitives/src/block/equihash.rs → components/equihash/src/verify.rs
View File

@ -4,10 +4,11 @@
use blake2b_simd::{Hash as Blake2bHash, Params as Blake2bParams, State as Blake2bState};
use byteorder::{BigEndian, LittleEndian, ReadBytesExt, WriteBytesExt};
use log::error;
use std::fmt;
use std::io::Cursor;
use std::mem::size_of;
#[derive(Clone, Copy)]
struct Params {
n: u32,
k: u32,
@ -20,6 +21,18 @@ struct Node {
}
impl Params {
fn new(n: u32, k: u32) -> Result<Self, Error> {
// We place the following requirements on the parameters:
// - n is a multiple of 8, so the hash output has an exact byte length.
// - k >= 3 so the encoded solutions have an exact byte length.
// - k < n, so the collision bit length is at least 1.
// - n is a multiple of k + 1, so we have an integer collision bit length.
if (n % 8 == 0) && (k >= 3) && (k < n) && (n % (k + 1) == 0) {
Ok(Params { n, k })
} else {
Err(Error(Kind::InvalidParams))
}
}
fn indices_per_hash_output(&self) -> u32 {
512 / self.n
}
@ -32,6 +45,7 @@ impl Params {
fn collision_byte_length(&self) -> usize {
(self.collision_bit_length() + 7) / 8
}
#[cfg(test)]
fn hash_length(&self) -> usize {
((self.k as usize) + 1) * self.collision_byte_length()
}
@ -68,6 +82,7 @@ impl Node {
Node { hash, indices }
}
#[cfg(test)]
fn from_children_ref(a: &Node, b: &Node, trim: usize) -> Self {
let hash: Vec<_> = a
.hash
@ -98,6 +113,39 @@ impl Node {
}
}
/// An Equihash solution failed to verify.
#[derive(Debug)]
pub struct Error(Kind);
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Invalid solution: {}", self.0)
}
}
impl std::error::Error for Error {}
#[derive(Debug)]
enum Kind {
InvalidParams,
Collision,
OutOfOrder,
DuplicateIdxs,
NonZeroRootHash,
}
impl fmt::Display for Kind {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Kind::InvalidParams => f.write_str("invalid parameters"),
Kind::Collision => f.write_str("invalid collision length between StepRows"),
Kind::OutOfOrder => f.write_str("Index tree incorrectly ordered"),
Kind::DuplicateIdxs => f.write_str("duplicate indices"),
Kind::NonZeroRootHash => f.write_str("root hash of tree is non-zero"),
}
}
}
fn initialise_state(n: u32, k: u32, digest_len: u8) -> Blake2bState {
let mut personalization: Vec<u8> = Vec::from("ZcashPoW");
personalization.write_u32::<LittleEndian>(n).unwrap();
@ -163,7 +211,13 @@ fn expand_array(vin: &[u8], bit_len: usize, byte_pad: usize) -> Vec<u8> {
vout
}
fn indices_from_minimal(minimal: &[u8], c_bit_len: usize) -> Vec<u32> {
fn indices_from_minimal(p: Params, minimal: &[u8]) -> Result<Vec<u32>, Error> {
let c_bit_len = p.collision_bit_length();
// Division is exact because k >= 3.
if minimal.len() != ((1 << p.k) * (c_bit_len + 1)) / 8 {
return Err(Error(Kind::InvalidParams));
}
assert!(((c_bit_len + 1) + 7) / 8 <= size_of::<u32>());
let len_indices = 8 * size_of::<u32>() * minimal.len() / (c_bit_len + 1);
let byte_pad = size_of::<u32>() - ((c_bit_len + 1) + 7) / 8;
@ -177,7 +231,7 @@ fn indices_from_minimal(minimal: &[u8], c_bit_len: usize) -> Vec<u32> {
ret.push(i);
}
ret
Ok(ret)
}
fn has_collision(a: &Node, b: &Node, len: usize) -> bool {
@ -199,30 +253,25 @@ fn distinct_indices(a: &Node, b: &Node) -> bool {
true
}
fn validate_subtrees(p: &Params, a: &Node, b: &Node) -> bool {
fn validate_subtrees(p: &Params, a: &Node, b: &Node) -> Result<(), Kind> {
if !has_collision(a, b, p.collision_byte_length()) {
error!("Invalid solution: invalid collision length between StepRows");
false
Err(Kind::Collision)
} else if b.indices_before(a) {
error!("Invalid solution: Index tree incorrectly ordered");
false
Err(Kind::OutOfOrder)
} else if !distinct_indices(a, b) {
error!("Invalid solution: duplicate indices");
false
Err(Kind::DuplicateIdxs)
} else {
true
Ok(())
}
}
pub fn is_valid_solution_iterative(
n: u32,
k: u32,
#[cfg(test)]
fn is_valid_solution_iterative(
p: Params,
input: &[u8],
nonce: &[u8],
indices: &[u32],
) -> bool {
let p = Params { n, k };
) -> Result<(), Error> {
let mut state = initialise_state(p.n, p.k, p.hash_output());
state.update(input);
state.update(nonce);
@ -238,9 +287,7 @@ pub fn is_valid_solution_iterative(
for pair in rows.chunks(2) {
let a = &pair[0];
let b = &pair[1];
if !validate_subtrees(&p, a, b) {
return false;
}
validate_subtrees(&p, a, b).map_err(Error)?;
cur_rows.push(Node::from_children_ref(a, b, p.collision_byte_length()));
}
rows = cur_rows;
@ -248,71 +295,81 @@ pub fn is_valid_solution_iterative(
}
assert!(rows.len() == 1);
rows[0].is_zero(hash_len)
}
fn tree_validator(p: &Params, state: &Blake2bState, indices: &[u32]) -> Option<Node> {
if indices.len() > 1 {
let end = indices.len();
let mid = end / 2;
match (
tree_validator(p, state, &indices[0..mid]),
tree_validator(p, state, &indices[mid..end]),
) {
(Some(a), Some(b)) => {
if validate_subtrees(p, &a, &b) {
Some(Node::from_children(a, b, p.collision_byte_length()))
} else {
None
}
}
_ => None,
}
if rows[0].is_zero(hash_len) {
Ok(())
} else {
Some(Node::new(&p, &state, indices[0]))
Err(Error(Kind::NonZeroRootHash))
}
}
pub fn is_valid_solution_recursive(
n: u32,
k: u32,
fn tree_validator(p: &Params, state: &Blake2bState, indices: &[u32]) -> Result<Node, Error> {
if indices.len() > 1 {
let end = indices.len();
let mid = end / 2;
let a = tree_validator(p, state, &indices[0..mid])?;
let b = tree_validator(p, state, &indices[mid..end])?;
validate_subtrees(p, &a, &b).map_err(Error)?;
Ok(Node::from_children(a, b, p.collision_byte_length()))
} else {
Ok(Node::new(&p, &state, indices[0]))
}
}
fn is_valid_solution_recursive(
p: Params,
input: &[u8],
nonce: &[u8],
indices: &[u32],
) -> bool {
let p = Params { n, k };
) -> Result<(), Error> {
let mut state = initialise_state(p.n, p.k, p.hash_output());
state.update(input);
state.update(nonce);
match tree_validator(&p, &state, indices) {
Some(root) => {
// Hashes were trimmed, so only need to check remaining length
root.is_zero(p.collision_byte_length())
}
None => false,
let root = tree_validator(&p, &state, indices)?;
// Hashes were trimmed, so only need to check remaining length
if root.is_zero(p.collision_byte_length()) {
Ok(())
} else {
Err(Error(Kind::NonZeroRootHash))
}
}
pub fn is_valid_solution(n: u32, k: u32, input: &[u8], nonce: &[u8], soln: &[u8]) -> bool {
let p = Params { n, k };
let indices = indices_from_minimal(soln, p.collision_bit_length());
/// Checks whether `soln` is a valid solution for `(input, nonce)` with the
/// parameters `(n, k)`.
pub fn is_valid_solution(
n: u32,
k: u32,
input: &[u8],
nonce: &[u8],
soln: &[u8],
) -> Result<(), Error> {
let p = Params::new(n, k)?;
let indices = indices_from_minimal(p, soln)?;
// Recursive validation is faster
is_valid_solution_recursive(n, k, input, nonce, &indices)
is_valid_solution_recursive(p, input, nonce, &indices)
}
#[cfg(test)]
mod tests {
use super::is_valid_solution_iterative;
use super::is_valid_solution_recursive;
use super::{Error, Params};
fn is_valid_solution(n: u32, k: u32, input: &[u8], nonce: &[u8], indices: &[u32]) -> bool {
let a = is_valid_solution_iterative(n, k, input, nonce, indices);
let b = is_valid_solution_recursive(n, k, input, nonce, indices);
assert!(a == b);
a
fn is_valid_solution(
n: u32,
k: u32,
input: &[u8],
nonce: &[u8],
indices: &[u32],
) -> Result<(), Error> {
let p = Params::new(n, k).unwrap();
is_valid_solution_iterative(p, input, nonce, indices)?;
is_valid_solution_recursive(p, input, nonce, indices)?;
Ok(())
}
#[test]
@ -324,14 +381,14 @@ mod tests {
25557, 92292, 38525, 56514, 1110, 98024, 15426, 74455, 3185, 84007, 24328, 36473,
17427, 129451, 27556, 119967, 31704, 62448, 110460, 117894,
];
assert!(is_valid_solution(96, 5, input, &nonce, &indices));
is_valid_solution(96, 5, input, &nonce, &indices).unwrap();
indices = vec![
1008, 18280, 34711, 57439, 3903, 104059, 81195, 95931, 58336, 118687, 67931, 123026,
64235, 95595, 84355, 122946, 8131, 88988, 45130, 58986, 59899, 78278, 94769, 118158,
25569, 106598, 44224, 96285, 54009, 67246, 85039, 127667,
];
assert!(is_valid_solution(96, 5, input, &nonce, &indices));
is_valid_solution(96, 5, input, &nonce, &indices).unwrap();
indices = vec![
4313, 223176, 448870, 1692641, 214911, 551567, 1696002, 1768726, 500589, 938660,
@ -387,19 +444,19 @@ mod tests {
981619, 683206, 1485056, 766481, 2047708, 930443, 2040726, 1136227, 1945705, 1722044,
1971986,
];
assert!(!is_valid_solution(96, 5, input, &nonce, &indices));
assert!(is_valid_solution(200, 9, input, &nonce, &indices));
is_valid_solution(96, 5, input, &nonce, &indices).unwrap_err();
is_valid_solution(200, 9, input, &nonce, &indices).unwrap();
nonce[0] = 1;
assert!(!is_valid_solution(96, 5, input, &nonce, &indices));
assert!(!is_valid_solution(200, 9, input, &nonce, &indices));
is_valid_solution(96, 5, input, &nonce, &indices).unwrap_err();
is_valid_solution(200, 9, input, &nonce, &indices).unwrap_err();
indices = vec![
1911, 96020, 94086, 96830, 7895, 51522, 56142, 62444, 15441, 100732, 48983, 64776,
27781, 85932, 101138, 114362, 4497, 14199, 36249, 41817, 23995, 93888, 35798, 96337,
5530, 82377, 66438, 85247, 39332, 78978, 83015, 123505,
];
assert!(is_valid_solution(96, 5, input, &nonce, &indices));
is_valid_solution(96, 5, input, &nonce, &indices).unwrap();
indices = vec![
1505, 1380774, 200806, 1787044, 101056, 1697952, 281464, 374899, 263712, 1532496,
@ -455,8 +512,8 @@ mod tests {
1644978, 278248, 2024807, 297914, 419798, 555747, 712605, 1012424, 1428921, 890113,
1822645, 1082368, 1392894,
];
assert!(!is_valid_solution(96, 5, input, &nonce, &indices));
assert!(is_valid_solution(200, 9, input, &nonce, &indices));
is_valid_solution(96, 5, input, &nonce, &indices).unwrap_err();
is_valid_solution(200, 9, input, &nonce, &indices).unwrap();
let input2 = b"Equihash is an asymmetric PoW based on the Generalised Birthday problem.";
indices = vec![
@ -464,6 +521,6 @@ mod tests {
45858, 116805, 92842, 111026, 15972, 115059, 85191, 90330, 68190, 122819, 81830, 91132,
23460, 49807, 52426, 80391, 69567, 114474, 104973, 122568,
];
assert!(is_valid_solution(96, 5, input2, &nonce, &indices));
is_valid_solution(96, 5, input2, &nonce, &indices).unwrap();
}
}

1
zcash_primitives/Cargo.toml
View File

@ -17,6 +17,7 @@ blake2b_simd = "0.5"
blake2s_simd = "0.5"
byteorder = "1"
crypto_api_chachapoly = "0.2.1"
equihash = { version = "0.1", path = "../components/equihash" }
ff = { version = "0.6", path = "../ff" }
fpe = "0.2"
hex = "0.3"

2
zcash_primitives/src/block.rs
View File

@ -9,7 +9,7 @@ use std::ops::Deref;
use crate::serialize::Vector;
pub mod equihash;
pub use equihash;
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct BlockHash(pub [u8; 32]);