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chore(merkle_root): move function into lib.rs

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Signed-off-by: Johns Beharry <johns@peakshift.com>
This commit is contained in:
Johns Beharry 2019-02-27 04:51:23 -04:00
parent 5f9e93d338
commit 9fbacbf967
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GPG Key ID: EC114974742E2178
2 changed files with 59 additions and 41 deletions
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59
eth2/utils/hashing/src/lib.rs
View File

@ -8,6 +8,33 @@ pub fn hash(input: &[u8]) -> Vec<u8> {
result
}
/// Generate Merkle Root
///
/// Outputs a `Vec<u8>` byte array of the merkle root given a set of leaf node values.
/// Expects leaf nodes to already be hashed.
pub fn merkle_root(values: &[Vec<u8>]) -> Vec<u8> {
let values_len = values.len();
// vector to store hashes
// filled with 0 as placeholders
let mut o: Vec<Vec<u8>> = vec![vec![0]; values_len];
// append values to the end
o.append(&mut values.to_vec());
// traverse backwards as values are at the end
// then fill placeholders with a hash of two leaf nodes
for i in (0..values_len).rev() {
let mut current_value: Vec<u8> = o[i * 2].clone();
current_value.append(&mut o[i * 2 + 1].clone());
o[i] = hash(&current_value[..]);
}
// the root hash will be at index 1
o[1].clone()
}
#[cfg(test)]
mod tests {
use super::*;
@ -25,4 +52,36 @@ mod tests {
];
assert_eq!(expected, output.as_slice());
}
#[test]
fn test_merkle_root() {
// hash the leaf nodes
let mut input = vec![
hash("a".as_bytes()),
hash("b".as_bytes()),
hash("c".as_bytes()),
hash("d".as_bytes()),
];
// generate a merkle tree and return the root
let output = merkle_root(&input[..]);
// create merkle root manually
let mut leaf_1_2: Vec<u8> = input[0].clone(); // a
leaf_1_2.append(&mut input[1].clone()); // b
let mut leaf_3_4: Vec<u8> = input[2].clone(); // c
leaf_3_4.append(&mut input[3].clone()); // d
let node_1 = hash(&leaf_1_2[..]);
let node_2 = hash(&leaf_3_4[..]);
let mut root: Vec<u8> = node_1.clone(); // ab
root.append(&mut node_2.clone()); // cd
let expected = hash(&root[..]);
assert_eq!(&expected[..], output.as_slice());
}
}

41
eth2/utils/hashing/src/merkle_root.rs
View File

@ -1,41 +0,0 @@
use crate::hash;
pub fn merkle_root(values: &[Vec<u8>]) -> Vec<u8> {
let values_len = values.len();
let mut o: Vec<Vec<u8>> = vec![vec![0]; values_len];
o.append(&mut values.to_vec());
for i in (0..values_len).rev() {
let mut current_value: Vec<u8> = o[i * 2].clone();
current_value.append(&mut o[i * 2 + 1].clone());
o[i] = hash(&current_value[..]);
}
o[1].clone()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_merkle_root() {
let input = vec![
"a".as_bytes().to_vec(),
"b".as_bytes().to_vec(),
"c".as_bytes().to_vec(),
"d".as_bytes().to_vec()
];
let output = merkle_root(&input[..]);
// merkle root of [[a],[b],[c],[d]]
let expected = &[
183, 91, 96, 122, 144, 174, 84, 92, 97, 156, 140, 192, 66, 221, 55, 229,
234, 48, 118, 7, 61, 207, 39, 125, 150, 32, 94, 90, 19, 88, 122, 163,
];
assert_eq!(expected, output.as_slice());
}
}