74 lines
1.9 KiB
Rust
74 lines
1.9 KiB
Rust
use hash::{H256, H512};
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use zebra_crypto::dhash256;
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#[inline]
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fn concat<T>(a: T, b: T) -> H512
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where
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T: AsRef<H256>,
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{
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let mut result = H512::default();
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result[0..32].copy_from_slice(&**a.as_ref());
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result[32..64].copy_from_slice(&**b.as_ref());
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result
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}
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/// Calculates the root of the merkle tree
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/// https://en.bitcoin.it/wiki/Protocol_documentation#Merkle_Trees
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pub fn merkle_root<T>(hashes: &[T]) -> H256
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where
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T: AsRef<H256>,
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{
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if hashes.len() == 1 {
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return hashes[0].as_ref().clone();
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}
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let mut row = Vec::with_capacity(hashes.len() / 2);
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let mut i = 0;
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while i + 1 < hashes.len() {
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row.push(merkle_node_hash(&hashes[i], &hashes[i + 1]));
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i += 2
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}
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// duplicate the last element if len is not even
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if hashes.len() % 2 == 1 {
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let last = &hashes[hashes.len() - 1];
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row.push(merkle_node_hash(last, last));
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}
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merkle_root(&row)
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}
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/// Calculate merkle tree node hash
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pub fn merkle_node_hash<T>(left: T, right: T) -> H256
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where
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T: AsRef<H256>,
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{
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dhash256(&*concat(left, right))
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}
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#[cfg(test)]
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mod tests {
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use super::merkle_root;
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use hash::H256;
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// block 80_000
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// https://blockchain.info/block/000000000043a8c0fd1d6f726790caa2a406010d19efd2780db27bdbbd93baf6
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#[test]
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fn test_merkle_root_with_2_hashes() {
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let tx1 = H256::from_reversed_str(
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"c06fbab289f723c6261d3030ddb6be121f7d2508d77862bb1e484f5cd7f92b25",
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);
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let tx2 = H256::from_reversed_str(
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"5a4ebf66822b0b2d56bd9dc64ece0bc38ee7844a23ff1d7320a88c5fdb2ad3e2",
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);
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let expected = H256::from_reversed_str(
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"8fb300e3fdb6f30a4c67233b997f99fdd518b968b9a3fd65857bfe78b2600719",
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);
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let result = merkle_root(&[&tx1, &tx2]);
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let result2 = merkle_root(&[tx1, tx2]);
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assert_eq!(result, expected);
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assert_eq!(result2, expected);
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}
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}
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