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Orchard: update merkle_crh_orchard to use the appropriate l=10 bits, not 6

This commit is contained in:
Deirdre Connolly 2021-03-16 19:28:15 -04:00 committed by Deirdre Connolly
parent 1ff8874b8d
commit 87f65b8b01
1 changed files with 5 additions and 4 deletions
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9
zebra-chain/src/orchard/tree.rs
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@ -29,17 +29,18 @@ const MERKLE_DEPTH: usize = 32;
///
/// Used to hash incremental Merkle tree hash values for Orchard.
///
/// MerkleCRH^Orchard(layer, left, right) := SinsemillaHashToPoint(“Zcash_PH”, l || left || right),
/// MerkleCRH^Orchard(layer, left, right) := SinsemillaHash("z.cash:Orchard-MerkleCRH", l || left || right),
///
/// where l = I2LEBSP_6(MerkleDepth^Orchard − 1 − layer) and left, right, and
/// where l = I2LEBSP_10(MerkleDepth^Orchard − 1 − layer) and left, right, and
/// the output are all technically 255 bits (l_MerkleOrchard), not 256.
///
/// https://zips.z.cash/protocol/nu5.pdf#merklecrh
/// https://zips.z.cash/protocol/nu5.pdf#constants
fn merkle_crh_orchard(layer: u8, left: [u8; 32], right: [u8; 32]) -> [u8; 32] {
let mut s = bitvec![Lsb0, u8;];
// Prefix: l = I2LEBSP_6(MerkleDepth^Orchard − 1 − layer)
s.extend_from_slice(&layer.bits::<Lsb0>()[0..6]);
// Prefix: l = I2LEBSP_10(MerkleDepth^Orchard − 1 − layer)
s.extend_from_slice(&layer.bits::<Lsb0>()[0..10]);
s.extend_from_slice(&left.bits::<Lsb0>()[0..255]);
s.extend_from_slice(&right.bits::<Lsb0>()[0..255]);