mirror of
https://github.com/kaspanet/kaspad.git
synced 2025-05-23 15:26:42 +00:00
05941a76e7
* Increase size of reachability cache * Change DomainHash to struct with unexported hashArray * Fixing compilation errors stemming from new DomainHash structure * Remove obsolete Read/WriteElement methods in appmessage * Fix all tests * Fix all tests * Add comments * A few renamings * go mod tidy
101 lines
3.4 KiB
Go
101 lines
3.4 KiB
Go
package merkle
|
|
|
|
import (
|
|
"math"
|
|
|
|
"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
|
|
"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
|
|
"github.com/kaspanet/kaspad/domain/consensus/utils/hashes"
|
|
)
|
|
|
|
// nextPowerOfTwo returns the next highest power of two from a given number if
|
|
// it is not already a power of two. This is a helper function used during the
|
|
// calculation of a merkle tree.
|
|
func nextPowerOfTwo(n int) int {
|
|
// Return the number if it's already a power of 2.
|
|
if n&(n-1) == 0 {
|
|
return n
|
|
}
|
|
|
|
// Figure out and return the next power of two.
|
|
exponent := uint(math.Log2(float64(n))) + 1
|
|
return 1 << exponent // 2^exponent
|
|
}
|
|
|
|
// hashMerkleBranches takes two hashes, treated as the left and right tree
|
|
// nodes, and returns the hash of their concatenation. This is a helper
|
|
// function used to aid in the generation of a merkle tree.
|
|
func hashMerkleBranches(left, right *externalapi.DomainHash) *externalapi.DomainHash {
|
|
// Concatenate the left and right nodes.
|
|
w := hashes.NewMerkleBranchHashWriter()
|
|
|
|
w.InfallibleWrite(left.ByteSlice())
|
|
w.InfallibleWrite(right.ByteSlice())
|
|
|
|
return w.Finalize()
|
|
}
|
|
|
|
// CalculateHashMerkleRoot calculates the merkle root of a tree consisted of the given transaction hashes.
|
|
// See `merkleRoot` for more info.
|
|
func CalculateHashMerkleRoot(transactions []*externalapi.DomainTransaction) *externalapi.DomainHash {
|
|
txHashes := make([]*externalapi.DomainHash, len(transactions))
|
|
for i, tx := range transactions {
|
|
txHashes[i] = consensushashing.TransactionHash(tx)
|
|
}
|
|
return merkleRoot(txHashes)
|
|
}
|
|
|
|
// CalculateIDMerkleRoot calculates the merkle root of a tree consisted of the given transaction IDs.
|
|
// See `merkleRoot` for more info.
|
|
func CalculateIDMerkleRoot(transactions []*externalapi.DomainTransaction) *externalapi.DomainHash {
|
|
if len(transactions) == 0 {
|
|
return &externalapi.DomainHash{}
|
|
}
|
|
|
|
txIDs := make([]*externalapi.DomainHash, len(transactions))
|
|
for i, tx := range transactions {
|
|
txIDs[i] = (*externalapi.DomainHash)(consensushashing.TransactionID(tx))
|
|
}
|
|
return merkleRoot(txIDs)
|
|
}
|
|
|
|
// merkleRoot creates a merkle tree from a slice of hashes, and returns its root.
|
|
func merkleRoot(hashes []*externalapi.DomainHash) *externalapi.DomainHash {
|
|
// Calculate how many entries are required to hold the binary merkle
|
|
// tree as a linear array and create an array of that size.
|
|
nextPoT := nextPowerOfTwo(len(hashes))
|
|
arraySize := nextPoT*2 - 1
|
|
merkles := make([]*externalapi.DomainHash, arraySize)
|
|
|
|
// Create the base transaction hashes and populate the array with them.
|
|
for i, hash := range hashes {
|
|
merkles[i] = hash
|
|
}
|
|
|
|
// Start the array offset after the last transaction and adjusted to the
|
|
// next power of two.
|
|
offset := nextPoT
|
|
for i := 0; i < arraySize-1; i += 2 {
|
|
switch {
|
|
// When there is no left child node, the parent is nil too.
|
|
case merkles[i] == nil:
|
|
merkles[offset] = nil
|
|
|
|
// When there is no right child, the parent is generated by
|
|
// hashing the concatenation of the left child with zeros.
|
|
case merkles[i+1] == nil:
|
|
newHash := hashMerkleBranches(merkles[i], &externalapi.DomainHash{})
|
|
merkles[offset] = newHash
|
|
|
|
// The normal case sets the parent node to the hash
|
|
// of the concatentation of the left and right children.
|
|
default:
|
|
newHash := hashMerkleBranches(merkles[i], merkles[i+1])
|
|
merkles[offset] = newHash
|
|
}
|
|
offset++
|
|
}
|
|
|
|
return merkles[len(merkles)-1]
|
|
}
|