You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
173 lines
4.2 KiB
173 lines
4.2 KiB
/*
|
|
Computes a deterministic minimal height merkle tree hash.
|
|
If the number of items is not a power of two, some leaves
|
|
will be at different levels. Tries to keep both sides of
|
|
the tree the same size, but the left may be one greater.
|
|
|
|
Use this for short deterministic trees, such as the validator list.
|
|
For larger datasets, use IAVLTree.
|
|
|
|
*
|
|
/ \
|
|
/ \
|
|
/ \
|
|
/ \
|
|
* *
|
|
/ \ / \
|
|
/ \ / \
|
|
/ \ / \
|
|
* * * h6
|
|
/ \ / \ / \
|
|
h0 h1 h2 h3 h4 h5
|
|
|
|
*/
|
|
|
|
package merkle
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto/sha256"
|
|
|
|
"github.com/tendermint/tendermint/binary"
|
|
)
|
|
|
|
func HashFromTwoHashes(left []byte, right []byte) []byte {
|
|
var n int64
|
|
var err error
|
|
var hasher = sha256.New()
|
|
binary.WriteByteSlice(left, hasher, &n, &err)
|
|
binary.WriteByteSlice(right, hasher, &n, &err)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
return hasher.Sum(nil)
|
|
}
|
|
|
|
func HashFromHashes(hashes [][]byte) []byte {
|
|
// Recursive impl.
|
|
switch len(hashes) {
|
|
case 0:
|
|
return nil
|
|
case 1:
|
|
return hashes[0]
|
|
default:
|
|
left := HashFromHashes(hashes[:(len(hashes)+1)/2])
|
|
right := HashFromHashes(hashes[(len(hashes)+1)/2:])
|
|
return HashFromTwoHashes(left, right)
|
|
}
|
|
}
|
|
|
|
// Convenience for HashFromHashes.
|
|
func HashFromBinaries(items []interface{}) []byte {
|
|
hashes := [][]byte{}
|
|
for _, item := range items {
|
|
hasher, n, err := sha256.New(), new(int64), new(error)
|
|
binary.WriteBinary(item, hasher, n, err)
|
|
if *err != nil {
|
|
panic(err)
|
|
}
|
|
hashes = append(hashes, hasher.Sum(nil))
|
|
}
|
|
return HashFromHashes(hashes)
|
|
}
|
|
|
|
// Convenience for HashFromHashes.
|
|
func HashFromHashables(items []Hashable) []byte {
|
|
hashes := [][]byte{}
|
|
for _, item := range items {
|
|
hash := item.Hash()
|
|
hashes = append(hashes, hash)
|
|
}
|
|
return HashFromHashes(hashes)
|
|
}
|
|
|
|
type HashTrail struct {
|
|
Hash []byte
|
|
Parent *HashTrail
|
|
Left *HashTrail
|
|
Right *HashTrail
|
|
}
|
|
|
|
func (ht *HashTrail) Flatten() [][]byte {
|
|
// Nonrecursive impl.
|
|
trail := [][]byte{}
|
|
for ht != nil {
|
|
if ht.Left != nil {
|
|
trail = append(trail, ht.Left.Hash)
|
|
} else if ht.Right != nil {
|
|
trail = append(trail, ht.Right.Hash)
|
|
} else {
|
|
break
|
|
}
|
|
ht = ht.Parent
|
|
}
|
|
return trail
|
|
}
|
|
|
|
// returned trails[0].Hash is the leaf hash.
|
|
// trails[0].Parent.Hash is the hash above that, etc.
|
|
func HashTrailsFromHashables(items []Hashable) (trails []*HashTrail, root *HashTrail) {
|
|
// Recursive impl.
|
|
switch len(items) {
|
|
case 0:
|
|
return nil, nil
|
|
case 1:
|
|
trail := &HashTrail{items[0].Hash(), nil, nil, nil}
|
|
return []*HashTrail{trail}, trail
|
|
default:
|
|
lefts, leftRoot := HashTrailsFromHashables(items[:(len(items)+1)/2])
|
|
rights, rightRoot := HashTrailsFromHashables(items[(len(items)+1)/2:])
|
|
rootHash := HashFromTwoHashes(leftRoot.Hash, rightRoot.Hash)
|
|
root := &HashTrail{rootHash, nil, nil, nil}
|
|
leftRoot.Parent = root
|
|
leftRoot.Right = rightRoot
|
|
rightRoot.Parent = root
|
|
rightRoot.Left = leftRoot
|
|
return append(lefts, rights...), root
|
|
}
|
|
}
|
|
|
|
// Ensures that leafHash is part of rootHash.
|
|
func VerifyHashTrail(index uint, total uint, leafHash []byte, trail [][]byte, rootHash []byte) bool {
|
|
computedRoot := ComputeRootFromTrail(index, total, leafHash, trail)
|
|
if computedRoot == nil {
|
|
return false
|
|
}
|
|
return bytes.Equal(computedRoot, rootHash)
|
|
}
|
|
|
|
// Use the leafHash and trail to get the root merkle hash.
|
|
// If the length of the trail slice isn't exactly correct, the result is nil.
|
|
func ComputeRootFromTrail(index uint, total uint, leafHash []byte, trail [][]byte) []byte {
|
|
// Recursive impl.
|
|
if index >= total {
|
|
return nil
|
|
}
|
|
switch total {
|
|
case 0:
|
|
panic("Cannot call ComputeRootFromTrail() with 0 total")
|
|
case 1:
|
|
if len(trail) != 0 {
|
|
return nil
|
|
}
|
|
return leafHash
|
|
default:
|
|
if len(trail) == 0 {
|
|
return nil
|
|
}
|
|
numLeft := (total + 1) / 2
|
|
if index < numLeft {
|
|
leftRoot := ComputeRootFromTrail(index, numLeft, leafHash, trail[:len(trail)-1])
|
|
if leftRoot == nil {
|
|
return nil
|
|
}
|
|
return HashFromTwoHashes(leftRoot, trail[len(trail)-1])
|
|
} else {
|
|
rightRoot := ComputeRootFromTrail(index-numLeft, total-numLeft, leafHash, trail[:len(trail)-1])
|
|
if rightRoot == nil {
|
|
return nil
|
|
}
|
|
return HashFromTwoHashes(trail[len(trail)-1], rightRoot)
|
|
}
|
|
}
|
|
}
|