simple merkle tree
This commit is contained in:
parent
2f8551d3b6
commit
fd296811df
|
@ -0,0 +1,4 @@
|
|||
## Simple Merkle Tree
|
||||
|
||||
For smaller static data structures that don't require immutable snapshots or mutability;
|
||||
for instance the transactions and validation signatures of a block can be hashed using this simple merkle tree logic.
|
|
@ -0,0 +1,277 @@
|
|||
/*
|
||||
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"
|
||||
"fmt"
|
||||
"sort"
|
||||
|
||||
"golang.org/x/crypto/ripemd160"
|
||||
|
||||
. "github.com/tendermint/go-common"
|
||||
"github.com/tendermint/go-wire"
|
||||
)
|
||||
|
||||
func SimpleHashFromTwoHashes(left []byte, right []byte) []byte {
|
||||
var n int
|
||||
var err error
|
||||
var hasher = ripemd160.New()
|
||||
wire.WriteByteSlice(left, hasher, &n, &err)
|
||||
wire.WriteByteSlice(right, hasher, &n, &err)
|
||||
if err != nil {
|
||||
PanicCrisis(err)
|
||||
}
|
||||
return hasher.Sum(nil)
|
||||
}
|
||||
|
||||
func SimpleHashFromHashes(hashes [][]byte) []byte {
|
||||
// Recursive impl.
|
||||
switch len(hashes) {
|
||||
case 0:
|
||||
return nil
|
||||
case 1:
|
||||
return hashes[0]
|
||||
default:
|
||||
left := SimpleHashFromHashes(hashes[:(len(hashes)+1)/2])
|
||||
right := SimpleHashFromHashes(hashes[(len(hashes)+1)/2:])
|
||||
return SimpleHashFromTwoHashes(left, right)
|
||||
}
|
||||
}
|
||||
|
||||
// Convenience for SimpleHashFromHashes.
|
||||
func SimpleHashFromBinaries(items []interface{}) []byte {
|
||||
hashes := make([][]byte, len(items))
|
||||
for i, item := range items {
|
||||
hashes[i] = SimpleHashFromBinary(item)
|
||||
}
|
||||
return SimpleHashFromHashes(hashes)
|
||||
}
|
||||
|
||||
// General Convenience
|
||||
func SimpleHashFromBinary(item interface{}) []byte {
|
||||
hasher, n, err := ripemd160.New(), new(int), new(error)
|
||||
wire.WriteBinary(item, hasher, n, err)
|
||||
if *err != nil {
|
||||
PanicCrisis(err)
|
||||
}
|
||||
return hasher.Sum(nil)
|
||||
}
|
||||
|
||||
// Convenience for SimpleHashFromHashes.
|
||||
func SimpleHashFromHashables(items []Hashable) []byte {
|
||||
hashes := make([][]byte, len(items))
|
||||
for i, item := range items {
|
||||
hash := item.Hash()
|
||||
hashes[i] = hash
|
||||
}
|
||||
return SimpleHashFromHashes(hashes)
|
||||
}
|
||||
|
||||
// Convenience for SimpleHashFromHashes.
|
||||
func SimpleHashFromMap(m map[string]interface{}) []byte {
|
||||
kpPairsH := MakeSortedKVPairs(m)
|
||||
return SimpleHashFromHashables(kpPairsH)
|
||||
}
|
||||
|
||||
//--------------------------------------------------------------------------------
|
||||
|
||||
/* Convenience struct for key-value pairs.
|
||||
A list of KVPairs is hashed via `SimpleHashFromHashables`.
|
||||
NOTE: Each `Value` is encoded for hashing without extra type information,
|
||||
so the user is presumed to be aware of the Value types.
|
||||
*/
|
||||
type KVPair struct {
|
||||
Key string
|
||||
Value interface{}
|
||||
}
|
||||
|
||||
func (kv KVPair) Hash() []byte {
|
||||
hasher, n, err := ripemd160.New(), new(int), new(error)
|
||||
wire.WriteString(kv.Key, hasher, n, err)
|
||||
if kvH, ok := kv.Value.(Hashable); ok {
|
||||
wire.WriteByteSlice(kvH.Hash(), hasher, n, err)
|
||||
} else {
|
||||
wire.WriteBinary(kv.Value, hasher, n, err)
|
||||
}
|
||||
if *err != nil {
|
||||
PanicSanity(*err)
|
||||
}
|
||||
return hasher.Sum(nil)
|
||||
}
|
||||
|
||||
type KVPairs []KVPair
|
||||
|
||||
func (kvps KVPairs) Len() int { return len(kvps) }
|
||||
func (kvps KVPairs) Less(i, j int) bool { return kvps[i].Key < kvps[j].Key }
|
||||
func (kvps KVPairs) Swap(i, j int) { kvps[i], kvps[j] = kvps[j], kvps[i] }
|
||||
func (kvps KVPairs) Sort() { sort.Sort(kvps) }
|
||||
|
||||
func MakeSortedKVPairs(m map[string]interface{}) []Hashable {
|
||||
kvPairs := []KVPair{}
|
||||
for k, v := range m {
|
||||
kvPairs = append(kvPairs, KVPair{k, v})
|
||||
}
|
||||
KVPairs(kvPairs).Sort()
|
||||
kvPairsH := []Hashable{}
|
||||
for _, kvp := range kvPairs {
|
||||
kvPairsH = append(kvPairsH, kvp)
|
||||
}
|
||||
return kvPairsH
|
||||
}
|
||||
|
||||
//--------------------------------------------------------------------------------
|
||||
|
||||
type SimpleProof struct {
|
||||
Aunts [][]byte `json:"aunts"` // Hashes from leaf's sibling to a root's child.
|
||||
}
|
||||
|
||||
// proofs[0] is the proof for items[0].
|
||||
func SimpleProofsFromHashables(items []Hashable) (rootHash []byte, proofs []*SimpleProof) {
|
||||
trails, rootSPN := trailsFromHashables(items)
|
||||
rootHash = rootSPN.Hash
|
||||
proofs = make([]*SimpleProof, len(items))
|
||||
for i, trail := range trails {
|
||||
proofs[i] = &SimpleProof{
|
||||
Aunts: trail.FlattenAunts(),
|
||||
}
|
||||
}
|
||||
return
|
||||
}
|
||||
|
||||
// Verify that leafHash is a leaf hash of the simple-merkle-tree
|
||||
// which hashes to rootHash.
|
||||
func (sp *SimpleProof) Verify(index int, total int, leafHash []byte, rootHash []byte) bool {
|
||||
computedHash := computeHashFromAunts(index, total, leafHash, sp.Aunts)
|
||||
if computedHash == nil {
|
||||
return false
|
||||
}
|
||||
if !bytes.Equal(computedHash, rootHash) {
|
||||
return false
|
||||
}
|
||||
return true
|
||||
}
|
||||
|
||||
func (sp *SimpleProof) String() string {
|
||||
return sp.StringIndented("")
|
||||
}
|
||||
|
||||
func (sp *SimpleProof) StringIndented(indent string) string {
|
||||
return fmt.Sprintf(`SimpleProof{
|
||||
%s Aunts: %X
|
||||
%s}`,
|
||||
indent, sp.Aunts,
|
||||
indent)
|
||||
}
|
||||
|
||||
// Use the leafHash and innerHashes to get the root merkle hash.
|
||||
// If the length of the innerHashes slice isn't exactly correct, the result is nil.
|
||||
func computeHashFromAunts(index int, total int, leafHash []byte, innerHashes [][]byte) []byte {
|
||||
// Recursive impl.
|
||||
if index >= total {
|
||||
return nil
|
||||
}
|
||||
switch total {
|
||||
case 0:
|
||||
PanicSanity("Cannot call computeHashFromAunts() with 0 total")
|
||||
return nil
|
||||
case 1:
|
||||
if len(innerHashes) != 0 {
|
||||
return nil
|
||||
}
|
||||
return leafHash
|
||||
default:
|
||||
if len(innerHashes) == 0 {
|
||||
return nil
|
||||
}
|
||||
numLeft := (total + 1) / 2
|
||||
if index < numLeft {
|
||||
leftHash := computeHashFromAunts(index, numLeft, leafHash, innerHashes[:len(innerHashes)-1])
|
||||
if leftHash == nil {
|
||||
return nil
|
||||
}
|
||||
return SimpleHashFromTwoHashes(leftHash, innerHashes[len(innerHashes)-1])
|
||||
} else {
|
||||
rightHash := computeHashFromAunts(index-numLeft, total-numLeft, leafHash, innerHashes[:len(innerHashes)-1])
|
||||
if rightHash == nil {
|
||||
return nil
|
||||
}
|
||||
return SimpleHashFromTwoHashes(innerHashes[len(innerHashes)-1], rightHash)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Helper structure to construct merkle proof.
|
||||
// The node and the tree is thrown away afterwards.
|
||||
// Exactly one of node.Left and node.Right is nil, unless node is the root, in which case both are nil.
|
||||
// node.Parent.Hash = hash(node.Hash, node.Right.Hash) or
|
||||
// hash(node.Left.Hash, node.Hash), depending on whether node is a left/right child.
|
||||
type SimpleProofNode struct {
|
||||
Hash []byte
|
||||
Parent *SimpleProofNode
|
||||
Left *SimpleProofNode // Left sibling (only one of Left,Right is set)
|
||||
Right *SimpleProofNode // Right sibling (only one of Left,Right is set)
|
||||
}
|
||||
|
||||
// Starting from a leaf SimpleProofNode, FlattenAunts() will return
|
||||
// the inner hashes for the item corresponding to the leaf.
|
||||
func (spn *SimpleProofNode) FlattenAunts() [][]byte {
|
||||
// Nonrecursive impl.
|
||||
innerHashes := [][]byte{}
|
||||
for spn != nil {
|
||||
if spn.Left != nil {
|
||||
innerHashes = append(innerHashes, spn.Left.Hash)
|
||||
} else if spn.Right != nil {
|
||||
innerHashes = append(innerHashes, spn.Right.Hash)
|
||||
} else {
|
||||
break
|
||||
}
|
||||
spn = spn.Parent
|
||||
}
|
||||
return innerHashes
|
||||
}
|
||||
|
||||
// trails[0].Hash is the leaf hash for items[0].
|
||||
// trails[i].Parent.Parent....Parent == root for all i.
|
||||
func trailsFromHashables(items []Hashable) (trails []*SimpleProofNode, root *SimpleProofNode) {
|
||||
// Recursive impl.
|
||||
switch len(items) {
|
||||
case 0:
|
||||
return nil, nil
|
||||
case 1:
|
||||
trail := &SimpleProofNode{items[0].Hash(), nil, nil, nil}
|
||||
return []*SimpleProofNode{trail}, trail
|
||||
default:
|
||||
lefts, leftRoot := trailsFromHashables(items[:(len(items)+1)/2])
|
||||
rights, rightRoot := trailsFromHashables(items[(len(items)+1)/2:])
|
||||
rootHash := SimpleHashFromTwoHashes(leftRoot.Hash, rightRoot.Hash)
|
||||
root := &SimpleProofNode{rootHash, nil, nil, nil}
|
||||
leftRoot.Parent = root
|
||||
leftRoot.Right = rightRoot
|
||||
rightRoot.Parent = root
|
||||
rightRoot.Left = leftRoot
|
||||
return append(lefts, rights...), root
|
||||
}
|
||||
}
|
|
@ -0,0 +1,87 @@
|
|||
package merkle
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
|
||||
. "github.com/tendermint/go-common"
|
||||
. "github.com/tendermint/go-common/test"
|
||||
|
||||
"testing"
|
||||
)
|
||||
|
||||
type testItem []byte
|
||||
|
||||
func (tI testItem) Hash() []byte {
|
||||
return []byte(tI)
|
||||
}
|
||||
|
||||
func TestSimpleProof(t *testing.T) {
|
||||
|
||||
total := 100
|
||||
|
||||
items := make([]Hashable, total)
|
||||
for i := 0; i < total; i++ {
|
||||
items[i] = testItem(RandBytes(32))
|
||||
}
|
||||
|
||||
rootHash := SimpleHashFromHashables(items)
|
||||
|
||||
rootHash2, proofs := SimpleProofsFromHashables(items)
|
||||
|
||||
if !bytes.Equal(rootHash, rootHash2) {
|
||||
t.Errorf("Unmatched root hashes: %X vs %X", rootHash, rootHash2)
|
||||
}
|
||||
|
||||
// For each item, check the trail.
|
||||
for i, item := range items {
|
||||
itemHash := item.Hash()
|
||||
proof := proofs[i]
|
||||
|
||||
// Verify success
|
||||
ok := proof.Verify(i, total, itemHash, rootHash)
|
||||
if !ok {
|
||||
t.Errorf("Verification failed for index %v.", i)
|
||||
}
|
||||
|
||||
// Wrong item index should make it fail
|
||||
{
|
||||
ok = proof.Verify((i+1)%total, total, itemHash, rootHash)
|
||||
if ok {
|
||||
t.Errorf("Expected verification to fail for wrong index %v.", i)
|
||||
}
|
||||
}
|
||||
|
||||
// Trail too long should make it fail
|
||||
origAunts := proof.Aunts
|
||||
proof.Aunts = append(proof.Aunts, RandBytes(32))
|
||||
{
|
||||
ok = proof.Verify(i, total, itemHash, rootHash)
|
||||
if ok {
|
||||
t.Errorf("Expected verification to fail for wrong trail length.")
|
||||
}
|
||||
}
|
||||
proof.Aunts = origAunts
|
||||
|
||||
// Trail too short should make it fail
|
||||
proof.Aunts = proof.Aunts[0 : len(proof.Aunts)-1]
|
||||
{
|
||||
ok = proof.Verify(i, total, itemHash, rootHash)
|
||||
if ok {
|
||||
t.Errorf("Expected verification to fail for wrong trail length.")
|
||||
}
|
||||
}
|
||||
proof.Aunts = origAunts
|
||||
|
||||
// Mutating the itemHash should make it fail.
|
||||
ok = proof.Verify(i, total, MutateByteSlice(itemHash), rootHash)
|
||||
if ok {
|
||||
t.Errorf("Expected verification to fail for mutated leaf hash")
|
||||
}
|
||||
|
||||
// Mutating the rootHash should make it fail.
|
||||
ok = proof.Verify(i, total, itemHash, MutateByteSlice(rootHash))
|
||||
if ok {
|
||||
t.Errorf("Expected verification to fail for mutated root hash")
|
||||
}
|
||||
}
|
||||
}
|
|
@ -0,0 +1,23 @@
|
|||
package merkle
|
||||
|
||||
type Tree interface {
|
||||
Size() (size int)
|
||||
Height() (height int8)
|
||||
Has(key []byte) (has bool)
|
||||
Proof(key []byte) (value []byte, proof []byte, exists bool) // TODO make it return an index
|
||||
Get(key []byte) (index int, value []byte, exists bool)
|
||||
GetByIndex(index int) (key []byte, value []byte)
|
||||
Set(key []byte, value []byte) (updated bool)
|
||||
Remove(key []byte) (value []byte, removed bool)
|
||||
HashWithCount() (hash []byte, count int)
|
||||
Hash() (hash []byte)
|
||||
Save() (hash []byte)
|
||||
Load(hash []byte)
|
||||
Copy() Tree
|
||||
Iterate(func(key []byte, value []byte) (stop bool)) (stopped bool)
|
||||
IterateRange(start []byte, end []byte, ascending bool, fx func(key []byte, value []byte) (stop bool)) (stopped bool)
|
||||
}
|
||||
|
||||
type Hashable interface {
|
||||
Hash() []byte
|
||||
}
|
Loading…
Reference in New Issue