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.
198 lines
6.1 KiB
198 lines
6.1 KiB
package merkle
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
"fmt"
|
|
|
|
"github.com/tendermint/tendermint/crypto/tmhash"
|
|
cmn "github.com/tendermint/tendermint/libs/common"
|
|
)
|
|
|
|
// SimpleProof represents a simple Merkle proof.
|
|
// NOTE: The convention for proofs is to include leaf hashes but to
|
|
// exclude the root hash.
|
|
// This convention is implemented across IAVL range proofs as well.
|
|
// Keep this consistent unless there's a very good reason to change
|
|
// everything. This also affects the generalized proof system as
|
|
// well.
|
|
type SimpleProof struct {
|
|
Total int `json:"total"` // Total number of items.
|
|
Index int `json:"index"` // Index of item to prove.
|
|
LeafHash []byte `json:"leaf_hash"` // Hash of item value.
|
|
Aunts [][]byte `json:"aunts"` // Hashes from leaf's sibling to a root's child.
|
|
}
|
|
|
|
// SimpleProofsFromByteSlices computes inclusion proof for given items.
|
|
// proofs[0] is the proof for items[0].
|
|
func SimpleProofsFromByteSlices(items [][]byte) (rootHash []byte, proofs []*SimpleProof) {
|
|
trails, rootSPN := trailsFromByteSlices(items)
|
|
rootHash = rootSPN.Hash
|
|
proofs = make([]*SimpleProof, len(items))
|
|
for i, trail := range trails {
|
|
proofs[i] = &SimpleProof{
|
|
Total: len(items),
|
|
Index: i,
|
|
LeafHash: trail.Hash,
|
|
Aunts: trail.FlattenAunts(),
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// SimpleProofsFromMap generates proofs from a map. The keys/values of the map will be used as the keys/values
|
|
// in the underlying key-value pairs.
|
|
// The keys are sorted before the proofs are computed.
|
|
func SimpleProofsFromMap(m map[string][]byte) (rootHash []byte, proofs map[string]*SimpleProof, keys []string) {
|
|
sm := newSimpleMap()
|
|
for k, v := range m {
|
|
sm.Set(k, v)
|
|
}
|
|
sm.Sort()
|
|
kvs := sm.kvs
|
|
kvsBytes := make([][]byte, len(kvs))
|
|
for i, kvp := range kvs {
|
|
kvsBytes[i] = KVPair(kvp).Bytes()
|
|
}
|
|
|
|
rootHash, proofList := SimpleProofsFromByteSlices(kvsBytes)
|
|
proofs = make(map[string]*SimpleProof)
|
|
keys = make([]string, len(proofList))
|
|
for i, kvp := range kvs {
|
|
proofs[string(kvp.Key)] = proofList[i]
|
|
keys[i] = string(kvp.Key)
|
|
}
|
|
return
|
|
}
|
|
|
|
// Verify that the SimpleProof proves the root hash.
|
|
// Check sp.Index/sp.Total manually if needed
|
|
func (sp *SimpleProof) Verify(rootHash []byte, leafHash []byte) error {
|
|
if sp.Total < 0 {
|
|
return errors.New("Proof total must be positive")
|
|
}
|
|
if sp.Index < 0 {
|
|
return errors.New("Proof index cannot be negative")
|
|
}
|
|
if !bytes.Equal(sp.LeafHash, leafHash) {
|
|
return cmn.NewError("invalid leaf hash: wanted %X got %X", leafHash, sp.LeafHash)
|
|
}
|
|
computedHash := sp.ComputeRootHash()
|
|
if !bytes.Equal(computedHash, rootHash) {
|
|
return cmn.NewError("invalid root hash: wanted %X got %X", rootHash, computedHash)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Compute the root hash given a leaf hash. Does not verify the result.
|
|
func (sp *SimpleProof) ComputeRootHash() []byte {
|
|
return computeHashFromAunts(
|
|
sp.Index,
|
|
sp.Total,
|
|
sp.LeafHash,
|
|
sp.Aunts,
|
|
)
|
|
}
|
|
|
|
// String implements the stringer interface for SimpleProof.
|
|
// It is a wrapper around StringIndented.
|
|
func (sp *SimpleProof) String() string {
|
|
return sp.StringIndented("")
|
|
}
|
|
|
|
// StringIndented generates a canonical string representation of a SimpleProof.
|
|
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.
|
|
// Recursive impl.
|
|
func computeHashFromAunts(index int, total int, leafHash []byte, innerHashes [][]byte) []byte {
|
|
if index >= total || index < 0 || total <= 0 {
|
|
return nil
|
|
}
|
|
switch total {
|
|
case 0:
|
|
panic("Cannot call computeHashFromAunts() with 0 total")
|
|
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])
|
|
}
|
|
rightHash := computeHashFromAunts(index-numLeft, total-numLeft, leafHash, innerHashes[:len(innerHashes)-1])
|
|
if rightHash == nil {
|
|
return nil
|
|
}
|
|
return SimpleHashFromTwoHashes(innerHashes[len(innerHashes)-1], rightHash)
|
|
}
|
|
}
|
|
|
|
// SimpleProofNode is a 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)
|
|
}
|
|
|
|
// FlattenAunts will return the inner hashes for the item corresponding to the leaf,
|
|
// starting from a leaf SimpleProofNode.
|
|
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 trailsFromByteSlices(items [][]byte) (trails []*SimpleProofNode, root *SimpleProofNode) {
|
|
// Recursive impl.
|
|
switch len(items) {
|
|
case 0:
|
|
return nil, nil
|
|
case 1:
|
|
trail := &SimpleProofNode{tmhash.Sum(items[0]), nil, nil, nil}
|
|
return []*SimpleProofNode{trail}, trail
|
|
default:
|
|
lefts, leftRoot := trailsFromByteSlices(items[:(len(items)+1)/2])
|
|
rights, rightRoot := trailsFromByteSlices(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
|
|
}
|
|
}
|