forked from txaty/go-merkletree
-
Notifications
You must be signed in to change notification settings - Fork 0
/
level_cache.go
161 lines (138 loc) · 3.58 KB
/
level_cache.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
package merkletree
import (
"encoding/gob"
"os"
"sync"
)
type LevelCache struct {
// leafMap maps the data (converted to string) of each leaf node to its index in the Tree slice.
LeafMap map[string]int
// leafMapMu is a mutex that protects concurrent access to the leafMap.
leafMapMu sync.Mutex
// Nodes contains the Merkle Tree's internal node structure.
Nodes [][][]byte
// Start is the level of the cache Merkle Tree. leaf level is 0.
Start int
// Level is the Levels of the cache Merkle Tree.
Level int
}
// start range:[0, depth-1]
// level range:[1, depth]
func NewLevelCache(m *MerkleTree, start int, level int) (*LevelCache, error) {
if m == nil {
return nil, ErrMerkleTreeIsNil
}
if m.Depth <= start || start < 0 {
return nil, ErrLevelCacheStart
}
if m.Depth < level || level < 1 {
return nil, ErrLevelCacheLevel
}
lc := LevelCache{Start: start, Level: level}
finishMap := make(chan struct{})
lc.LeafMap = make(map[string]int)
go func() {
lc.leafMapMu.Lock()
defer lc.leafMapMu.Unlock()
for i := 0; i < m.NumLeaves>>start; i++ {
lc.LeafMap[string(m.nodes[start][i])] = i
}
finishMap <- struct{}{} // empty channel to serve as a wait group for map generation
}()
lc.Nodes = make([][][]byte, level)
for i := 0; i < level; i++ {
lc.Nodes[i] = append(lc.Nodes[i], m.nodes[start+i]...)
}
<-finishMap
return &lc, nil
}
func NewLevelCacheFromFile(filePath string) (*LevelCache, error) {
readFile, err := os.Open(filePath)
if err != nil {
return nil, err
}
defer readFile.Close()
decoder := gob.NewDecoder(readFile)
loaded := LevelCache{}
if err = decoder.Decode(&loaded); err != nil {
return nil, err
}
return &loaded, nil
}
// Append sub tree Proof to base tree Proof
func AppendProof(base *Proof, sub Proof) (*Proof, error) {
base.Path += sub.Path
base.Siblings = append(base.Siblings, sub.Siblings...)
return base, nil
}
func (lc *LevelCache) StoreToFile(filePath string) error {
file, err := os.Create(filePath)
if err != nil {
return err
}
defer file.Close()
encoder := gob.NewEncoder(file)
if err = encoder.Encode(lc); err != nil {
return err
}
return nil
}
func (lc *LevelCache) Prove(dataBlock DataBlock, config *Config) (*Proof, []byte, error) {
leaf, err := dataBlockToLeaf(dataBlock, config)
if err != nil {
return nil, nil, err
}
// Retrieve the index of the leaf in the Merkle Tree.
lc.leafMapMu.Lock()
idx, ok := lc.LeafMap[string(leaf)]
lc.leafMapMu.Unlock()
if !ok {
return nil, nil, ErrProofInvalidDataBlock
}
// Compute the path and siblings for the proof.
var (
path uint32
siblings = make([][]byte, lc.Level)
)
for i := 0; i < lc.Level; i++ {
if idx&1 == 1 {
siblings[i] = lc.Nodes[i][idx-1]
} else {
// Absolute path
path += 1 << (i + lc.Start)
siblings[i] = lc.Nodes[i][idx+1]
}
idx >>= 1
}
if config == nil {
config = new(Config)
}
if config.HashFunc == nil {
config.HashFunc = DefaultHashFunc
}
// Determine the concatenation function based on the configuration.
concatFunc := concatHash
if config.SortSiblingPairs {
concatFunc = concatSortHash
}
// Traverse the Merkle proof and compute the root hash.
// Copy the slice so that the original leaf won't be modified.
root := make([]byte, len(leaf))
copy(root, leaf)
relativePath := path >> lc.Start
for _, sib := range siblings {
if relativePath&1 == 1 {
root, err = config.HashFunc(concatFunc(root, sib))
} else {
root, err = config.HashFunc(concatFunc(sib, root))
}
if err != nil {
return nil, nil, err
}
relativePath >>= 1
}
return &Proof{
Path: path,
Siblings: siblings,
}, root, nil
}