104 lines
2.3 KiB
Go
104 lines
2.3 KiB
Go
package proofs
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import (
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"sort"
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"github.com/tendermint/tendermint/crypto/merkle"
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"github.com/tendermint/tendermint/libs/rand"
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)
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// SimpleResult contains a merkle.SimpleProof along with all data needed to build the confio/proof
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type SimpleResult struct {
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Key []byte
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Value []byte
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Proof *merkle.SimpleProof
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RootHash []byte
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}
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// GenerateRangeProof makes a tree of size and returns a range proof for one random element
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//
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// returns a range proof and the root hash of the tree
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func GenerateRangeProof(size int, loc Where) *SimpleResult {
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data := BuildMap(size)
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root, proofs, allkeys := merkle.SimpleProofsFromMap(data)
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key := GetKey(allkeys, loc)
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proof := proofs[key]
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res := &SimpleResult{
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Key: []byte(key),
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Value: toValue(key),
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Proof: proof,
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RootHash: root,
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}
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return res
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}
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// Where selects a location for a key - Left, Right, or Middle
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type Where int
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const (
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Left Where = iota
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Right
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Middle
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)
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func SortedKeys(data map[string][]byte) []string {
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keys := make([]string, len(data))
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i := 0
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for k := range data {
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keys[i] = k
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i++
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}
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sort.Strings(keys)
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return keys
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}
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func CalcRoot(data map[string][]byte) []byte {
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root, _, _ := merkle.SimpleProofsFromMap(data)
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return root
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}
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// GetKey this returns a key, on Left/Right/Middle
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func GetKey(allkeys []string, loc Where) string {
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if loc == Left {
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return allkeys[0]
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}
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if loc == Right {
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return allkeys[len(allkeys)-1]
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}
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// select a random index between 1 and allkeys-2
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idx := rand.Int()%(len(allkeys)-2) + 1
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return allkeys[idx]
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}
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// GetNonKey returns a missing key - Left of all, Right of all, or in the Middle
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func GetNonKey(allkeys []string, loc Where) string {
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if loc == Left {
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return string([]byte{1, 1, 1, 1})
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}
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if loc == Right {
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return string([]byte{0xff, 0xff, 0xff, 0xff})
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}
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// otherwise, next to an existing key (copy before mod)
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key := GetKey(allkeys, loc)
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key = key[:len(key)-2] + string([]byte{255, 255})
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return key
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}
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func toValue(key string) []byte {
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return []byte("value_for_" + key)
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}
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// BuildMap creates random key/values and stores in a map,
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// returns a list of all keys in sorted order
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func BuildMap(size int) map[string][]byte {
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data := make(map[string][]byte)
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// insert lots of info and store the bytes
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for i := 0; i < size; i++ {
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key := rand.Str(20)
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data[key] = toValue(key)
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}
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return data
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}
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