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husobee/lw16.go

Created Nov 8, 2018
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package main
import (
"crypto/hmac"
"crypto/rand"
"crypto/sha1"
"fmt"
"math/big"
)
var (
n = []byte{
1,
3,
10,
20,
62,
95,
}
nPi = map[byte]byte{
1: 3,
3: 10,
10: 20,
20: 62,
62: 95,
95: 1,
}
piN = map[byte]byte{
3: 1,
10: 3,
20: 10,
62: 20,
95: 62,
1: 95,
}
)
func cmp(x, y int) int {
if x > y {
return 1
}
if x < y {
return -1
}
return 0
}
func hash(input []byte) []byte {
sha := sha1.New()
sha.Write(input)
return sha.Sum(nil)
}
func prf(secret, input []byte) []byte {
mac := hmac.New(sha1.New, secret)
mac.Write(input)
return mac.Sum(nil)
}
func main() {
fmt.Println("Example LW 2016 Implementation")
ctr := [][]byte{}
ctl := [][]byte{}
var secret = []byte("secret")
for _, vv := range n {
// encrypt left value 1
var nonce = make([]byte, 1)
rand.Read(nonce)
encLeft := prf(secret, append([]byte{}, nPi[vv]))
var encRight = []byte{nonce[0]}
for _, v := range n {
var vi = big.NewInt(int64(cmp(int(v), int(vv))))
//fmt.Println(vi)
var tmp = big.NewInt(0)
tmp.SetBytes(hash(
append(
prf(secret, append([]byte{}, nPi[v])),
nonce[0])))
vi = vi.Add(vi, tmp)
vi = vi.Mod(vi, big.NewInt(3))
switch vi.Int64() {
case 0:
encRight = append(encRight, byte(0))
case 1:
encRight = append(encRight, byte(1))
case 2:
encRight = append(encRight, byte(2))
}
}
ctl = append(ctl, encLeft)
ctr = append(ctr, encRight)
}
// lets now do some compares!
// take ctr[0] and compare to ctl[0] should equal
left := ctl[0]
right := ctr[0]
fmt.Println("left: ", left)
fmt.Println("right: ", right)
vh := big.NewInt(int64(right[1]))
h := big.NewInt(0)
h.SetBytes(hash(append(left, right[0])))
v := vh.Sub(vh, h)
v = v.Mod(v, big.NewInt(3))
fmt.Println("compare result for N[0] to N[0] is ", v)
// take ctr[1] and compare to ctl[0] should greater than
left = ctl[0]
right = ctr[1]
fmt.Println("left: ", left)
fmt.Println("right: ", right)
vh = big.NewInt(int64(right[1]))
h = big.NewInt(0)
h.SetBytes(hash(append(left, right[0])))
v = vh.Sub(vh, h)
v = v.Mod(v, big.NewInt(3))
fmt.Println("compare result for N[1] to N[0] is ", v)
}
@husobee

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@husobee husobee commented Nov 8, 2018

left:  [153 21 131 191 226 95 111 244 83 235 40 167 84 167 91 112 196 118 99 15]
right:  [208 2 2 1 1 2 0]
compare result for N[0] to N[0] is  0
left:  [153 21 131 191 226 95 111 244 83 235 40 167 84 167 91 112 196 118 99 15]
right:  [57 2 1 1 1 1 2]
compare result for N[1] to N[0] is  2```
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