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Move constants and utils to package, apply small fixes

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This commit is contained in:
Eduard S
2019-07-01 12:51:34 +02:00
parent 09c29da99e
commit 5b79ded540
10 changed files with 244 additions and 228 deletions
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62
poseidon/poseidon.go
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@@ -6,7 +6,9 @@ import (
"math/big"
"strconv"
_constants "github.com/iden3/go-iden3-crypto/constants"
"github.com/iden3/go-iden3-crypto/field"
"github.com/iden3/go-iden3-crypto/utils"
"golang.org/x/crypto/blake2b"
)
@@ -23,55 +25,35 @@ type constantsData struct {
m [][]*big.Int
}
// checkBigIntInField checks if given big.Int fits in a Field R element
func checkBigIntInField(a *big.Int, q *big.Int) bool {
if a.Cmp(q) != -1 {
return false
}
return true
}
// checkBigIntArrayInField checks if given big.Int fits in a Field R element
func checkBigIntArrayInField(arr []*big.Int, q *big.Int) bool {
for _, a := range arr {
if !checkBigIntInField(a, q) {
return false
}
}
return true
}
func generateConstantsData() constantsData {
var constants constantsData
r, ok := new(big.Int).SetString("21888242871839275222246405745257275088548364400416034343698204186575808495617", 10)
if !ok {
}
fqR := field.NewFq(r)
fqR := field.NewFq(_constants.Q)
constants.fqR = fqR
constants.c = getPseudoRandom(fqR, SEED+"_constants", big.NewInt(int64(NROUNDSF+NROUNDSP)))
constants.c = getPseudoRandom(fqR, SEED+"_constants", NROUNDSF+NROUNDSP)
constants.m = getMDS(fqR)
return constants
}
func getPseudoRandom(fqR field.Fq, seed string, n *big.Int) []*big.Int {
var res []*big.Int
hash := blake2b.Sum256([]byte(seed))
for big.NewInt(int64(len(res))).Cmp(n) == -1 { // res < n
newN := fqR.Affine(leByteArrayToBigInt(fqR, hash[:]))
res = append(res, newN)
hash = blake2b.Sum256(hash[:])
func leByteArrayToBigInt(b []byte) *big.Int {
res := big.NewInt(0)
for i := 0; i < len(b); i++ {
n := big.NewInt(int64(b[i]))
res = new(big.Int).Add(res, new(big.Int).Lsh(n, uint(i*8)))
}
return res
}
func leByteArrayToBigInt(fqR field.Fq, b []byte) *big.Int {
res := fqR.Zero()
for i := 0; i < len(b); i++ {
n := big.NewInt(int64(b[i]))
res = new(big.Int).Add(res, new(big.Int).Lsh(n, uint(i*8)))
func getPseudoRandom(fqR field.Fq, seed string, n int) []*big.Int {
var res []*big.Int
hash := blake2b.Sum256([]byte(seed))
for len(res) < n {
hashBigInt := new(big.Int)
newN := fqR.Affine(utils.SetBigIntFromLEBytes(hashBigInt, hash[:]))
// newN := fqR.Affine(leByteArrayToBigInt(hash[:]))
res = append(res, newN)
hash = blake2b.Sum256(hash[:])
}
return res
}
@@ -87,10 +69,10 @@ func nonceToString(n int) string {
// https://eprint.iacr.org/2019/458.pdf pag.8
func getMDS(fqR field.Fq) [][]*big.Int {
nonce := 0
cauchyMatrix := getPseudoRandom(fqR, SEED+"_matrix_"+nonceToString(nonce), big.NewInt(T*2))
cauchyMatrix := getPseudoRandom(fqR, SEED+"_matrix_"+nonceToString(nonce), T*2)
for !checkAllDifferent(cauchyMatrix) {
nonce += 1
cauchyMatrix = getPseudoRandom(fqR, SEED+"_matrix_"+nonceToString(nonce), big.NewInt(T*2))
cauchyMatrix = getPseudoRandom(fqR, SEED+"_matrix_"+nonceToString(nonce), T*2)
}
var m [][]*big.Int
for i := 0; i < T; i++ {
@@ -160,10 +142,10 @@ func mix(state []*big.Int, m [][]*big.Int) []*big.Int {
// Hash computes the Poseidon hash for the given inputs
func Hash(inp []*big.Int) (*big.Int, error) {
var state []*big.Int
if len(inp) < 0 || len(inp) > T {
if len(inp) == 0 || len(inp) > T {
return nil, errors.New("wrong inputs length")
}
if !checkBigIntArrayInField(inp, constants.fqR.Q) {
if !utils.CheckBigIntArrayInField(inp, constants.fqR.Q) {
return nil, errors.New("inputs values not inside Finite Field")
}