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package ownrsa
import (
"errors"
"fmt"
"math/big"
"math/rand"
"strconv"
"strings"
"time"
)
type RSAPublicKey struct {
E *big.Int `json:"e"`
N *big.Int `json:"n"`
}
type RSAPublicKeyString struct {
E string `json:"e"`
N string `json:"n"`
}
type RSAPrivateKey struct {
D *big.Int `json:"d"`
N *big.Int `json:"n"`
}
type RSA struct {
PubK RSAPublicKey
PrivK RSAPrivateKey
}
type PackRSA struct {
PubK string `json:"pubK"`
PrivK string `json:"privK"`
Date time.Time `json:"date"`
PubKSigned string `json:"pubKSigned"`
}
const maxPrime = 500
const minPrime = 100
func GenerateKeyPair() RSA {
rand.Seed(time.Now().Unix())
p := randPrime(minPrime, maxPrime)
q := randPrime(minPrime, maxPrime)
fmt.Print("p:")
fmt.Println(p)
fmt.Print("q:")
fmt.Println(q)
n := p * q
phi := (p - 1) * (q - 1)
e := 65537
var pubK RSAPublicKey
pubK.E = big.NewInt(int64(e))
pubK.N = big.NewInt(int64(n))
d := new(big.Int).ModInverse(big.NewInt(int64(e)), big.NewInt(int64(phi)))
var privK RSAPrivateKey
privK.D = d
privK.N = big.NewInt(int64(n))
var rsa RSA
rsa.PubK = pubK
rsa.PrivK = privK
return rsa
}
func Encrypt(m string, pubK RSAPublicKey) []int {
var c []int
mBytes := []byte(m)
for _, byte := range mBytes {
c = append(c, EncryptInt(int(byte), pubK))
}
return c
}
func Decrypt(c []int, privK RSAPrivateKey) string {
var m string
var mBytes []byte
for _, indC := range c {
mBytes = append(mBytes, byte(DecryptInt(indC, privK)))
}
m = string(mBytes)
return m
}
func EncryptBigInt(bigint *big.Int, pubK RSAPublicKey) *big.Int {
Me := new(big.Int).Exp(bigint, pubK.E, nil)
c := new(big.Int).Mod(Me, pubK.N)
return c
}
func DecryptBigInt(bigint *big.Int, privK RSAPrivateKey) *big.Int {
Cd := new(big.Int).Exp(bigint, privK.D, nil)
m := new(big.Int).Mod(Cd, privK.N)
return m
}
func EncryptInt(char int, pubK RSAPublicKey) int {
charBig := big.NewInt(int64(char))
Me := charBig.Exp(charBig, pubK.E, nil)
c := Me.Mod(Me, pubK.N)
return int(c.Int64())
}
func DecryptInt(val int, privK RSAPrivateKey) int {
valBig := big.NewInt(int64(val))
Cd := valBig.Exp(valBig, privK.D, nil)
m := Cd.Mod(Cd, privK.N)
return int(m.Int64())
}
func Blind(m []int, r int, pubK RSAPublicKey, privK RSAPrivateKey) []int {
var mBlinded []int
rBigInt := big.NewInt(int64(r))
for i := 0; i < len(m); i++ {
mBigInt := big.NewInt(int64(m[i]))
rE := new(big.Int).Exp(rBigInt, pubK.E, nil)
mrE := new(big.Int).Mul(mBigInt, rE)
mrEmodN := new(big.Int).Mod(mrE, privK.N)
mBlinded = append(mBlinded, int(mrEmodN.Int64()))
}
return mBlinded
}
func BlindSign(m []int, privK RSAPrivateKey) []int {
var r []int
for i := 0; i < len(m); i++ {
mBigInt := big.NewInt(int64(m[i]))
sigma := new(big.Int).Exp(mBigInt, privK.D, privK.N)
r = append(r, int(sigma.Int64()))
}
return r
}
func Unblind(blindsigned []int, r int, pubK RSAPublicKey) []int {
var mSigned []int
rBigInt := big.NewInt(int64(r))
for i := 0; i < len(blindsigned); i++ {
bsBigInt := big.NewInt(int64(blindsigned[i]))
//r1 := new(big.Int).Exp(rBigInt, big.NewInt(int64(-1)), nil)
r1 := new(big.Int).ModInverse(rBigInt, pubK.N)
bsr := new(big.Int).Mul(bsBigInt, r1)
sig := new(big.Int).Mod(bsr, pubK.N)
mSigned = append(mSigned, int(sig.Int64()))
}
return mSigned
}
func Verify(msg []int, mSigned []int, pubK RSAPublicKey) bool {
if len(msg) != len(mSigned) {
return false
}
var mSignedDecrypted []int
for _, ms := range mSigned {
msBig := big.NewInt(int64(ms))
//decrypt the mSigned with pubK
Cd := new(big.Int).Exp(msBig, pubK.E, nil)
m := new(big.Int).Mod(Cd, pubK.N)
mSignedDecrypted = append(mSignedDecrypted, int(m.Int64()))
}
fmt.Print("msg signed decrypted: ")
fmt.Println(mSignedDecrypted)
r := true
//check if the mSignedDecrypted == msg
for i := 0; i < len(msg); i++ {
if msg[i] != mSignedDecrypted[i] {
r = false
}
}
return r
}
func HomomorphicMultiplication(c1 int, c2 int, pubK RSAPublicKey) int {
c1BigInt := big.NewInt(int64(c1))
c2BigInt := big.NewInt(int64(c2))
c1c2 := new(big.Int).Mul(c1BigInt, c2BigInt)
n2 := new(big.Int).Mul(pubK.N, pubK.N)
d := new(big.Int).Mod(c1c2, n2)
r := int(d.Int64())
return r
}
func PubKStringToBigInt(kS RSAPublicKeyString) (RSAPublicKey, error) {
var k RSAPublicKey
var ok bool
k.E, ok = new(big.Int).SetString(kS.E, 10)
if !ok {
return k, errors.New("error parsing big int E")
}
k.N, ok = new(big.Int).SetString(kS.N, 10)
if !ok {
return k, errors.New("error parsing big int N")
}
return k, nil
}
func PackKey(k RSA) PackRSA {
var p PackRSA
p.PubK = k.PubK.E.String() + "," + k.PubK.N.String()
p.PrivK = k.PrivK.D.String() + "," + k.PrivK.N.String()
return p
}
func UnpackKey(p PackRSA) RSA {
var k RSA
var ok bool
k.PubK.E, ok = new(big.Int).SetString(strings.Split(p.PubK, ",")[0], 10)
k.PubK.N, ok = new(big.Int).SetString(strings.Split(p.PubK, ",")[1], 10)
k.PrivK.D, ok = new(big.Int).SetString(strings.Split(p.PrivK, ",")[0], 10)
k.PrivK.N, ok = new(big.Int).SetString(strings.Split(p.PrivK, ",")[1], 10)
if !ok {
fmt.Println("error on Unpacking Keys")
}
return k
}
func ArrayIntToString(a []int, delim string) string {
return strings.Trim(strings.Replace(fmt.Sprint(a), " ", delim, -1), "[]")
}
func StringToArrayInt(s string, delim string) []int {
var a []int
arrayString := strings.Split(s, delim)
for _, s := range arrayString {
i, err := strconv.Atoi(s)
if err != nil {
fmt.Println(err)
}
a = append(a, i)
}
return a
}