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rsa.go
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rsa.go
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package action
import (
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"errors"
"io"
"math/big"
"yulong-hids/server/models"
)
var bigZero = big.NewInt(0)
var bigOne = big.NewInt(1)
//采用私钥加密,公钥解密的方式传输
func priKeyEncrypt(rand io.Reader, priv *rsa.PrivateKey, hashed []byte) ([]byte, error) {
tLen := len(hashed)
k := (priv.N.BitLen() + 7) / 8
if k < tLen+11 {
return nil, errors.New("data length error")
}
em := make([]byte, k)
em[1] = 1
for i := 2; i < k-tLen-1; i++ {
em[i] = 0xff
}
copy(em[k-tLen:k], hashed)
m := new(big.Int).SetBytes(em)
c, err := decrypt(rand, priv, m)
if err != nil {
return nil, err
}
copyWithLeftPad(em, c.Bytes())
return em, nil
}
func encrypt(c *big.Int, pub *rsa.PublicKey, m *big.Int) *big.Int {
e := big.NewInt(int64(pub.E))
c.Exp(m, e, pub.N)
return c
}
func decrypt(random io.Reader, priv *rsa.PrivateKey, c *big.Int) (m *big.Int, err error) {
if c.Cmp(priv.N) > 0 {
err = errors.New("decryption error")
return
}
var ir *big.Int
if random != nil {
var r *big.Int
for {
r, err = rand.Int(random, priv.N)
if err != nil {
return
}
if r.Cmp(bigZero) == 0 {
r = bigOne
}
var ok bool
ir, ok = modInverse(r, priv.N)
if ok {
break
}
}
bigE := big.NewInt(int64(priv.E))
rpowe := new(big.Int).Exp(r, bigE, priv.N)
cCopy := new(big.Int).Set(c)
cCopy.Mul(cCopy, rpowe)
cCopy.Mod(cCopy, priv.N)
c = cCopy
}
if priv.Precomputed.Dp == nil {
m = new(big.Int).Exp(c, priv.D, priv.N)
} else {
m = new(big.Int).Exp(c, priv.Precomputed.Dp, priv.Primes[0])
m2 := new(big.Int).Exp(c, priv.Precomputed.Dq, priv.Primes[1])
m.Sub(m, m2)
if m.Sign() < 0 {
m.Add(m, priv.Primes[0])
}
m.Mul(m, priv.Precomputed.Qinv)
m.Mod(m, priv.Primes[0])
m.Mul(m, priv.Primes[1])
m.Add(m, m2)
for i, values := range priv.Precomputed.CRTValues {
prime := priv.Primes[2+i]
m2.Exp(c, values.Exp, prime)
m2.Sub(m2, m)
m2.Mul(m2, values.Coeff)
m2.Mod(m2, prime)
if m2.Sign() < 0 {
m2.Add(m2, prime)
}
m2.Mul(m2, values.R)
m.Add(m, m2)
}
}
if ir != nil {
m.Mul(m, ir)
m.Mod(m, priv.N)
}
return
}
func copyWithLeftPad(dest, src []byte) {
numPaddingBytes := len(dest) - len(src)
for i := 0; i < numPaddingBytes; i++ {
dest[i] = 0
}
copy(dest[numPaddingBytes:], src)
}
func modInverse(a, n *big.Int) (ia *big.Int, ok bool) {
g := new(big.Int)
x := new(big.Int)
y := new(big.Int)
g.GCD(x, y, a, n)
if g.Cmp(bigOne) != 0 {
return
}
if x.Cmp(bigOne) < 0 {
x.Add(x, n)
}
return x, true
}
func rsaEncrypt(origData []byte) ([]byte, error) {
block, _ := pem.Decode([]byte(models.Config.Private))
if block == nil {
return nil, errors.New("public key error")
}
pri, err := x509.ParsePKCS1PrivateKey(block.Bytes)
if err != nil {
return nil, err
}
return priKeyEncrypt(rand.Reader, pri, origData)
}