sm2.go

/*
Copyright Suzhou Tongji Fintech Research Institute 2017 All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package sm2

// reference to ecdsa
import (
	"bytes"
	"crypto"
	"crypto/aes"
	"crypto/cipher"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/sha512"
	"encoding/asn1"
	"encoding/binary"
	"errors"
	"io"
	"math/big"
	//"fmt"
	"github.com/aiguo186/fabric-sdk-go-gm/internal/github.com/tjfoc/gmsm/sm3"
)

const (
	aesIV = "IV for <SM2> CTR"
)

type PublicKey struct {
	elliptic.Curve
	X, Y *big.Int
}

type PrivateKey struct {
	PublicKey
	D *big.Int
}

type sm2Signature struct {
	R, S *big.Int
}

// The SM2's private key contains the public key
func (priv *PrivateKey) Public() crypto.PublicKey {
	return &priv.PublicKey
}

func SignDigitToSignData(r, s *big.Int) ([]byte, error) {
	return asn1.Marshal(sm2Signature{r, s})
}

func SignDataToSignDigit(sign []byte) (*big.Int, *big.Int, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'SignDataToSignDigit' runing ")

	var sm2Sign sm2Signature

	_, err := asn1.Unmarshal(sign, &sm2Sign)
	if err != nil {
		return nil, nil, err
	}
	return sm2Sign.R, sm2Sign.S, nil
}

// sign format = 30 + len(z) + 02 + len(r) + r + 02 + len(s) + s, z being what follows its size, ie 02+len(r)+r+02+len(s)+s
func (priv *PrivateKey) Sign(rand io.Reader, msg []byte, opts crypto.SignerOpts) ([]byte, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Sign 1' runing ")
	//fmt.Println("wcx Debug:",priv.D.String())
	//fmt.Println("wcx Debug: ",msg)
	//fmt.Println("wcx Debug:",opts)

	r, s, err := Sign(rand,priv, msg)  //rand wcx add.我们自己国密代码中有rand
	if err != nil {
		return nil, err
	}
	t,err:= asn1.Marshal(sm2Signature{r, s})
	//fmt.Println("wcx Debug:t=",t)
	return t,err
}

func (priv *PrivateKey) Decrypt(data []byte) ([]byte, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Decrypt' runing ")

	return Decrypt(priv, data)
}

func (pub *PublicKey) Verify(msg []byte, sign []byte) bool {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Verify 1' runing ")

	var sm2Sign sm2Signature

	_, err := asn1.Unmarshal(sign, &sm2Sign)
	if err != nil {
		return false
	}
	return Verify(pub, msg, sm2Sign.R, sm2Sign.S)
}

func (pub *PublicKey) Encrypt(data []byte) ([]byte, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Encrypt' runing ")

	return Encrypt(pub, data)
}

var one = new(big.Int).SetInt64(1)

func intToBytes(x int) []byte {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'intToBytes' runing ")

	var buf = make([]byte, 4)

	binary.BigEndian.PutUint32(buf, uint32(x))
	return buf
}

func kdf(x, y []byte, length int) ([]byte, bool) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'kdf' runing ")

	var c []byte

	ct := 1
	h := sm3.New()
	x = append(x, y...)
	for i, j := 0, (length+31)/32; i < j; i++ {
		h.Reset()
		h.Write(x)
		h.Write(intToBytes(ct))
		hash := h.Sum(nil)
		if i+1 == j && length%32 != 0 {
			c = append(c, hash[:length%32]...)
		} else {
			c = append(c, hash...)
		}
		ct++
	}
	for i := 0; i < length; i++ {
		if c[i] != 0 {
			return c, true
		}
	}
	return c, false
}

func randFieldElement(c elliptic.Curve, rand io.Reader) (k *big.Int, err error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'randFieldElement' runing ")

	params := c.Params()
	b := make([]byte, params.BitSize/8+8)
	_, err = io.ReadFull(rand, b)
	if err != nil {
		return
	}
	k = new(big.Int).SetBytes(b)
	n := new(big.Int).Sub(params.N, one)
	k.Mod(k, n)
	k.Add(k, one)
	return
}

func GenerateKey() (*PrivateKey, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'GenerateKey' runing ")

	c := P256Sm2()
	k, err := randFieldElement(c, rand.Reader)
	if err != nil {
		return nil, err
	}
	priv := new(PrivateKey)
	priv.PublicKey.Curve = c
	priv.D = k
	priv.PublicKey.X, priv.PublicKey.Y = c.ScalarBaseMult(k.Bytes())
	return priv, nil
}

var errZeroParam = errors.New("zero parameter")

func Sign(rand io.Reader,priv *PrivateKey, hash []byte) (r, s *big.Int, err error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Sign 2' runing ")

	//fmt.Printf("comes hahahahahhahahah %s",hex.Dump(hash))
	entropylen := (priv.Curve.Params().BitSize + 7) / 16
	if entropylen > 32 {
		entropylen = 32
	}
	entropy := make([]byte, entropylen)
	_, err = io.ReadFull(rand, entropy)
	if err != nil {
		return
	}

	// Initialize an SHA-512 hash context; digest ...
	md := sha512.New()
	md.Write(priv.D.Bytes()) // the private key,
	md.Write(entropy)        // the entropy,
	md.Write(hash)           // and the input hash;
	key := md.Sum(nil)[:32]  // and compute ChopMD-256(SHA-512),
	// which is an indifferentiable MAC.

	// Create an AES-CTR instance to use as a CSPRNG.
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, nil, err
	}

	// Create a CSPRNG that xors a stream of zeros with
	// the output of the AES-CTR instance.
	csprng := cipher.StreamReader{
		R: zeroReader,
		S: cipher.NewCTR(block, []byte(aesIV)),
	}

	// See [NSA] 3.4.1
	c := priv.PublicKey.Curve
	N := c.Params().N
	if N.Sign() == 0 {
		return nil, nil, errZeroParam
	}
	var k *big.Int
	e := new(big.Int).SetBytes(hash)
	for { // 调整算法细节以实现SM2
		for {
			k, err = randFieldElement(c, csprng)
			if err != nil {
				r = nil
				return
			}
			r, _ = priv.Curve.ScalarBaseMult(k.Bytes())
			r.Add(r, e)
			r.Mod(r, N)
			if r.Sign() != 0 {
				break
			}
			if t := new(big.Int).Add(r, k); t.Cmp(N) == 0 {
				break
			}
		}
		rD := new(big.Int).Mul(priv.D, r)
		s = new(big.Int).Sub(k, rD)
		d1 := new(big.Int).Add(priv.D, one)
		d1Inv := new(big.Int).ModInverse(d1, N)
		s.Mul(s, d1Inv)
		s.Mod(s, N)
		if s.Sign() != 0 {
			break
		}
	}
	return
}

func Verify(pub *PublicKey, hash []byte, r, s *big.Int) bool {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Verify 2' runing ")

	c := pub.Curve
	N := c.Params().N

	if r.Sign() <= 0 || s.Sign() <= 0 {
		return false
	}
	if r.Cmp(N) >= 0 || s.Cmp(N) >= 0 {
		return false
	}

	// 调整算法细节以实现SM2
	t := new(big.Int).Add(r, s)
	t.Mod(t, N)
	if t.Sign() == 0 {
		return false
	}

	var x *big.Int
	x1, y1 := c.ScalarBaseMult(s.Bytes())
	x2, y2 := c.ScalarMult(pub.X, pub.Y, t.Bytes())
	x, _ = c.Add(x1, y1, x2, y2)

	e := new(big.Int).SetBytes(hash)
	x.Add(x, e)
	x.Mod(x, N)
	return x.Cmp(r) == 0
}

func Sm2Sign(priv *PrivateKey, msg, uid []byte) (r, s *big.Int, err error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Sm2Sign' runing ")

	za, err := ZA(&priv.PublicKey, uid)
	if err != nil {
		return nil, nil, err
	}
	e, err := msgHash(za, msg)
	if err != nil {
		return nil, nil, err
	}
	c := priv.PublicKey.Curve
	N := c.Params().N
	if N.Sign() == 0 {
		return nil, nil, errZeroParam
	}
	var k *big.Int
	for { // 调整算法细节以实现SM2
		for {
			k, err = randFieldElement(c, rand.Reader)
			if err != nil {
				r = nil
				return
			}
			r, _ = priv.Curve.ScalarBaseMult(k.Bytes())
			r.Add(r, e)
			r.Mod(r, N)
			if r.Sign() != 0 {
				break
			}
			if t := new(big.Int).Add(r, k); t.Cmp(N) == 0 {
				break
			}
		}
		rD := new(big.Int).Mul(priv.D, r)
		s = new(big.Int).Sub(k, rD)
		d1 := new(big.Int).Add(priv.D, one)
		d1Inv := new(big.Int).ModInverse(d1, N)
		s.Mul(s, d1Inv)
		s.Mod(s, N)
		if s.Sign() != 0 {
			break
		}
	}
	return
}

func Sm2Verify(pub *PublicKey, msg, uid []byte, r, s *big.Int) bool {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Sm2Verify' runing ")

	c := pub.Curve
	N := c.Params().N
	one := new(big.Int).SetInt64(1)
	if r.Cmp(one) < 0 || s.Cmp(one) < 0 {
		return false
	}
	if r.Cmp(N) >= 0 || s.Cmp(N) >= 0 {
		return false
	}
	za, err := ZA(pub, uid)
	if err != nil {
		return false
	}
	e, err := msgHash(za, msg)
	if err != nil {
		return false
	}
	t := new(big.Int).Add(r, s)
	t.Mod(t, N)
	if t.Sign() == 0 {
		return false
	}
	var x *big.Int
	x1, y1 := c.ScalarBaseMult(s.Bytes())
	x2, y2 := c.ScalarMult(pub.X, pub.Y, t.Bytes())
	x, _ = c.Add(x1, y1, x2, y2)

	x.Add(x, e)
	x.Mod(x, N)
	return x.Cmp(r) == 0
}

func msgHash(za, msg []byte) (*big.Int, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'msgHash' runing ")

	e := sm3.New()
	e.Write(za)
	e.Write(msg)
	return new(big.Int).SetBytes(e.Sum(nil)[:32]), nil
}

// ZA = H256(ENTLA || IDA || a || b || xG || yG || xA || yA)
func ZA(pub *PublicKey, uid []byte) ([]byte, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'ZA' runing ")

	za := sm3.New()
	uidLen := len(uid)
	if uidLen >= 8192 {
		return []byte{}, errors.New("SM2: uid too large")
	}
	Entla := uint16(8 * uidLen)
	za.Write([]byte{byte((Entla >> 8) & 0xFF)})
	za.Write([]byte{byte(Entla & 0xFF)})
	za.Write(uid)
	za.Write(sm2P256ToBig(&sm2P256.a).Bytes())
	za.Write(sm2P256.B.Bytes())
	za.Write(sm2P256.Gx.Bytes())
	za.Write(sm2P256.Gy.Bytes())

	xBuf := pub.X.Bytes()
	yBuf := pub.Y.Bytes()
	if n := len(xBuf); n < 32 {
		xBuf = append(zeroByteSlice()[:32-n], xBuf...)
	}
	za.Write(xBuf)
	za.Write(yBuf)
	return za.Sum(nil)[:32], nil
}

// 32byte
func zeroByteSlice() []byte {
	return []byte{
		0, 0, 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 0,
	}
}

/*
 * sm2密文结构如下:
 *  x
 *  y
 *  hash
 *  CipherText
 */
func Encrypt(pub *PublicKey, data []byte) ([]byte, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Encrypt 2' runing ")

	length := len(data)
	for {
		c := []byte{}
		curve := pub.Curve
		k, err := randFieldElement(curve, rand.Reader)
		if err != nil {
			return nil, err
		}
		x1, y1 := curve.ScalarBaseMult(k.Bytes())
		x2, y2 := curve.ScalarMult(pub.X, pub.Y, k.Bytes())
		x1Buf := x1.Bytes()
		y1Buf := y1.Bytes()
		x2Buf := x2.Bytes()
		y2Buf := y2.Bytes()
		if n := len(x1Buf); n < 32 {
			x1Buf = append(zeroByteSlice()[:32-n], x1Buf...)
		}
		if n := len(y1Buf); n < 32 {
			y1Buf = append(zeroByteSlice()[:32-n], y1Buf...)
		}
		if n := len(x2Buf); n < 32 {
			x2Buf = append(zeroByteSlice()[:32-n], x2Buf...)
		}
		if n := len(y2Buf); n < 32 {
			y2Buf = append(zeroByteSlice()[:32-n], y2Buf...)
		}
		c = append(c, x1Buf...) // x分量
		c = append(c, y1Buf...) // y分量
		tm := []byte{}
		tm = append(tm, x2Buf...)
		tm = append(tm, data...)
		tm = append(tm, y2Buf...)
		h := sm3.Sm3Sum(tm)
		c = append(c, h...)
		ct, ok := kdf(x2Buf, y2Buf, length) // 密文
		if !ok {
			continue
		}
		c = append(c, ct...)
		for i := 0; i < length; i++ {
			c[96+i] ^= data[i]
		}
		return append([]byte{0x04}, c...), nil
	}
}

func Decrypt(priv *PrivateKey, data []byte) ([]byte, error) {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Decrypt 2' runing ")

	data = data[1:]
	length := len(data) - 96
	curve := priv.Curve
	x := new(big.Int).SetBytes(data[:32])
	y := new(big.Int).SetBytes(data[32:64])
	x2, y2 := curve.ScalarMult(x, y, priv.D.Bytes())
	x2Buf := x2.Bytes()
	y2Buf := y2.Bytes()
	if n := len(x2Buf); n < 32 {
		x2Buf = append(zeroByteSlice()[:32-n], x2Buf...)
	}
	if n := len(y2Buf); n < 32 {
		y2Buf = append(zeroByteSlice()[:32-n], y2Buf...)
	}
	c, ok := kdf(x2Buf, y2Buf, length)
	if !ok {
		return nil, errors.New("Decrypt: failed to decrypt")
	}
	for i := 0; i < length; i++ {
		c[i] ^= data[i+96]
	}
	tm := []byte{}
	tm = append(tm, x2Buf...)
	tm = append(tm, c...)
	tm = append(tm, y2Buf...)
	h := sm3.Sm3Sum(tm)
	if bytes.Compare(h, data[64:96]) != 0 {
		return c, errors.New("Decrypt: failed to decrypt")
	}
	return c, nil
}

type zr struct {
	io.Reader
}

func (z *zr) Read(dst []byte) (n int, err error) {
	for i := range dst {
		dst[i] = 0
	}
	return len(dst), nil
}

var zeroReader = &zr{}

func getLastBit(a *big.Int) uint {
	return a.Bit(0)
}

func Compress(a *PublicKey) []byte {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Compress 1' runing ")

	buf := []byte{}
	yp := getLastBit(a.Y)
	buf = append(buf, a.X.Bytes()...)
	if n := len(a.X.Bytes()); n < 32 {
		buf = append(zeroByteSlice()[:(32-n)], buf...)
	}
	buf = append([]byte{byte(yp)}, buf...)
	return buf
}

func Decompress(a []byte) *PublicKey {
	//fmt.Println("wcx Debug: [C:\\Go\\src\\gm-fabric-goclient\\vendor\\github.com\\hyperledger\\fabric-sdk-go\\internal\\github.com\\tjfoc\\gmsm\\sm2\\sm2.go] \n'Decompress 2' runing ")

	var aa, xx, xx3 sm2P256FieldElement

	P256Sm2()
	x := new(big.Int).SetBytes(a[1:])
	curve := sm2P256
	sm2P256FromBig(&xx, x)
	sm2P256Square(&xx3, &xx)       // x3 = x ^ 2
	sm2P256Mul(&xx3, &xx3, &xx)    // x3 = x ^ 2 * x
	sm2P256Mul(&aa, &curve.a, &xx) // a = a * x
	sm2P256Add(&xx3, &xx3, &aa)
	sm2P256Add(&xx3, &xx3, &curve.b)

	y2 := sm2P256ToBig(&xx3)
	y := new(big.Int).ModSqrt(y2, sm2P256.P)
	if getLastBit(y) != uint(a[0]) {
		y.Sub(sm2P256.P, y)
	}
	return &PublicKey{
		Curve: P256Sm2(),
		X:     x,
		Y:     y,
	}
}