init: v1.0.0

implicitcert/userkey.go

@@ -0,0 +1,86 @@
+package implicitcert
+
+import (
+	"fmt"
+	"io"
+	"math/big"
+
+	"xdx.jelly/xgcl/sm/sm2"
+	"xdx.jelly/xgcl/sm/sm3"
+)
+
+var (
+	ErrClientGenerateAgreementData = fmt.Errorf("client GenerateAgreementData error")
+	errZeroPrivateKey              = fmt.Errorf("private key got zero")
+)
+
+type UserKey struct {
+	d *sm2.PrivateKey // user's private key
+	// w sm2.PublicKey   // declare public key
+}
+
+func NewUserKey() *UserKey {
+	return &UserKey{}
+}
+
+// GeneratePartialKey generate UserKey.d and partial public key U.
+// Then user should send ID and U to kgc.
+// The Input r should be a random number Reader.
+// r could use grand.Reader, or a wrapper of random generator from hard ware.
+// If want pass in a b of []byte slice, use grand.NewReaderFromBytes(b) to turn b to a
+// Reader:
+// b := []byte{...}
+// pk,err := u.GeneratePartialKey(grand.NewReaderFromBytes(b))
+func (uk *UserKey) GeneratePartialKey(r io.Reader) (*sm2.PublicKey, error) {
+	rnd := make([]byte, sm2.ByteSize())
+	_, err := r.Read(rnd)
+	if err != nil {
+		return nil, err
+	}
+	uk.d, _ = sm2.GenPrivateKey(rnd)
+	u := sm2.GenPublicKey(uk.d)
+	return u, nil
+}
+
+// GeneratePrivateKey generate user's privatekey and the declare public key
+// t - KGC generated partial private key for user
+func (uk *UserKey) GeneratePrivateKey(kgcGeneratedUserPartialPrivateKey *sm2.PrivateKey) (userPrivateKey *sm2.PrivateKey, err error) {
+	d := new(big.Int)
+	d.Add(uk.d.D, kgcGeneratedUserPartialPrivateKey.D)
+	ret := d.Cmp(sm2.OrderN())
+	if ret == 0 {
+		return nil, errZeroPrivateKey
+	}
+	if ret > 0 {
+		d.Sub(d, sm2.OrderN())
+	}
+
+	return &sm2.PrivateKey{D: d}, nil
+
+}
+
+// VerifyUserKeyPair verify the private key and declare public key are correct
+func VerifyUserKeyPair(
+	id []byte,
+	userPrivateKey *sm2.PrivateKey,
+	userDeclarePublicKey *sm2.PublicKey,
+	kgcPublicKey *sm2.PublicKey) bool {
+
+	return sm2.VerifyKeyPair(userPrivateKey, RestoreUserPublicKey(id, userDeclarePublicKey, kgcPublicKey))
+}
+
+// RestoreUserPublicKey restore user's public key from id, kgc's public key and user's
+// declare public key
+func RestoreUserPublicKey(
+	id []byte,
+	userDeclarePublicKey *sm2.PublicKey,
+	kgcPublicKey *sm2.PublicKey) *sm2.PublicKey {
+
+	h := sm2.PreComputeWithIdAndPubkey(id, kgcPublicKey)
+	lambda := sm3.Sum(userDeclarePublicKey.Bytes(), h)
+
+	x1, y1 := sm2.Curve().ScalarMult(kgcPublicKey.X, kgcPublicKey.Y, lambda[:])
+	x1, y1 = sm2.Curve().Add(x1, y1, userDeclarePublicKey.X, userDeclarePublicKey.Y)
+
+	return &sm2.PublicKey{X: x1, Y: y1}
+}