diff --git a/sm2/sm2_keyexchange.go b/sm2/sm2_keyexchange.go index c980349..7c6fe49 100644 --- a/sm2/sm2_keyexchange.go +++ b/sm2/sm2_keyexchange.go @@ -35,10 +35,14 @@ func (ke *KeyExchange) GetSharedKey() []byte { } // NewKeyExchange create one new KeyExchange object +// +// 在部分场景中，在初始 KeyExchange 时暂时没有对端的公开信息（如公钥、UID），这些信息可能需要在后续的交换中得到。 +// 这种情况下，可设置 peerPub、peerUID 参数为 nil，并在合适的时候通过 KeyExchange.SetPeerParameters 方法配置相关参数。 +// 注意 KeyExchange.SetPeerParameters 方法必须要在 KeyExchange.RepondKeyExchange 或 KeyExchange.RepondKeyExchange 方法之前调用。 func NewKeyExchange(priv *PrivateKey, peerPub *ecdsa.PublicKey, uid, peerUID []byte, keyLen int, genSignature bool) (ke *KeyExchange, err error) { ke = &KeyExchange{} ke.genSignature = genSignature - ke.peerPub = peerPub + ke.keyLength = keyLen ke.privateKey = priv w := (priv.Params().N.BitLen()+1)/2 - 1 @@ -48,24 +52,55 @@ func NewKeyExchange(priv *PrivateKey, peerPub *ecdsa.PublicKey, uid, peerUID []b x2minus1 := (&big.Int{}).Sub(x2, big.NewInt(1)) ke.w2Minus1 = x2minus1 + if len(uid) == 0 { + uid = defaultUID + } ke.z, err = calculateZA(&ke.privateKey.PublicKey, uid) if err != nil { return nil, err } - ke.peerZ, err = calculateZA(ke.peerPub, peerUID) + + err = ke.SetPeerParameters(peerPub, peerUID) if err != nil { return nil, err } + ke.secret = &ecdsa.PublicKey{} ke.secret.Curve = priv.PublicKey.Curve - ke.peerSecret = &ecdsa.PublicKey{} - ke.peerSecret.Curve = peerPub.Curve + ke.v = &ecdsa.PublicKey{} ke.v.Curve = priv.PublicKey.Curve return } +// SetPeerParameters 设置对端公开信息，该方法用于某些初期状态无法取得对端公开参数的场景。 +// 例如：在TLCP协议中，基于SM2算法ECDHE过程。 +// +// 注意该方法仅在 NewKeyExchange 没有提供 peerPub、peerUID参数时允许被调用， +// 且该方法只能调用一次不可重复调用，若多次调用或peerPub、peerUID已经存在则会发生错误。 +func (ke *KeyExchange) SetPeerParameters(peerPub *ecdsa.PublicKey, peerUID []byte) error { + if peerPub == nil { + return nil + } + if len(peerUID) == 0 { + peerUID = defaultUID + } + if ke.peerPub != nil { + return errors.New("sm2: 'peerPub' already exists, please do not set it") + } + + var err error + ke.peerPub = peerPub + ke.peerZ, err = calculateZA(ke.peerPub, peerUID) + if err != nil { + return err + } + ke.peerSecret = &ecdsa.PublicKey{} + ke.peerSecret.Curve = peerPub.Curve + return nil +} + func initKeyExchange(ke *KeyExchange, r *big.Int) { ke.secret.X, ke.secret.Y = ke.privateKey.ScalarBaseMult(r.Bytes()) ke.r = r @@ -154,6 +189,9 @@ func respondKeyExchange(ke *KeyExchange, r *big.Int, rA *ecdsa.PublicKey) (*ecds // RepondKeyExchange when responder receive rA, for responder's step B1-B8 func (ke *KeyExchange) RepondKeyExchange(rand io.Reader, rA *ecdsa.PublicKey) (*ecdsa.PublicKey, []byte, error) { + if ke.peerPub == nil { + return nil, nil, errors.New("sm2: peer public not set, you probable need call KeyExchange.SetPeerParameters") + } if !ke.privateKey.IsOnCurve(rA.X, rA.Y) { return nil, nil, errors.New("sm2: received invalid random from initiator") } @@ -167,6 +205,9 @@ func (ke *KeyExchange) RepondKeyExchange(rand io.Reader, rA *ecdsa.PublicKey) (* // ConfirmResponder for initiator's step A4-A10 func (ke *KeyExchange) ConfirmResponder(rB *ecdsa.PublicKey, sB []byte) ([]byte, error) { + if ke.peerPub == nil { + return nil, errors.New("sm2: peer public not set, you probable need call KeyExchange.SetPeerParameters") + } if !ke.privateKey.IsOnCurve(rB.X, rB.Y) { return nil, errors.New("sm2: received invalid random from responder") } diff --git a/sm2/sm2_keyexchange_test.go b/sm2/sm2_keyexchange_test.go index bf14989..99e232d 100644 --- a/sm2/sm2_keyexchange_test.go +++ b/sm2/sm2_keyexchange_test.go @@ -3,6 +3,7 @@ package sm2 import ( "crypto/rand" "encoding/hex" + "errors" "testing" ) @@ -41,3 +42,148 @@ func TestKeyExchangeSample(t *testing.T) { t.Errorf("got different key") } } + +func TestSetPeerParameters(t *testing.T) { + priv1, _ := GenerateKey(rand.Reader) + priv2, _ := GenerateKey(rand.Reader) + uidA := []byte("Alice") + uidB := []byte("Bob") + + initiator, err := NewKeyExchange(priv1, nil, uidA, uidB, 32, true) + if err != nil { + t.Fatal(err) + } + responder, err := NewKeyExchange(priv2, nil, uidB, uidA, 32, true) + if err != nil { + t.Fatal(err) + } + + rA, err := initiator.InitKeyExchange(rand.Reader) + if err != nil { + t.Fatal(err) + } + + // 设置对端参数 + err = initiator.SetPeerParameters(&priv2.PublicKey, uidB) + if err != nil { + t.Fatal(err) + } + err = responder.SetPeerParameters(&priv1.PublicKey, uidA) + if err != nil { + t.Fatal(err) + } + + rB, s2, err := responder.RepondKeyExchange(rand.Reader, rA) + if err != nil { + t.Fatal(err) + } + + s1, err := initiator.ConfirmResponder(rB, s2) + if err != nil { + t.Fatal(err) + } + + err = responder.ConfirmInitiator(s1) + if err != nil { + t.Fatal(err) + } + + if hex.EncodeToString(initiator.key) != hex.EncodeToString(responder.key) { + t.Errorf("got different key") + } +} + +func TestKeyExchange_SetPeerParameters(t *testing.T) { + priv1, _ := GenerateKey(rand.Reader) + priv2, _ := GenerateKey(rand.Reader) + uidA := []byte("Alice") + uidB := []byte("Bob") + + initiator, err := NewKeyExchange(priv1, nil, uidA, nil, 32, true) + if err != nil { + t.Fatal(err) + } + responder, err := NewKeyExchange(priv2, nil, uidB, nil, 32, true) + if err != nil { + t.Fatal(err) + } + + rA, err := initiator.InitKeyExchange(rand.Reader) + if err != nil { + t.Fatal(err) + } + + // 设置对端参数 + err = initiator.SetPeerParameters(&priv2.PublicKey, uidB) + if err != nil { + t.Fatal(err) + } + err = responder.SetPeerParameters(&priv1.PublicKey, uidA) + if err != nil { + t.Fatal(err) + } + + rB, s2, err := responder.RepondKeyExchange(rand.Reader, rA) + if err != nil { + t.Fatal(err) + } + + s1, err := initiator.ConfirmResponder(rB, s2) + if err != nil { + t.Fatal(err) + } + + err = responder.ConfirmInitiator(s1) + if err != nil { + t.Fatal(err) + } + + if hex.EncodeToString(initiator.key) != hex.EncodeToString(responder.key) { + t.Errorf("got different key") + } +} + +func TestKeyExchange_SetPeerParameters_ErrCase(t *testing.T) { + priv1, _ := GenerateKey(rand.Reader) + priv2, _ := GenerateKey(rand.Reader) + uidA := []byte("Alice") + uidB := []byte("Bob") + + initiator, err := NewKeyExchange(priv1, nil, uidA, nil, 32, true) + if err != nil { + t.Fatal(err) + } + responder, err := NewKeyExchange(priv2, &priv1.PublicKey, uidB, uidA, 32, true) + if err != nil { + t.Fatal(err) + } + + rA, err := initiator.InitKeyExchange(rand.Reader) + if err != nil { + t.Fatal(err) + } + rB, s2, err := responder.RepondKeyExchange(rand.Reader, rA) + if err != nil { + t.Fatal(err) + } + + _, err = initiator.ConfirmResponder(rB, s2) + if err == nil { + t.Fatal(errors.New("expect call ConfirmResponder got a error, but not")) + } + + err = initiator.SetPeerParameters(&priv2.PublicKey, uidB) + if err != nil { + t.Fatal(err) + } + + err = initiator.SetPeerParameters(&priv2.PublicKey, uidB) + if err == nil { + t.Fatal(errors.New("expect call SetPeerParameters repeat got a error, but not")) + } + + err = responder.SetPeerParameters(&priv1.PublicKey, uidA) + if err == nil { + t.Fatal(errors.New("expect responder call SetPeerParameters got a error, but not")) + } +}