use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>

vendor/github.com/lucas-clemente/quic-go/internal/crypto/curve_25519.go

@@ -0,0 +1,41 @@
+package crypto
+
+import (
+	"crypto/rand"
+	"errors"
+
+	"golang.org/x/crypto/curve25519"
+)
+
+// KeyExchange manages the exchange of keys
+type curve25519KEX struct {
+	secret [32]byte
+	public [32]byte
+}
+
+var _ KeyExchange = &curve25519KEX{}
+
+// NewCurve25519KEX creates a new KeyExchange using Curve25519, see https://cr.yp.to/ecdh.html
+func NewCurve25519KEX() (KeyExchange, error) {
+	c := &curve25519KEX{}
+	if _, err := rand.Read(c.secret[:]); err != nil {
+		return nil, errors.New("Curve25519: could not create private key")
+	}
+	curve25519.ScalarBaseMult(&c.public, &c.secret)
+	return c, nil
+}
+
+func (c *curve25519KEX) PublicKey() []byte {
+	return c.public[:]
+}
+
+func (c *curve25519KEX) CalculateSharedKey(otherPublic []byte) ([]byte, error) {
+	if len(otherPublic) != 32 {
+		return nil, errors.New("Curve25519: expected public key of 32 byte")
+	}
+	var res [32]byte
+	var otherPublicArray [32]byte
+	copy(otherPublicArray[:], otherPublic)
+	curve25519.ScalarMult(&res, &c.secret, &otherPublicArray)
+	return res[:], nil
+}