init: 1.0.0

pkg/tool/curve25519.go

@@ -0,0 +1,51 @@
+package tool
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+
+	"github.com/pkg/errors"
+
+	"golang.org/x/crypto/curve25519"
+)
+
+func Curve25519Genkey(StdEncoding bool, inputBase64 string) (public, private string, err error) {
+	var privateKey, publicKey []byte
+	var encoding *base64.Encoding
+	if StdEncoding {
+		encoding = base64.StdEncoding
+	} else {
+		encoding = base64.RawURLEncoding
+	}
+
+	if len(inputBase64) > 0 {
+		privateKey, err = encoding.DecodeString(inputBase64)
+		if err != nil {
+			goto out
+		}
+		if len(privateKey) != curve25519.ScalarSize {
+			err = errors.New("Invalid length of private key.")
+			goto out
+		}
+	}
+
+	if privateKey == nil {
+		privateKey = make([]byte, curve25519.ScalarSize)
+		if _, err = rand.Read(privateKey); err != nil {
+			goto out
+		}
+	}
+
+	// Modify random bytes using algorithm described at:
+	// https://cr.yp.to/ecdh.html.
+	privateKey[0] &= 248
+	privateKey[31] &= 127 | 64
+
+	if publicKey, err = curve25519.X25519(privateKey, curve25519.Basepoint); err != nil {
+		goto out
+	}
+	public = encoding.EncodeToString(publicKey)
+	private = encoding.EncodeToString(privateKey)
+out:
+	return public, private, err
+}