start refactoring

utils/crypto/encode.go

@@ -0,0 +1,93 @@
+// Copyright 2017 fatedier, fatedier@gmail.com
+//
+// 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 crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha1"
+	"io"
+
+	"golang.org/x/crypto/pbkdf2"
+)
+
+const (
+	salt = "frp"
+)
+
+// NewWriter returns a new Writer that encrypts bytes to w.
+func NewWriter(w io.Writer, key []byte) (*Writer, error) {
+	key = pbkdf2.Key(key, []byte(salt), 64, aes.BlockSize, sha1.New)
+
+	// random iv
+	iv := make([]byte, aes.BlockSize)
+	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+		return nil, err
+	}
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Writer{
+		w: w,
+		enc: &cipher.StreamWriter{
+			S: cipher.NewCFBEncrypter(block, iv),
+			W: w,
+		},
+		key: key,
+		iv:  iv,
+	}, nil
+}
+
+// Writer is an io.Writer that can write encrypted bytes.
+// Now it only support aes-128-cfb.
+type Writer struct {
+	w      io.Writer
+	enc    *cipher.StreamWriter
+	key    []byte
+	iv     []byte
+	ivSend bool
+	err    error
+}
+
+// Write satisfies the io.Writer interface.
+func (w *Writer) Write(p []byte) (nRet int, errRet error) {
+	return w.write(p)
+}
+
+func (w *Writer) write(p []byte) (nRet int, errRet error) {
+	if w.err != nil {
+		return 0, w.err
+	}
+
+	// When write is first called, iv will be written to w.w
+	if !w.ivSend {
+		w.ivSend = true
+		_, errRet = w.w.Write(w.iv)
+		if errRet != nil {
+			w.err = errRet
+			return
+		}
+	}
+
+	nRet, errRet = w.enc.Write(p)
+	if errRet != nil {
+		w.err = errRet
+	}
+	return
+}