Minor changes

README.md

@@ -1,5 +1,5 @@
 # fake115uploader
-模拟115网盘客户端的上传功能，部分实现参考 [Fake115Upload](https://github.com/T3rry7f/Fake115Upload)
+模拟115网盘客户端的上传功能，部分实现参考 [Fake115Upload](https://github.com/T3rry7f/Fake115Upload)，仅用于研究目的
 
 ### 特点
 * 支持秒传模式，需要已经有人上传过指定文件到115

cipher/cipher.go

@@ -45,6 +45,7 @@ type Cipher struct {
 	publicKey  *rsa.PublicKey
 	privateKey *rsa.PrivateKey
 	randKey    []byte
+	keyS       []byte
 }
 
 // NewCipher 新建Cipher
@@ -68,60 +69,28 @@ func NewCipher() (*Cipher, error) {
 	}
 	c.privateKey = privateKey
 
-	randKey := make([]byte, keySize)
-	_, err = rand.Read(randKey)
-	if err != nil {
-		return nil, err
-	}
-	c.randKey = randKey
-
 	return c, nil
 }
 
 // 生成key
-func genKey(randKey []byte, keyLen int) []byte {
-	xorKey := make([]byte, 0, keyLen)
-	length := keyLen * (keyLen - 1)
-	index := 0
-	if len(randKey) != 0 {
-		for i := 0; i < keyLen; i++ {
-			x := byte(uint8(randKey[i]) + uint8(gKts[index]))
-			xorKey = append(xorKey, gKts[length]^x)
-			length -= keyLen
-			index += keyLen
-		}
-	}
-
-	return xorKey
-}
-
-// 利用key进行异或操作
-func xor(src, key []byte) []byte {
-	secret := make([]byte, 0, len(src))
-	pad := len(src) % 4
-	if pad > 0 {
-		for i := 0; i < pad; i++ {
-			secret = append(secret, src[i]^key[i])
-		}
-		src = src[pad:]
-	}
-	keyLen := len(key)
-	num := 0
-	for _, s := range src {
-		if num >= keyLen {
-			num = num % keyLen
-		}
-		secret = append(secret, s^key[num])
-		num++
+func (c *Cipher) genKey() error {
+	c.randKey = make([]byte, keySize)
+	_, err := rand.Read(c.randKey)
+	if err != nil {
+		return err
 	}
+	c.keyS = genKey(c.randKey, 4)
 
-	return secret
+	return nil
 }
 
-// Encrypt 加密
+// Encrypt 加密，一次加密对应一次解密
 func (c *Cipher) Encrypt(plainText []byte) ([]byte, error) {
-	keyS := genKey(c.randKey, 4)
-	tmp := xor(plainText, keyS)
+	err := c.genKey()
+	if err != nil {
+		return nil, err
+	}
+	tmp := xor(plainText, c.keyS)
 	for i, j := 0, len(tmp)-1; i < j; i, j = i+1, j-1 {
 		tmp[i], tmp[j] = tmp[j], tmp[i]
 	}
@@ -138,7 +107,7 @@ func (c *Cipher) Encrypt(plainText []byte) ([]byte, error) {
 	return text, nil
 }
 
-// Decrypt 解密
+// Decrypt 解密，一次加密对应一次解密
 func (c *Cipher) Decrypt(cipherText []byte) ([]byte, error) {
 	text := make([]byte, base64.StdEncoding.DecodedLen(len(cipherText)))
 	n, err := base64.StdEncoding.Decode(text, cipherText)
@@ -157,13 +126,52 @@ func (c *Cipher) Decrypt(cipherText []byte) ([]byte, error) {
 	}
 	randKey := plainText[:keySize]
 	plainText = plainText[keySize:]
-	keyS := genKey(c.randKey, 4)
 	keyL := genKey(randKey, 12)
 	tmp := xor(plainText, keyL)
 	for i, j := 0, len(tmp)-1; i < j; i, j = i+1, j-1 {
 		tmp[i], tmp[j] = tmp[j], tmp[i]
 	}
-	plainText = xor(tmp, keyS)
+	plainText = xor(tmp, c.keyS)
 
 	return plainText, nil
 }
+
+// 生成key
+func genKey(randKey []byte, keyLen int) []byte {
+	xorKey := make([]byte, 0, keyLen)
+	length := keyLen * (keyLen - 1)
+	index := 0
+	if len(randKey) != 0 {
+		for i := 0; i < keyLen; i++ {
+			x := byte(uint8(randKey[i]) + uint8(gKts[index]))
+			xorKey = append(xorKey, gKts[length]^x)
+			length -= keyLen
+			index += keyLen
+		}
+	}
+
+	return xorKey
+}
+
+// 利用key进行异或操作
+func xor(src, key []byte) []byte {
+	secret := make([]byte, 0, len(src))
+	pad := len(src) % 4
+	if pad > 0 {
+		for i := 0; i < pad; i++ {
+			secret = append(secret, src[i]^key[i])
+		}
+		src = src[pad:]
+	}
+	keyLen := len(key)
+	num := 0
+	for _, s := range src {
+		if num >= keyLen {
+			num = num % keyLen
+		}
+		secret = append(secret, s^key[num])
+		num++
+	}
+
+	return secret
+}