add encryption (#1002)

* add encryption

* add doc

* add doc

* fix bug

fastdeploy/encryption/util/include/io_utils.h

@@ -0,0 +1,53 @@
+// Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+//
+// 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.
+#pragma once
+
+#include <iostream>
+#include <memory>
+#include <vector>
+#include <string>
+
+#ifndef PADDLE_MODEL_PROTECT_IO_UTILS_H
+#define PADDLE_MODEL_PROTECT_IO_UTILS_H
+namespace fastdeploy {
+namespace ioutil {
+
+int read_file(const char* file_path, unsigned char** dataptr, size_t* sizeptr);
+
+int read_with_pos_and_length(const char* file_path, unsigned char* dataptr,
+                             size_t pos, size_t length);
+
+int read_with_pos(const char* file_path, size_t pos, unsigned char** dataptr,
+                  size_t* sizeptr);
+
+int write_file(const char* file_path, const unsigned char* dataptr,
+               size_t sizeptr);
+
+int append_file(const char* file_path, const unsigned char* data, size_t len);
+
+size_t read_file_size(const char* file_path);
+
+int read_file_to_file(const char* src_path, const char* dst_path);
+
+int dir_exist_or_mkdir(const char* dir);
+
+/**
+ * @return files.size()
+ */
+int read_dir_files(const char* dir_path,
+                   std::vector<std::string>& files);  // NOLINT
+
+}  // namespace ioutil
+}  // namespace fastdeploy
+#endif  // PADDLE_MODEL_PROTECT_IO_UTILS_H