add encryption (#1002)

* add encryption

* add doc

* add doc

* fix bug

fastdeploy/encryption/include/decrypt.h

@@ -0,0 +1,60 @@
+//   Copyright (c) 2022 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 <stdio.h>
+#include <string>
+
+#include "fastdeploy/utils/utils.h"
+
+#ifndef PADDLE_MODEL_PROTECT_API_PADDLE_MODEL_DECRYPT_H
+#define PADDLE_MODEL_PROTECT_API_PADDLE_MODEL_DECRYPT_H
+namespace fastdeploy {
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** \brief check stream is encrypted or not
+ *
+ * \param[in] cipher_stream The encrypted stream
+ * \return 0 if stream is encrypted.
+ */
+FASTDEPLOY_DECL int CheckStreamEncrypted(std::istream& cipher_stream);
+
+
+/** \brief decrypt an encrypted stream
+ *
+ * \param[in] cipher_stream The encrypted stream
+ * \param[in] plain_stream The decrypted stream
+ * \param[in] key_base64 The key for decryption
+ * \return 0 if decrypt success.
+ */
+FASTDEPLOY_DECL int DecryptStream(std::istream& cipher_stream,
+                                 std::ostream& plain_stream,
+                                 const std::string& key_base64);
+
+
+/** \brief decrypt an encrypted string
+ *
+ * \param[in] cipher The encrypted string
+ * \param[in] key The key for decryption
+ * \return The decrypted string
+ */
+FASTDEPLOY_DECL std::string Decrypt(const std::string& cipher,
+                  const std::string& key);
+#ifdef __cplusplus
+}
+#endif
+}  // namespace fastdeploy
+#endif  // PADDLE_MODEL_PROTECT_API_PADDLE_MODEL_DECRYPT_H