// Copyright 2021 Google LLC. All Rights Reserved. This file and proprietary
// source code may only be used and distributed under the Widevine License
// Agreement.
//
//  Reference implementation utilities of OEMCrypto APIs
//
#ifndef WVOEC_UTIL_KEY_DERIVER_H_
#define WVOEC_UTIL_KEY_DERIVER_H_

#include <inttypes.h>
#include <stddef.h>

#include <memory>
#include <vector>

#include "cmac.h"
#include "wv_class_utils.h"

namespace wvoec {
namespace util {
class KeyDeriver {
 public:
  ~KeyDeriver() = default;
  WVCDM_DISALLOW_COPY_AND_MOVE(KeyDeriver);

  // Create a new key deriver using either the session key or the device
  // key.
  // Returns an empty pointer if the key size is not valid.
  static std::unique_ptr<KeyDeriver> Create(const uint8_t* key,
                                            size_t key_size);
  static std::unique_ptr<KeyDeriver> Create(const std::vector<uint8_t>& key);

  // Derive the mac_key[server] from the provided |mac_key_context|.
  bool DeriveServerMacKey(const uint8_t* mac_key_context,
                          size_t mac_key_context_size,
                          std::vector<uint8_t>* mac_key_server);
  bool DeriveServerMacKey(const std::vector<uint8_t>& mac_key_context,
                          std::vector<uint8_t>* mac_key_server);

  // Derive the mac_key[client] from the provided |mac_key_context|.
  bool DeriveClientMacKey(const uint8_t* mac_key_context,
                          size_t mac_key_context_size,
                          std::vector<uint8_t>* mac_key_client);
  bool DeriveClientMacKey(const std::vector<uint8_t>& mac_key_context,
                          std::vector<uint8_t>* mac_key_client);

  // Derive the enc_key from the provided |enc_key_context|.
  bool DeriveEncryptionKey(const uint8_t* enc_key_context,
                           size_t enc_key_context_size,
                           std::vector<uint8_t>* enc_key);
  bool DeriveEncryptionKey(const std::vector<uint8_t>& enc_key_context,
                           std::vector<uint8_t>* enc_key);

  // Derive renewed device key. Use on KeyDeriver initialized with old device
  // key. |context| should be just the context field, eg A_priv+CA_token.
  bool DeriveRenewedDeviceKey(const std::vector<uint8_t>& context,
                              std::vector<uint8_t>* renewed_device_key);

 private:
  KeyDeriver() {}

  bool Init(const uint8_t* key, size_t key_size);

  std::unique_ptr<Cmac> cmac_;
};  // class KeyDeriver
}  // namespace util
}  // namespace wvoec
#endif  // WVOEC_UTIL_KEY_DERIVER_H_