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  #ifndef ANT_ENCRYPT_NEGOTIATION_SLAVE_H__
  #define ANT_ENCRYPT_NEGOTIATION_SLAVE_H__
  
  /**@file
   *
   * @defgroup ant_encrypt_negotiation_slave ANT encryption negotiation
   * @{
   * @ingroup  ant_sdk_utils
   *
   * @brief    Encryption negotiation for encrypted ANT slave channels.
   *
   * After pairing, the slave starts negotiating the encryption with the master. After
   * successful negotiation, the slave can decrypt messages from the master, and all
   * future messages are sent encrypted.
   *
   */
  
  #include <stdint.h>
  #include "ant_stack_handler_types.h"
  #include "ant_encrypt_config.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /** Encryption negotiation states for a slave channel. */
  typedef enum
  {
      ANT_ENC_CHANNEL_STAT_NOT_TRACKING,        ///< Not tracking the master.
      ANT_ENC_CHANNEL_STAT_TRACKING_ENCRYPTED,  ///< Tracking the master, but cannot decrypt messages.
      ANT_ENC_CHANNEL_STAT_NEGOTIATING,         ///< Encryption has been enabled and negotiation is in progress.
      ANT_ENC_CHANNEL_STAT_TRACKING_DECRYPTED,  ///< Tracking the master and can decrypt messages.
      ANT_ENC_CHANNEL_STAT_TRACKING_UNSUPPORTED ///< Tracking unsupported on this channel.
  } ant_encrypt_tracking_state_t;
  
  
  /**
   * @brief Function for setting the encryption negotiation state of a slave ANT channel.
   *
   * This function should be used by the @ref ant_encrypt_config module.
   *
   * @param[in] channel_number    ANT channel number.
   * @param[in] state             State to set.
   */
  void ant_channel_encryp_tracking_state_set(uint8_t                      channel_number,
                                             ant_encrypt_tracking_state_t state);
  
  /**
   * @brief Function for getting the encryption negotiation state of a slave ANT channel.
   *
   * @param[in] channel_number       ANT channel number.
   */
  ant_encrypt_tracking_state_t ant_channel_encryp_tracking_state_get(uint8_t channel_number);
  
  /**
   * @brief Function for initializing the module.
   *
   * This function initializes internal states of the module. It should
   * only be used by the @ref ant_encrypt_config module.
   *
   */
  void ant_channel_encryp_negotiation_slave_init(void);
  
  /**
   * @brief Function for setting the configuration for the slave channel.
   *
   * This function saves the channel's encryption configuration to a lookup table (LUT) for
   * future usage. The configuration can then be used to enable encryption.
   *
   * This function is intended to be used by the @ref ant_encrypt_config module.
   *
   * @param[in] channel_number   ANT channel number.
   * @param[in] p_crypto_config  Pointer to the encryption configuration.
   */
  void ant_slave_channel_encrypt_config(uint8_t                                      channel_number,
                                        ant_encrypt_channel_settings_t const * const p_crypto_config);
  
  
  /**
   * @brief Function for handling ANT encryption negotiation on slave nodes.
   *
   * This function should be used directly in the ANT event dispatching process. It
   * tries to enable slave channel encryption for all slave channels that are declared
   * as encrypted channels (if appropriate master channels are found).
   *
   * This function should be used by the @ref ant_encrypt_config module.
   *
   * @param[in] p_ant_evt  Pointer to the ANT stack event message structure.
   */
  void ant_slave_encrypt_negotiation(ant_evt_t * p_ant_evt);
  
  
  /**
   * @}
   */
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif // ANT_ENCRYPT_NEGOTIATION_SLAVE_H__
  