+bool contrac_generate_tracing_key(Contrac * data);
+bool contrac_set_day_number(Contrac * data, uint32_t day_number);
+bool contrac_set_time_interval_number(Contrac * data, uint8_t time_interval_number);
+bool contrac_update_current_time(Contrac * data);
+bool contrac_get_initialised(Contrac const * data);
+uint32_t contrac_get_day_number(Contrac * data);
+uint8_t contrac_get_time_interval_number(Contrac * data);
+
+unsigned char const * contrac_get_tracing_key(Contrac const * data);
+void contrac_get_tracing_key_base64(Contrac const * data, char * base64);
+
+void contrac_set_tracing_key(Contrac * data, unsigned char const * tracing_key);
+bool contrac_set_tracing_key_base64(Contrac * data, char const * tracing_key);
+
+unsigned char const * contrac_get_daily_key(Contrac const * data);
+void contrac_get_daily_key_base64(Contrac const * data, char * base64);
+
+unsigned char const * contrac_get_proximity_id(Contrac const * data);
+void contrac_get_proximity_id_base64(Contrac const * data, char * base64);
+
+// Function definitions
+