API encryption (#2254)

esphome/components/api/api_noise_context.h

@@ -0,0 +1,23 @@
+#pragma once
+#include <cstdint>
+#include <array>
+#include "esphome/core/defines.h"
+
+namespace esphome {
+namespace api {
+
+#ifdef USE_API_NOISE
+using psk_t = std::array<uint8_t, 32>;
+
+class APINoiseContext {
+ public:
+  void set_psk(psk_t psk) { psk_ = std::move(psk); }
+  const psk_t &get_psk() const { return psk_; }
+
+ protected:
+  psk_t psk_;
+};
+#endif  // USE_API_NOISE
+
+}  // namespace api
+}  // namespace esphome