API encryption (#2254)

esphome/components/api/__init__.py

@@ -1,3 +1,5 @@
+import base64
+
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome import automation
@@ -6,6 +8,7 @@ from esphome.const import (
     CONF_DATA,
     CONF_DATA_TEMPLATE,
     CONF_ID,
+    CONF_KEY,
     CONF_PASSWORD,
     CONF_PORT,
     CONF_REBOOT_TIMEOUT,
@@ -41,6 +44,22 @@ SERVICE_ARG_NATIVE_TYPES = {
     "float[]": cg.std_vector.template(float),
     "string[]": cg.std_vector.template(cg.std_string),
 }
+CONF_ENCRYPTION = "encryption"
+
+
+def validate_encryption_key(value):
+    value = cv.string_strict(value)
+    try:
+        decoded = base64.b64decode(value, validate=True)
+    except ValueError as err:
+        raise cv.Invalid("Invalid key format, please check it's using base64") from err
+
+    if len(decoded) != 32:
+        raise cv.Invalid("Encryption key must be base64 and 32 bytes long")
+
+    # Return original data for roundtrip conversion
+    return value
+
 
 CONFIG_SCHEMA = cv.Schema(
     {
@@ -63,6 +82,11 @@ CONFIG_SCHEMA = cv.Schema(
                 ),
             }
         ),
+        cv.Optional(CONF_ENCRYPTION): cv.Schema(
+            {
+                cv.Required(CONF_KEY): validate_encryption_key,
+            }
+        ),
     }
 ).extend(cv.COMPONENT_SCHEMA)
 
@@ -92,6 +116,15 @@ async def to_code(config):
         cg.add(var.register_user_service(trigger))
         await automation.build_automation(trigger, func_args, conf)
 
+    if CONF_ENCRYPTION in config:
+        conf = config[CONF_ENCRYPTION]
+        decoded = base64.b64decode(conf[CONF_KEY])
+        cg.add(var.set_noise_psk(list(decoded)))
+        cg.add_define("USE_API_NOISE")
+        cg.add_library("esphome/noise-c", "0.1.1")
+    else:
+        cg.add_define("USE_API_PLAINTEXT")
+
     cg.add_define("USE_API")
     cg.add_global(api_ns.using)
 

esphome/components/api/api_connection.cpp

@@ -23,7 +23,13 @@ APIConnection::APIConnection(std::unique_ptr<socket::Socket> sock, APIServer *pa
     : parent_(parent), initial_state_iterator_(parent, this), list_entities_iterator_(parent, this) {
   this->proto_write_buffer_.reserve(64);
 
+#if defined(USE_API_PLAINTEXT)
   helper_ = std::unique_ptr<APIFrameHelper>{new APIPlaintextFrameHelper(std::move(sock))};
+#elif defined(USE_API_NOISE)
+  helper_ = std::unique_ptr<APIFrameHelper>{new APINoiseFrameHelper(std::move(sock), parent->get_noise_ctx())};
+#else
+#error "No frame helper defined"
+#endif
 }
 void APIConnection::start() {
   this->last_traffic_ = millis();

esphome/components/api/api_frame_helper.cpp

@@ -19,6 +19,617 @@ bool is_would_block(ssize_t ret) {
 
 #define HELPER_LOG(msg, ...) ESP_LOGVV(TAG, "%s: " msg, info_.c_str(), ##__VA_ARGS__)
 
+#ifdef USE_API_NOISE
+static const char *const PROLOGUE_INIT = "NoiseAPIInit";
+
+/// Convert a noise error code to a readable error
+std::string noise_err_to_str(int err) {
+  if (err == NOISE_ERROR_NO_MEMORY)
+    return "NO_MEMORY";
+  if (err == NOISE_ERROR_UNKNOWN_ID)
+    return "UNKNOWN_ID";
+  if (err == NOISE_ERROR_UNKNOWN_NAME)
+    return "UNKNOWN_NAME";
+  if (err == NOISE_ERROR_MAC_FAILURE)
+    return "MAC_FAILURE";
+  if (err == NOISE_ERROR_NOT_APPLICABLE)
+    return "NOT_APPLICABLE";
+  if (err == NOISE_ERROR_SYSTEM)
+    return "SYSTEM";
+  if (err == NOISE_ERROR_REMOTE_KEY_REQUIRED)
+    return "REMOTE_KEY_REQUIRED";
+  if (err == NOISE_ERROR_LOCAL_KEY_REQUIRED)
+    return "LOCAL_KEY_REQUIRED";
+  if (err == NOISE_ERROR_PSK_REQUIRED)
+    return "PSK_REQUIRED";
+  if (err == NOISE_ERROR_INVALID_LENGTH)
+    return "INVALID_LENGTH";
+  if (err == NOISE_ERROR_INVALID_PARAM)
+    return "INVALID_PARAM";
+  if (err == NOISE_ERROR_INVALID_STATE)
+    return "INVALID_STATE";
+  if (err == NOISE_ERROR_INVALID_NONCE)
+    return "INVALID_NONCE";
+  if (err == NOISE_ERROR_INVALID_PRIVATE_KEY)
+    return "INVALID_PRIVATE_KEY";
+  if (err == NOISE_ERROR_INVALID_PUBLIC_KEY)
+    return "INVALID_PUBLIC_KEY";
+  if (err == NOISE_ERROR_INVALID_FORMAT)
+    return "INVALID_FORMAT";
+  if (err == NOISE_ERROR_INVALID_SIGNATURE)
+    return "INVALID_SIGNATURE";
+  return to_string(err);
+}
+
+/// Initialize the frame helper, returns OK if successful.
+APIError APINoiseFrameHelper::init() {
+  if (state_ != State::INITIALIZE || socket_ == nullptr) {
+    HELPER_LOG("Bad state for init %d", (int) state_);
+    return APIError::BAD_STATE;
+  }
+  int err = socket_->setblocking(false);
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("Setting nonblocking failed with errno %d", errno);
+    return APIError::TCP_NONBLOCKING_FAILED;
+  }
+  int enable = 1;
+  err = socket_->setsockopt(IPPROTO_TCP, TCP_NODELAY, &enable, sizeof(int));
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("Setting nodelay failed with errno %d", errno);
+    return APIError::TCP_NODELAY_FAILED;
+  }
+
+  // init prologue
+  prologue_.insert(prologue_.end(), PROLOGUE_INIT, PROLOGUE_INIT + strlen(PROLOGUE_INIT));
+
+  state_ = State::CLIENT_HELLO;
+  return APIError::OK;
+}
+/// Run through handshake messages (if in that phase)
+APIError APINoiseFrameHelper::loop() {
+  APIError err = state_action_();
+  if (err == APIError::WOULD_BLOCK)
+    return APIError::OK;
+  if (err != APIError::OK)
+    return err;
+  if (!tx_buf_.empty()) {
+    err = try_send_tx_buf_();
+    if (err != APIError::OK) {
+      return err;
+    }
+  }
+  return APIError::OK;
+}
+
+/** Read a packet into the rx_buf_. If successful, stores frame data in the frame parameter
+ *
+ * @param frame: The struct to hold the frame information in.
+ *   msg_start: points to the start of the payload - this pointer is only valid until the next
+ *     try_receive_raw_ call
+ *
+ * @return 0 if a full packet is in rx_buf_
+ * @return -1 if error, check errno.
+ *
+ * errno EWOULDBLOCK: Packet could not be read without blocking. Try again later.
+ * errno ENOMEM: Not enough memory for reading packet.
+ * errno API_ERROR_BAD_INDICATOR: Bad indicator byte at start of frame.
+ * errno API_ERROR_HANDSHAKE_PACKET_LEN: Packet too big for this phase.
+ */
+APIError APINoiseFrameHelper::try_read_frame_(ParsedFrame *frame) {
+  int err;
+  APIError aerr;
+
+  if (frame == nullptr) {
+    HELPER_LOG("Bad argument for try_read_frame_");
+    return APIError::BAD_ARG;
+  }
+
+  // read header
+  if (rx_header_buf_len_ < 3) {
+    // no header information yet
+    size_t to_read = 3 - rx_header_buf_len_;
+    ssize_t received = socket_->read(&rx_header_buf_[rx_header_buf_len_], to_read);
+    if (is_would_block(received)) {
+      return APIError::WOULD_BLOCK;
+    } else if (received == -1) {
+      state_ = State::FAILED;
+      HELPER_LOG("Socket read failed with errno %d", errno);
+      return APIError::SOCKET_READ_FAILED;
+    }
+    rx_header_buf_len_ += received;
+    if (received != to_read) {
+      // not a full read
+      return APIError::WOULD_BLOCK;
+    }
+
+    // header reading done
+  }
+
+  // read body
+  uint8_t indicator = rx_header_buf_[0];
+  if (indicator != 0x01) {
+    state_ = State::FAILED;
+    HELPER_LOG("Bad indicator byte %u", indicator);
+    return APIError::BAD_INDICATOR;
+  }
+
+  uint16_t msg_size = (((uint16_t) rx_header_buf_[1]) << 8) | rx_header_buf_[2];
+
+  if (state_ != State::DATA && msg_size > 128) {
+    // for handshake message only permit up to 128 bytes
+    state_ = State::FAILED;
+    HELPER_LOG("Bad packet len for handshake: %d", msg_size);
+    return APIError::BAD_HANDSHAKE_PACKET_LEN;
+  }
+
+  // reserve space for body
+  if (rx_buf_.size() != msg_size) {
+    rx_buf_.resize(msg_size);
+  }
+
+  if (rx_buf_len_ < msg_size) {
+    // more data to read
+    size_t to_read = msg_size - rx_buf_len_;
+    ssize_t received = socket_->read(&rx_buf_[rx_buf_len_], to_read);
+    if (is_would_block(received)) {
+      return APIError::WOULD_BLOCK;
+    } else if (received == -1) {
+      state_ = State::FAILED;
+      HELPER_LOG("Socket read failed with errno %d", errno);
+      return APIError::SOCKET_READ_FAILED;
+    }
+    rx_buf_len_ += received;
+    if (received != to_read) {
+      // not all read
+      return APIError::WOULD_BLOCK;
+    }
+  }
+
+  // uncomment for even more debugging
+  // ESP_LOGVV(TAG, "Received frame: %s", hexencode(rx_buf_).c_str());
+  frame->msg = std::move(rx_buf_);
+  // consume msg
+  rx_buf_ = {};
+  rx_buf_len_ = 0;
+  rx_header_buf_len_ = 0;
+  return APIError::OK;
+}
+
+/** To be called from read/write methods.
+ *
+ * This method runs through the internal handshake methods, if in that state.
+ *
+ * If the handshake is still active when this method returns and a read/write can't take place at
+ * the moment, returns WOULD_BLOCK.
+ * If an error occured, returns that error. Only returns OK if the transport is ready for data
+ * traffic.
+ */
+APIError APINoiseFrameHelper::state_action_() {
+  int err;
+  APIError aerr;
+  if (state_ == State::INITIALIZE) {
+    HELPER_LOG("Bad state for method: %d", (int) state_);
+    return APIError::BAD_STATE;
+  }
+  if (state_ == State::CLIENT_HELLO) {
+    // waiting for client hello
+    ParsedFrame frame;
+    aerr = try_read_frame_(&frame);
+    if (aerr != APIError::OK)
+      return aerr;
+    // ignore contents, may be used in future for flags
+    prologue_.push_back((uint8_t)(frame.msg.size() >> 8));
+    prologue_.push_back((uint8_t) frame.msg.size());
+    prologue_.insert(prologue_.end(), frame.msg.begin(), frame.msg.end());
+
+    state_ = State::SERVER_HELLO;
+  }
+  if (state_ == State::SERVER_HELLO) {
+    // send server hello
+    uint8_t msg[1];
+    msg[0] = 0x01;  // chosen proto
+    aerr = write_frame_(msg, 1);
+    if (aerr != APIError::OK)
+      return aerr;
+
+    // start handshake
+    aerr = init_handshake_();
+    if (aerr != APIError::OK)
+      return aerr;
+
+    state_ = State::HANDSHAKE;
+  }
+  if (state_ == State::HANDSHAKE) {
+    int action = noise_handshakestate_get_action(handshake_);
+    if (action == NOISE_ACTION_READ_MESSAGE) {
+      // waiting for handshake msg
+      ParsedFrame frame;
+      aerr = try_read_frame_(&frame);
+      if (aerr == APIError::BAD_INDICATOR) {
+        send_explicit_handshake_reject_("Bad indicator byte");
+        return aerr;
+      }
+      if (aerr == APIError::BAD_HANDSHAKE_PACKET_LEN) {
+        send_explicit_handshake_reject_("Bad handshake packet len");
+        return aerr;
+      }
+      if (aerr != APIError::OK)
+        return aerr;
+
+      if (frame.msg.empty()) {
+        send_explicit_handshake_reject_("Empty handshake message");
+        return APIError::BAD_HANDSHAKE_PACKET_LEN;
+      } else if (frame.msg[0] != 0x00) {
+        HELPER_LOG("Bad handshake error byte: %u", frame.msg[0]);
+        send_explicit_handshake_reject_("Bad handshake error byte");
+        return APIError::BAD_HANDSHAKE_PACKET_LEN;
+      }
+
+      NoiseBuffer mbuf;
+      noise_buffer_init(mbuf);
+      noise_buffer_set_input(mbuf, frame.msg.data() + 1, frame.msg.size() - 1);
+      err = noise_handshakestate_read_message(handshake_, &mbuf, nullptr);
+      if (err != 0) {
+        // TODO: explicit rejection
+        state_ = State::FAILED;
+        HELPER_LOG("noise_handshakestate_read_message failed: %s", noise_err_to_str(err).c_str());
+        if (err == NOISE_ERROR_MAC_FAILURE) {
+          send_explicit_handshake_reject_("Handshake MAC failure");
+        } else {
+          send_explicit_handshake_reject_("Handshake error");
+        }
+        return APIError::HANDSHAKESTATE_READ_FAILED;
+      }
+
+      aerr = check_handshake_finished_();
+      if (aerr != APIError::OK)
+        return aerr;
+    } else if (action == NOISE_ACTION_WRITE_MESSAGE) {
+      uint8_t buffer[65];
+      NoiseBuffer mbuf;
+      noise_buffer_init(mbuf);
+      noise_buffer_set_output(mbuf, buffer + 1, sizeof(buffer) - 1);
+
+      err = noise_handshakestate_write_message(handshake_, &mbuf, nullptr);
+      if (err != 0) {
+        state_ = State::FAILED;
+        HELPER_LOG("noise_handshakestate_write_message failed: %s", noise_err_to_str(err).c_str());
+        return APIError::HANDSHAKESTATE_WRITE_FAILED;
+      }
+      buffer[0] = 0x00;  // success
+
+      aerr = write_frame_(buffer, mbuf.size + 1);
+      if (aerr != APIError::OK)
+        return aerr;
+      aerr = check_handshake_finished_();
+      if (aerr != APIError::OK)
+        return aerr;
+    } else {
+      // bad state for action
+      state_ = State::FAILED;
+      HELPER_LOG("Bad action for handshake: %d", action);
+      return APIError::HANDSHAKESTATE_BAD_STATE;
+    }
+  }
+  if (state_ == State::CLOSED || state_ == State::FAILED) {
+    return APIError::BAD_STATE;
+  }
+  return APIError::OK;
+}
+void APINoiseFrameHelper::send_explicit_handshake_reject_(const std::string &reason) {
+  std::vector<uint8_t> data;
+  data.reserve(reason.size() + 1);
+  data[0] = 0x01;  // failure
+  for (size_t i = 0; i < reason.size(); i++) {
+    data[i + 1] = (uint8_t) reason[i];
+  }
+  write_frame_(data.data(), data.size());
+}
+
+APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
+  int err;
+  APIError aerr;
+  aerr = state_action_();
+  if (aerr != APIError::OK) {
+    return aerr;
+  }
+
+  if (state_ != State::DATA) {
+    return APIError::WOULD_BLOCK;
+  }
+
+  ParsedFrame frame;
+  aerr = try_read_frame_(&frame);
+  if (aerr != APIError::OK)
+    return aerr;
+
+  NoiseBuffer mbuf;
+  noise_buffer_init(mbuf);
+  noise_buffer_set_inout(mbuf, frame.msg.data(), frame.msg.size(), frame.msg.size());
+  err = noise_cipherstate_decrypt(recv_cipher_, &mbuf);
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_cipherstate_decrypt failed: %s", noise_err_to_str(err).c_str());
+    return APIError::CIPHERSTATE_DECRYPT_FAILED;
+  }
+
+  size_t msg_size = mbuf.size;
+  uint8_t *msg_data = frame.msg.data();
+  if (msg_size < 4) {
+    state_ = State::FAILED;
+    HELPER_LOG("Bad data packet: size %d too short", msg_size);
+    return APIError::BAD_DATA_PACKET;
+  }
+
+  // uint16_t type;
+  // uint16_t data_len;
+  // uint8_t *data;
+  // uint8_t *padding;  zero or more bytes to fill up the rest of the packet
+  uint16_t type = (((uint16_t) msg_data[0]) << 8) | msg_data[1];
+  uint16_t data_len = (((uint16_t) msg_data[2]) << 8) | msg_data[3];
+  if (data_len > msg_size - 4) {
+    state_ = State::FAILED;
+    HELPER_LOG("Bad data packet: data_len %u greater than msg_size %u", data_len, msg_size);
+    return APIError::BAD_DATA_PACKET;
+  }
+
+  buffer->container = std::move(frame.msg);
+  buffer->data_offset = 4;
+  buffer->data_len = data_len;
+  buffer->type = type;
+  return APIError::OK;
+}
+bool APINoiseFrameHelper::can_write_without_blocking() { return state_ == State::DATA && tx_buf_.empty(); }
+APIError APINoiseFrameHelper::write_packet(uint16_t type, const uint8_t *payload, size_t payload_len) {
+  int err;
+  APIError aerr;
+  aerr = state_action_();
+  if (aerr != APIError::OK) {
+    return aerr;
+  }
+
+  if (state_ != State::DATA) {
+    return APIError::WOULD_BLOCK;
+  }
+
+  size_t padding = 0;
+  size_t msg_len = 4 + payload_len + padding;
+  size_t frame_len = 3 + msg_len + noise_cipherstate_get_mac_length(send_cipher_);
+  auto tmpbuf = std::unique_ptr<uint8_t[]>{new (std::nothrow) uint8_t[frame_len]};
+  if (tmpbuf == nullptr) {
+    HELPER_LOG("Could not allocate for writing packet");
+    return APIError::OUT_OF_MEMORY;
+  }
+
+  tmpbuf[0] = 0x01;  // indicator
+  // tmpbuf[1], tmpbuf[2] to be set later
+  const uint8_t msg_offset = 3;
+  const uint8_t payload_offset = msg_offset + 4;
+  tmpbuf[msg_offset + 0] = (uint8_t)(type >> 8);  // type
+  tmpbuf[msg_offset + 1] = (uint8_t) type;
+  tmpbuf[msg_offset + 2] = (uint8_t)(payload_len >> 8);  // data_len
+  tmpbuf[msg_offset + 3] = (uint8_t) payload_len;
+  // copy data
+  std::copy(payload, payload + payload_len, &tmpbuf[payload_offset]);
+  // fill padding with zeros
+  std::fill(&tmpbuf[payload_offset + payload_len], &tmpbuf[frame_len], 0);
+
+  NoiseBuffer mbuf;
+  noise_buffer_init(mbuf);
+  noise_buffer_set_inout(mbuf, &tmpbuf[msg_offset], msg_len, frame_len - msg_offset);
+  err = noise_cipherstate_encrypt(send_cipher_, &mbuf);
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_cipherstate_encrypt failed: %s", noise_err_to_str(err).c_str());
+    return APIError::CIPHERSTATE_ENCRYPT_FAILED;
+  }
+
+  size_t total_len = 3 + mbuf.size;
+  tmpbuf[1] = (uint8_t)(mbuf.size >> 8);
+  tmpbuf[2] = (uint8_t) mbuf.size;
+  // write raw to not have two packets sent if NAGLE disabled
+  aerr = write_raw_(&tmpbuf[0], total_len);
+  if (aerr != APIError::OK) {
+    return aerr;
+  }
+  return APIError::OK;
+}
+APIError APINoiseFrameHelper::try_send_tx_buf_() {
+  // try send from tx_buf
+  while (state_ != State::CLOSED && !tx_buf_.empty()) {
+    ssize_t sent = socket_->write(tx_buf_.data(), tx_buf_.size());
+    if (sent == -1) {
+      if (errno == EWOULDBLOCK || errno == EAGAIN)
+        break;
+      state_ = State::FAILED;
+      HELPER_LOG("Socket write failed with errno %d", errno);
+      return APIError::SOCKET_WRITE_FAILED;
+    } else if (sent == 0) {
+      break;
+    }
+    // TODO: inefficient if multiple packets in txbuf
+    // replace with deque of buffers
+    tx_buf_.erase(tx_buf_.begin(), tx_buf_.begin() + sent);
+  }
+
+  return APIError::OK;
+}
+/** Write the data to the socket, or buffer it a write would block
+ *
+ * @param data The data to write
+ * @param len The length of data
+ */
+APIError APINoiseFrameHelper::write_raw_(const uint8_t *data, size_t len) {
+  if (len == 0)
+    return APIError::OK;
+  int err;
+  APIError aerr;
+
+  // uncomment for even more debugging
+  // ESP_LOGVV(TAG, "Sending raw: %s", hexencode(data, len).c_str());
+
+  if (!tx_buf_.empty()) {
+    // try to empty tx_buf_ first
+    aerr = try_send_tx_buf_();
+    if (aerr != APIError::OK && aerr != APIError::WOULD_BLOCK)
+      return aerr;
+  }
+
+  if (!tx_buf_.empty()) {
+    // tx buf not empty, can't write now because then stream would be inconsistent
+    tx_buf_.insert(tx_buf_.end(), data, data + len);
+    return APIError::OK;
+  }
+
+  ssize_t sent = socket_->write(data, len);
+  if (is_would_block(sent)) {
+    // operation would block, add buffer to tx_buf
+    tx_buf_.insert(tx_buf_.end(), data, data + len);
+    return APIError::OK;
+  } else if (sent == -1) {
+    // an error occured
+    state_ = State::FAILED;
+    HELPER_LOG("Socket write failed with errno %d", errno);
+    return APIError::SOCKET_WRITE_FAILED;
+  } else if (sent != len) {
+    // partially sent, add end to tx_buf
+    tx_buf_.insert(tx_buf_.end(), data + sent, data + len);
+    return APIError::OK;
+  }
+  // fully sent
+  return APIError::OK;
+}
+APIError APINoiseFrameHelper::write_frame_(const uint8_t *data, size_t len) {
+  APIError aerr;
+
+  uint8_t header[3];
+  header[0] = 0x01;  // indicator
+  header[1] = (uint8_t)(len >> 8);
+  header[2] = (uint8_t) len;
+
+  aerr = write_raw_(header, 3);
+  if (aerr != APIError::OK)
+    return aerr;
+  aerr = write_raw_(data, len);
+  return aerr;
+}
+
+/** Initiate the data structures for the handshake.
+ *
+ * @return 0 on success, -1 on error (check errno)
+ */
+APIError APINoiseFrameHelper::init_handshake_() {
+  int err;
+  memset(&nid_, 0, sizeof(nid_));
+  // const char *proto = "Noise_NNpsk0_25519_ChaChaPoly_SHA256";
+  // err = noise_protocol_name_to_id(&nid_, proto, strlen(proto));
+  nid_.pattern_id = NOISE_PATTERN_NN;
+  nid_.cipher_id = NOISE_CIPHER_CHACHAPOLY;
+  nid_.dh_id = NOISE_DH_CURVE25519;
+  nid_.prefix_id = NOISE_PREFIX_STANDARD;
+  nid_.hybrid_id = NOISE_DH_NONE;
+  nid_.hash_id = NOISE_HASH_SHA256;
+  nid_.modifier_ids[0] = NOISE_MODIFIER_PSK0;
+
+  err = noise_handshakestate_new_by_id(&handshake_, &nid_, NOISE_ROLE_RESPONDER);
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_handshakestate_new_by_id failed: %s", noise_err_to_str(err).c_str());
+    return APIError::HANDSHAKESTATE_SETUP_FAILED;
+  }
+
+  const auto &psk = ctx_->get_psk();
+  err = noise_handshakestate_set_pre_shared_key(handshake_, psk.data(), psk.size());
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_handshakestate_set_pre_shared_key failed: %s", noise_err_to_str(err).c_str());
+    return APIError::HANDSHAKESTATE_SETUP_FAILED;
+  }
+
+  err = noise_handshakestate_set_prologue(handshake_, prologue_.data(), prologue_.size());
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_handshakestate_set_prologue failed: %s", noise_err_to_str(err).c_str());
+    return APIError::HANDSHAKESTATE_SETUP_FAILED;
+  }
+  // set_prologue copies it into handshakestate, so we can get rid of it now
+  prologue_ = {};
+
+  err = noise_handshakestate_start(handshake_);
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_handshakestate_start failed: %s", noise_err_to_str(err).c_str());
+    return APIError::HANDSHAKESTATE_SETUP_FAILED;
+  }
+  return APIError::OK;
+}
+
+APIError APINoiseFrameHelper::check_handshake_finished_() {
+  assert(state_ == State::HANDSHAKE);
+
+  int action = noise_handshakestate_get_action(handshake_);
+  if (action == NOISE_ACTION_READ_MESSAGE || action == NOISE_ACTION_WRITE_MESSAGE)
+    return APIError::OK;
+  if (action != NOISE_ACTION_SPLIT) {
+    state_ = State::FAILED;
+    HELPER_LOG("Bad action for handshake: %d", action);
+    return APIError::HANDSHAKESTATE_BAD_STATE;
+  }
+  int err = noise_handshakestate_split(handshake_, &send_cipher_, &recv_cipher_);
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("noise_handshakestate_split failed: %s", noise_err_to_str(err).c_str());
+    return APIError::HANDSHAKESTATE_SPLIT_FAILED;
+  }
+
+  HELPER_LOG("Handshake complete!");
+  noise_handshakestate_free(handshake_);
+  handshake_ = nullptr;
+  state_ = State::DATA;
+  return APIError::OK;
+}
+
+APINoiseFrameHelper::~APINoiseFrameHelper() {
+  if (handshake_ != nullptr) {
+    noise_handshakestate_free(handshake_);
+    handshake_ = nullptr;
+  }
+  if (send_cipher_ != nullptr) {
+    noise_cipherstate_free(send_cipher_);
+    send_cipher_ = nullptr;
+  }
+  if (recv_cipher_ != nullptr) {
+    noise_cipherstate_free(recv_cipher_);
+    recv_cipher_ = nullptr;
+  }
+}
+
+APIError APINoiseFrameHelper::close() {
+  state_ = State::CLOSED;
+  int err = socket_->close();
+  if (err == -1)
+    return APIError::CLOSE_FAILED;
+  return APIError::OK;
+}
+APIError APINoiseFrameHelper::shutdown(int how) {
+  int err = socket_->shutdown(how);
+  if (err == -1)
+    return APIError::SHUTDOWN_FAILED;
+  if (how == SHUT_RDWR) {
+    state_ = State::CLOSED;
+  }
+  return APIError::OK;
+}
+extern "C" {
+// declare how noise generates random bytes (here with a good HWRNG based on the RF system)
+void noise_rand_bytes(void *output, size_t len) { esphome::fill_random(reinterpret_cast<uint8_t *>(output), len); }
+}
+#endif  // USE_API_NOISE
+
+#ifdef USE_API_PLAINTEXT
+
 /// Initialize the frame helper, returns OK if successful.
 APIError APIPlaintextFrameHelper::init() {
   if (state_ != State::INITIALIZE || socket_ == nullptr) {
@@ -289,6 +900,7 @@ APIError APIPlaintextFrameHelper::shutdown(int how) {
   }
   return APIError::OK;
 }
+#endif  // USE_API_PLAINTEXT
 
 }  // namespace api
 }  // namespace esphome

esphome/components/api/api_frame_helper.h

@@ -5,7 +5,12 @@
 
 #include "esphome/core/defines.h"
 
+#ifdef USE_API_NOISE
+#include "noise/protocol.h"
+#endif
+
 #include "esphome/components/socket/socket.h"
+#include "api_noise_context.h"
 
 namespace esphome {
 namespace api {
@@ -27,6 +32,7 @@ struct PacketBuffer {
 enum class APIError : int {
   OK = 0,
   WOULD_BLOCK = 1001,
+  BAD_HANDSHAKE_PACKET_LEN = 1002,
   BAD_INDICATOR = 1003,
   BAD_DATA_PACKET = 1004,
   TCP_NODELAY_FAILED = 1005,
@@ -37,7 +43,14 @@ enum class APIError : int {
   BAD_ARG = 1010,
   SOCKET_READ_FAILED = 1011,
   SOCKET_WRITE_FAILED = 1012,
+  HANDSHAKESTATE_READ_FAILED = 1013,
+  HANDSHAKESTATE_WRITE_FAILED = 1014,
+  HANDSHAKESTATE_BAD_STATE = 1015,
+  CIPHERSTATE_DECRYPT_FAILED = 1016,
+  CIPHERSTATE_ENCRYPT_FAILED = 1017,
   OUT_OF_MEMORY = 1018,
+  HANDSHAKESTATE_SETUP_FAILED = 1019,
+  HANDSHAKESTATE_SPLIT_FAILED = 1020,
 };
 
 class APIFrameHelper {
@@ -53,6 +66,68 @@ class APIFrameHelper {
   // Give this helper a name for logging
   virtual void set_log_info(std::string info) = 0;
 };
+
+#ifdef USE_API_NOISE
+class APINoiseFrameHelper : public APIFrameHelper {
+ public:
+  APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, std::shared_ptr<APINoiseContext> ctx)
+      : socket_(std::move(socket)), ctx_(ctx) {}
+  ~APINoiseFrameHelper();
+  APIError init() override;
+  APIError loop() override;
+  APIError read_packet(ReadPacketBuffer *buffer) override;
+  bool can_write_without_blocking() override;
+  APIError write_packet(uint16_t type, const uint8_t *payload, size_t len) override;
+  std::string getpeername() override { return socket_->getpeername(); }
+  APIError close() override;
+  APIError shutdown(int how) override;
+  // Give this helper a name for logging
+  void set_log_info(std::string info) override { info_ = std::move(info); }
+
+ protected:
+  struct ParsedFrame {
+    std::vector<uint8_t> msg;
+  };
+
+  APIError state_action_();
+  APIError try_read_frame_(ParsedFrame *frame);
+  APIError try_send_tx_buf_();
+  APIError write_frame_(const uint8_t *data, size_t len);
+  APIError write_raw_(const uint8_t *data, size_t len);
+  APIError init_handshake_();
+  APIError check_handshake_finished_();
+  void send_explicit_handshake_reject_(const std::string &reason);
+
+  std::unique_ptr<socket::Socket> socket_;
+
+  std::string info_;
+  uint8_t rx_header_buf_[3];
+  size_t rx_header_buf_len_ = 0;
+  std::vector<uint8_t> rx_buf_;
+  size_t rx_buf_len_ = 0;
+
+  std::vector<uint8_t> tx_buf_;
+  std::vector<uint8_t> prologue_;
+
+  std::shared_ptr<APINoiseContext> ctx_;
+  NoiseHandshakeState *handshake_ = nullptr;
+  NoiseCipherState *send_cipher_ = nullptr;
+  NoiseCipherState *recv_cipher_ = nullptr;
+  NoiseProtocolId nid_;
+
+  enum class State {
+    INITIALIZE = 1,
+    CLIENT_HELLO = 2,
+    SERVER_HELLO = 3,
+    HANDSHAKE = 4,
+    DATA = 5,
+    CLOSED = 6,
+    FAILED = 7,
+  } state_ = State::INITIALIZE;
+};
+#endif  // USE_API_NOISE
+
+#ifdef USE_API_PLAINTEXT
 class APIPlaintextFrameHelper : public APIFrameHelper {
  public:
   APIPlaintextFrameHelper(std::unique_ptr<socket::Socket> socket) : socket_(std::move(socket)) {}
@@ -98,6 +173,7 @@ class APIPlaintextFrameHelper : public APIFrameHelper {
     FAILED = 4,
   } state_ = State::INITIALIZE;
 };
+#endif
 
 }  // namespace api
 }  // namespace esphome

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

esphome/components/api/api_server.h

@@ -11,6 +11,7 @@
 #include "list_entities.h"
 #include "subscribe_state.h"
 #include "user_services.h"
+#include "api_noise_context.h"
 
 namespace esphome {
 namespace api {
@@ -30,6 +31,11 @@ class APIServer : public Component, public Controller {
   void set_password(const std::string &password);
   void set_reboot_timeout(uint32_t reboot_timeout);
 
+#ifdef USE_API_NOISE
+  void set_noise_psk(psk_t psk) { noise_ctx_->set_psk(std::move(psk)); }
+  std::shared_ptr<APINoiseContext> get_noise_ctx() { return noise_ctx_; }
+#endif  // USE_API_NOISE
+
   void handle_disconnect(APIConnection *conn);
 #ifdef USE_BINARY_SENSOR
   void on_binary_sensor_update(binary_sensor::BinarySensor *obj, bool state) override;
@@ -89,6 +95,10 @@ class APIServer : public Component, public Controller {
   std::string password_;
   std::vector<HomeAssistantStateSubscription> state_subs_;
   std::vector<UserServiceDescriptor *> user_services_;
+
+#ifdef USE_API_NOISE
+  std::shared_ptr<APINoiseContext> noise_ctx_ = std::make_shared<APINoiseContext>();
+#endif  // USE_API_NOISE
 };
 
 extern APIServer *global_api_server;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)

esphome/core/defines.h

@@ -54,5 +54,8 @@
 #define USE_SOCKET_IMPL_BSD_SOCKETS
 #endif
 
+#define USE_API_PLAINTEXT
+#define USE_API_NOISE
+
 // Disabled feature flags
 //#define USE_BSEC  // Requires a library with proprietary license.

esphome/core/helpers.cpp

@@ -55,6 +55,15 @@ double random_double() { return random_uint32() / double(UINT32_MAX); }
 
 float random_float() { return float(random_double()); }
 
+void fill_random(uint8_t *data, size_t len) {
+#ifdef ARDUINO_ARCH_ESP32
+  esp_fill_random(data, len);
+#else
+  int err = os_get_random(data, len);
+  assert(err == 0);
+#endif
+}
+
 static uint32_t fast_random_seed = 0;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
 void fast_random_set_seed(uint32_t seed) { fast_random_seed = seed; }

esphome/core/helpers.h

@@ -109,6 +109,8 @@ double random_double();
 /// Returns a random float between 0 and 1. Essentially just casts random_double() to a float.
 float random_float();
 
+void fill_random(uint8_t *data, size_t len);
+
 void fast_random_set_seed(uint32_t seed);
 uint32_t fast_random_32();
 uint16_t fast_random_16();

platformio.ini

@@ -36,6 +36,7 @@ lib_deps =
     6306@1.0.3  ; HM3301
     glmnet/Dsmr@0.3        ; used by dsmr
     rweather/Crypto@0.2.0  ; used by dsmr
+    esphome/noise-c@0.1.1  ; used by api
     dudanov/MideaUART@1.1.0  ; used by midea
 
 build_flags =

tests/test3.yaml

@@ -22,6 +22,8 @@ api:
   port: 8000
   password: 'pwd'
   reboot_timeout: 0min
+  encryption:
+    key: 'bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU='
   services:
     - service: hello_world
       variables: