[ota] Add Noise encryption to the OTA platform (#18489)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
This commit is contained in:
J. Nick Koston
2026-09-02 08:11:57 +12:00
committed by GitHub
co-authored by Jesse Hills
parent 0aff9e1c54
commit 3f68930001
22 changed files with 1772 additions and 46 deletions
+35 -3
View File
@@ -23,7 +23,8 @@ For this repository there are two trusted inputs by design:
1. **The configuration.** Anyone who can supply or edit a YAML config is trusted
(see below).
2. **Authenticated peers of a running device** — clients holding the device's
API encryption key / password, OTA password, or web server credentials.
API/OTA encryption key, API password, OTA password, or web server
credentials.
The security boundary is therefore **unauthenticated network traffic vs. those
trusted inputs.** A bug that lets an unauthenticated attacker cross it is a
@@ -76,8 +77,8 @@ These *are* security bugs in this repo, and we want to hear about them privately
captive portal, etc.) **without** valid credentials.
- Authentication or encryption bypass on the device — reaching API calls, OTA
updates, or the web server without the configured key/password.
- Flaws that weaken the device's API encryption (Noise), OTA, or web server auth
below their documented guarantees.
- Flaws that weaken the device's API or OTA encryption (Noise), OTA auth, or
web server auth below their documented guarantees.
## The web server is an open HTTP API by design
@@ -121,6 +122,37 @@ and any memory-safety or protocol bug in the server reachable without credential
This section documents the current design and scope; it is not a judgment that the
design is optimal or that it will not change.
## OTA update encryption
The `esphome` OTA platform optionally encrypts updates with the same Noise
`NNpsk0` pattern the native API uses; one key protects the device. With an
`encryption:` block configured the guarantees are: the firmware image is
confidential in transit, the uploader is authenticated by the pre-shared key,
and the plaintext negotiation preceding the handshake is bound into the
handshake prologue, so stripping or tampering with it fails the first MAC.
Both ends fail closed with no override: a device built with a key refuses
plaintext uploads, and the CLI refuses to send plaintext when a key is
configured.
Defeating any of that without the key is in scope: a keyed device accepting a
plaintext or downgraded upload, getting past the MAC, or recovering image
contents from captured traffic.
The following are **not** vulnerabilities, by design:
- Plaintext OTA on a device with no `encryption:` block. That is the
documented default, authenticated (if at all) by the OTA password.
- The enablement window: turning encryption on takes one last upload of the
encryption-enabled firmware over the existing plaintext channel, with the
pre-existing plaintext exposure.
- The web OTA `/update` endpoint alongside encryption. The `web_server`
component keeps it always reachable, and `captive_portal:` auto-loads it
for the fallback AP window; validation warns about both combinations, and
the operator keeps the recovery path.
- CLI retry behavior on transport or MAC failures; every attempt renegotiates
a fresh handshake with fresh ephemerals, so retrying does not weaken
authentication.
## Explicitly out of scope
- Local attackers who already have shell access on the host that runs `esphome`.
+28 -1
View File
@@ -26,7 +26,9 @@ from esphome.const import (
CONF_DEASSERT_RTS_DTR,
CONF_DISABLED,
CONF_DISCOVER_IP,
CONF_ENCRYPTION,
CONF_ESPHOME,
CONF_KEY,
CONF_LEVEL,
CONF_LOG,
CONF_LOG_TOPIC,
@@ -1336,6 +1338,19 @@ def _upload_via_native_api(
remote_port = int(ota_conf[CONF_PORT])
password = ota_conf.get(CONF_PASSWORD)
# Fail closed: an encryption block whose key did not resolve must never
# fall back to a plaintext upload
noise_psk = None
if (encryption_conf := ota_conf.get(CONF_ENCRYPTION)) is not None:
noise_psk = encryption_conf.get(CONF_KEY)
if not noise_psk:
raise EsphomeError(
"OTA encryption is configured but no key was resolved; "
"set the key under 'ota: encryption:' or 'api: encryption:'"
)
# Ensure the key is a string, as required by the underlying OTA implementation.
# It arrives here as a SensitiveStr which aioesphomeapi rejects.
noise_psk = str(noise_psk)
def check_partition_access(option_string: str) -> None:
if not ota_conf.get("allow_partition_access"):
@@ -1366,7 +1381,9 @@ def _upload_via_native_api(
if ota_type == espota2.OTA_TYPE_UPDATE_BOOTLOADER:
_validate_bootloader_binary(binary)
return espota2.run_ota(network_devices, remote_port, password, binary, ota_type)
return espota2.run_ota(
network_devices, remote_port, password, binary, ota_type, noise_psk
)
def _upload_via_web_server(
@@ -1375,6 +1392,16 @@ def _upload_via_web_server(
from esphome import web_server_ota
from esphome.web_server_helpers import get_web_server_connection
if any(
ota_item.get(CONF_PLATFORM) == CONF_ESPHOME
and ota_item.get(CONF_ENCRYPTION) is not None
for ota_item in config.get(CONF_OTA, [])
):
_LOGGER.warning(
"This config has OTA encryption, but the web_server OTA path sends "
"the image over plaintext HTTP; use the esphome OTA platform to "
"keep it confidential"
)
remote_port, username, password = get_web_server_connection(config)
return web_server_ota.run_ota(
network_devices, remote_port, username, password, binary
File diff suppressed because it is too large Load Diff
File diff suppressed because it is too large Load Diff
+69 -1
View File
@@ -4,6 +4,9 @@
#ifdef USE_OTA
#include "esphome/components/ota/ota_backend_factory.h"
#include "esphome/components/socket/socket.h"
#ifdef USE_OTA_ENCRYPTION
#include "esphome/components/noise/noise_handshake.h"
#endif
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
#include "esphome/core/preferences.h"
@@ -24,7 +27,10 @@ class ESPHomeOTAComponent final : public ota::OTAComponent {
AUTH_SEND, // Sending authentication request
AUTH_READ, // Reading authentication data
#endif // USE_OTA_PASSWORD
DATA, // BLOCKING! Processing OTA data (update, etc.)
#ifdef USE_OTA_ENCRYPTION
NOISE_HANDSHAKE, // Exchanging Noise handshake frames
#endif
DATA, // BLOCKING! Processing OTA data (update, etc.)
};
#ifdef USE_OTA_PASSWORD
void set_auth_password(const std::string &password) { password_ = password; }
@@ -38,6 +44,10 @@ class ESPHomeOTAComponent final : public ota::OTAComponent {
}
#endif // USE_OTA_PASSWORD
#ifdef USE_OTA_ENCRYPTION
void set_noise_psk(noise::psk_t psk) { this->noise_ctx_.set_psk(psk); }
#endif
/// Manually set the port OTA should listen on
void set_port(uint16_t port) { this->port_ = port; }
@@ -63,6 +73,48 @@ class ESPHomeOTAComponent final : public ota::OTAComponent {
bool writeall_(const uint8_t *buf, size_t len);
inline bool write_byte_(uint8_t byte) { return this->writeall_(&byte, 1); }
#ifdef USE_OTA_ENCRYPTION
// Heap-allocated only while an encrypted OTA session is active.
struct NoiseSession {
~NoiseSession();
noise::NoiseResponderHandshake handshake;
NoiseCipherState *send_cipher{nullptr};
NoiseCipherState *recv_cipher{nullptr};
uint16_t frame_len{0}; // total frame size once the header is parsed, 0 until then
uint16_t frame_pos{0}; // bytes read or written so far
bool writing{false}; // a produced handshake frame is still being flushed
uint8_t frame_buf[noise::FRAME_HEADER_SIZE + 1 + noise::MAX_HANDSHAKE_SIZE];
};
bool noise_start_session_(uint8_t server_feature_flags);
bool handle_noise_handshake_();
bool noise_try_read_frame_();
bool noise_try_write_frame_();
void noise_send_reject_(const LogString *reason);
ssize_t noise_decrypt_(uint8_t *buf, size_t len);
ssize_t noise_read_frame_blocking_(uint8_t *buf, size_t min_ciphertext, size_t max_ciphertext);
bool noise_readall_(uint8_t *buf, size_t len);
ssize_t noise_read_data_(uint8_t *buf, size_t capacity);
bool noise_write_byte_(uint8_t byte);
#endif // USE_OTA_ENCRYPTION
// Data-phase I/O dispatch: through the noise transport when a session is
// active, straight to the socket otherwise.
inline bool data_write_byte_(uint8_t byte) {
#ifdef USE_OTA_ENCRYPTION
if (this->noise_ != nullptr)
return this->noise_write_byte_(byte);
#endif
return this->write_byte_(byte);
}
// When encrypted, buf must have room for len + noise::MAC_SIZE bytes.
inline bool data_readall_(uint8_t *buf, size_t len) {
#ifdef USE_OTA_ENCRYPTION
if (this->noise_ != nullptr)
return this->noise_readall_(buf, len);
#endif
return this->readall_(buf, len);
}
bool try_read_(size_t to_read, const LogString *desc);
bool try_write_(size_t to_write, const LogString *desc);
@@ -91,6 +143,10 @@ class ESPHomeOTAComponent final : public ota::OTAComponent {
std::string password_;
std::unique_ptr<uint8_t[]> auth_buf_;
#endif // USE_OTA_PASSWORD
#ifdef USE_OTA_ENCRYPTION
noise::NoiseContext noise_ctx_;
std::unique_ptr<NoiseSession> noise_;
#endif // USE_OTA_ENCRYPTION
socket::ListenSocket *server_{nullptr};
std::unique_ptr<socket::Socket> client_;
@@ -98,6 +154,18 @@ class ESPHomeOTAComponent final : public ota::OTAComponent {
uint32_t client_connect_time_{0};
static constexpr size_t HANDSHAKE_BUF_SIZE = 5;
// Buffer size for OTA data transfer. The upload client derives its maximum
// encrypted frame plaintext from this (espota2.NOISE_MAX_PLAINTEXT is this
// minus the 16-byte MAC); both must change together.
static constexpr size_t OTA_BUFFER_SIZE = 1040;
#ifdef USE_OTA_ENCRYPTION
// espota2.NOISE_MAX_PLAINTEXT; shrinking the buffer would reject every
// frame a current CLI sends
static constexpr size_t NOISE_CLIENT_MAX_PLAINTEXT = 1024;
static_assert(OTA_BUFFER_SIZE >= NOISE_CLIENT_MAX_PLAINTEXT + noise::MAC_SIZE,
"OTA_BUFFER_SIZE must fit a full encrypted data frame");
#endif
static constexpr uint8_t MAGIC_BYTES[5] = {0x6C, 0x26, 0xF7, 0x5C, 0x45};
#ifdef USE_OTA_PARTITIONS
uint32_t running_app_offset_{0};
size_t running_app_size_{0};
File diff suppressed because it is too large Load Diff
+9
View File
@@ -45,6 +45,15 @@ def decode_encryption_key(value: str) -> bytes:
return decoded
def is_reserved_key(value: str) -> bool:
"""Whether the key is the reserved all-zeros provisioning sentinel.
The device treats it as no key configured, so consumers that require a
real key must reject it.
"""
return not any(decode_encryption_key(value))
ENCRYPTION_SCHEMA = cv.Schema(
{
cv.Optional(CONF_KEY): cv.sensitive(validate_encryption_key),
+1
View File
@@ -49,6 +49,7 @@ enum OTAResponseTypes {
OTA_RESPONSE_ERROR_BOOTLOADER_VERIFY = 0x91,
OTA_RESPONSE_ERROR_BOOTLOADER_UPDATE = 0x92,
OTA_RESPONSE_ERROR_VERSION_DOWNGRADE = 0x93,
OTA_RESPONSE_ERROR_ENCRYPTION_REQUIRED = 0x94,
OTA_RESPONSE_ERROR_UNKNOWN = 0xFF,
};
+1
View File
@@ -242,6 +242,7 @@
#define USE_RUNTIME_IMAGE_QOI
#define USE_RUNTIME_STATS
#define USE_OTA
#define USE_OTA_ENCRYPTION
#define USE_OTA_PASSWORD
#define USE_OTA_VERSION 2
#define USE_TIME_TIMEZONE
+193 -5
View File
File diff suppressed because it is too large Load Diff
@@ -5,7 +5,11 @@ from __future__ import annotations
import pytest
from esphome import config_validation as cv
from esphome.components.noise import decode_encryption_key, validate_encryption_key
from esphome.components.noise import (
decode_encryption_key,
is_reserved_key,
validate_encryption_key,
)
KEY = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
@@ -35,3 +39,8 @@ def test_decode_encryption_key_rejects_short_decode() -> None:
a zero padded PSK on the device."""
with pytest.raises(cv.Invalid, match="32 bytes"):
decode_encryption_key("AAECAw==")
def test_is_reserved_key() -> None:
assert is_reserved_key("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=")
assert not is_reserved_key(KEY)
File diff suppressed because it is too large Load Diff
+9
View File
@@ -0,0 +1,9 @@
wifi:
ssid: MySSID
password: password1
ota:
- platform: esphome
port: 3288
encryption:
key: "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
@@ -0,0 +1,12 @@
wifi:
ssid: MySSID
password: password1
api:
encryption:
key: "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
ota:
- platform: esphome
port: 3289
encryption:
@@ -0,0 +1,2 @@
packages:
ota: !include encryption.yaml
@@ -0,0 +1,2 @@
packages:
ota: !include encryption.yaml
@@ -0,0 +1,2 @@
packages:
ota: !include encryption.yaml
@@ -0,0 +1,2 @@
packages:
ota: !include encryption_inherit.yaml
@@ -0,0 +1,11 @@
esphome:
name: host-ota-test
host:
api:
ota:
- platform: esphome
port: __OTA_PORT__
encryption:
key: "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
logger:
level: DEBUG
+57
View File
@@ -10,6 +10,7 @@ from __future__ import annotations
import asyncio
from collections.abc import Generator
from contextlib import contextmanager
import functools
import socket
import pytest
@@ -111,6 +112,62 @@ async def test_host_ota_self_update(
assert proc.pid == pid_before
@pytest.mark.asyncio
async def test_host_ota_encrypted(
yaml_config: str,
write_yaml_config: ConfigWriter,
compile_esphome: CompileFunction,
reserved_tcp_port: tuple[int, socket.socket],
) -> None:
"""Encrypted self-OTA succeeds; a plaintext upload to the same device fails."""
pytest.importorskip("aioesphomeapi.noise")
noise_psk = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
api_port, api_socket = reserved_tcp_port
with _reserve_port() as (ota_port, ota_socket):
yaml_config = yaml_config.replace("__OTA_PORT__", str(ota_port))
config_path = await write_yaml_config(yaml_config)
binary_path = await compile_esphome(config_path)
api_socket.close()
ota_socket.close()
loop = asyncio.get_running_loop()
rebooted = loop.create_future()
def on_log(line: str) -> None:
if not rebooted.done() and "Rebooting safely" in line:
rebooted.set_result(True)
async with run_binary(binary_path, line_callback=on_log) as (proc, _lines):
await _wait_for_port(LOCALHOST, api_port, PORT_WAIT_TIMEOUT)
pid_before = proc.pid
# A plaintext upload must be refused with the device unharmed
rc, _ = await loop.run_in_executor(
None, espota2.run_ota, LOCALHOST, ota_port, None, binary_path
)
assert rc == 1, "plaintext upload to an encrypted device must fail"
await asyncio.sleep(0.5)
assert proc.returncode is None, "process died on rejected plaintext OTA"
# The encrypted upload goes through and the device re-execs
rc, _ = await loop.run_in_executor(
None,
functools.partial(
espota2.run_ota,
LOCALHOST,
ota_port,
None,
binary_path,
noise_psk=noise_psk,
),
)
assert rc == 0, "encrypted OTA reported failure"
await asyncio.wait_for(rebooted, timeout=10.0)
await _wait_for_port(LOCALHOST, api_port, PORT_WAIT_TIMEOUT)
assert proc.returncode is None, "process exited instead of execing"
assert proc.pid == pid_before
@pytest.mark.asyncio
async def test_host_ota_rejects_garbage(
yaml_config: str,
File diff suppressed because it is too large Load Diff
+103 -5
View File
@@ -86,7 +86,9 @@ from esphome.const import (
CONF_BROKER,
CONF_DISABLED,
CONF_DISCOVER_IP,
CONF_ENCRYPTION,
CONF_ESPHOME,
CONF_KEY,
CONF_LEVEL,
CONF_LOG,
CONF_LOG_TOPIC,
@@ -2106,10 +2108,65 @@ def test_upload_program_ota_success(
tmp_path / ".esphome" / "build" / "test" / ".pioenvs" / "test" / "firmware.bin"
)
mock_run_ota.assert_called_once_with(
["192.168.1.100"], 3232, "secret", expected_firmware, OTA_TYPE_UPDATE_APP
["192.168.1.100"], 3232, "secret", expected_firmware, OTA_TYPE_UPDATE_APP, None
)
def test_upload_program_ota_encryption_key(
mock_run_ota: Mock,
mock_get_port_type: Mock,
tmp_path: Path,
) -> None:
"""The resolved encryption key is passed through to run_ota."""
setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path)
mock_get_port_type.return_value = "NETWORK"
mock_run_ota.return_value = (0, "192.168.1.100")
key = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
config = {
CONF_OTA: [
{
CONF_PLATFORM: CONF_ESPHOME,
CONF_PORT: 3232,
CONF_ENCRYPTION: {CONF_KEY: key},
}
]
}
exit_code, host = upload_program(config, MockArgs(), ["192.168.1.100"])
assert exit_code == 0
assert host == "192.168.1.100"
expected_firmware = (
tmp_path / ".esphome" / "build" / "test" / ".pioenvs" / "test" / "firmware.bin"
)
mock_run_ota.assert_called_once_with(
["192.168.1.100"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP, key
)
def test_upload_program_ota_encryption_without_key_fails_closed(
mock_run_ota: Mock,
mock_get_port_type: Mock,
tmp_path: Path,
) -> None:
"""An encryption block with no resolved key must never upload plaintext."""
setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path)
mock_get_port_type.return_value = "NETWORK"
config = {
CONF_OTA: [
{
CONF_PLATFORM: CONF_ESPHOME,
CONF_PORT: 3232,
CONF_ENCRYPTION: {},
}
]
}
with pytest.raises(EsphomeError, match="no key was resolved"):
upload_program(config, MockArgs(), ["192.168.1.100"])
mock_run_ota.assert_not_called()
def test_upload_program_ota_with_file_arg(
mock_run_ota: Mock,
mock_get_port_type: Mock,
@@ -2137,7 +2194,7 @@ def test_upload_program_ota_with_file_arg(
assert exit_code == 0
assert host == "192.168.1.100"
mock_run_ota.assert_called_once_with(
["192.168.1.100"], 3232, None, Path("custom.bin"), OTA_TYPE_UPDATE_APP
["192.168.1.100"], 3232, None, Path("custom.bin"), OTA_TYPE_UPDATE_APP, None
)
@@ -2192,6 +2249,7 @@ def test_upload_program_ota_partition_table_with_file_arg(
None,
partition_file,
OTA_TYPE_UPDATE_PARTITION_TABLE,
None,
)
@@ -2253,6 +2311,7 @@ def test_upload_program_ota_partition_table_mqttip(
None,
partition_file,
OTA_TYPE_UPDATE_PARTITION_TABLE,
None,
)
@@ -2440,6 +2499,7 @@ def test_upload_program_ota_bootloader_with_file_arg(
None,
bootloader_file,
OTA_TYPE_UPDATE_BOOTLOADER,
None,
)
@@ -2602,6 +2662,42 @@ def test_has_web_server_logging_respects_log_disabled() -> None:
assert has_web_server_logging() is False
def test_upload_program_web_server_warns_when_encryption_configured(
mock_run_web_server_ota: Mock,
mock_run_ota: Mock,
mock_get_port_type: Mock,
tmp_path: Path,
caplog: pytest.LogCaptureFixture,
) -> None:
"""Explicitly picking web_server OTA on an encrypted config warns about
the plaintext upload path."""
setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path)
mock_get_port_type.return_value = "NETWORK"
mock_run_web_server_ota.return_value = (0, "192.168.1.100")
config = {
CONF_OTA: [
{
CONF_PLATFORM: CONF_ESPHOME,
CONF_PORT: 3232,
CONF_ENCRYPTION: {CONF_KEY: "test_key"},
},
{CONF_PLATFORM: CONF_WEB_SERVER},
],
CONF_WEB_SERVER: {
CONF_PORT: 80,
CONF_AUTH: {CONF_USERNAME: "admin", CONF_PASSWORD: "pw"},
},
}
args = MockArgs(ota_platform=CONF_WEB_SERVER)
with caplog.at_level(logging.WARNING):
exit_code, _ = upload_program(config, args, ["192.168.1.100"])
assert exit_code == 0
assert any("plaintext HTTP" in record.message for record in caplog.records)
mock_run_ota.assert_not_called()
def test_upload_program_web_server_only_auto_dispatches(
mock_run_web_server_ota: Mock,
mock_run_ota: Mock,
@@ -2892,7 +2988,7 @@ def test_upload_program_ota_with_mqtt_resolution(
tmp_path / ".esphome" / "build" / "test" / ".pioenvs" / "test" / "firmware.bin"
)
mock_run_ota.assert_called_once_with(
["192.168.1.100"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP
["192.168.1.100"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP, None
)
@@ -2942,7 +3038,7 @@ def test_upload_program_ota_with_mqtt_empty_broker(
tmp_path / ".esphome" / "build" / "test" / ".pioenvs" / "test" / "firmware.bin"
)
mock_run_ota.assert_called_once_with(
["192.168.1.50"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP
["192.168.1.50"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP, None
)
# Verify warning was logged
assert "MQTT IP discovery failed" in caplog.text
@@ -5114,6 +5210,7 @@ def test_upload_program_ota_static_ip_with_mqttip(
None,
expected_firmware,
OTA_TYPE_UPDATE_APP,
None,
)
@@ -5163,6 +5260,7 @@ def test_upload_program_ota_multiple_mqttip_resolves_once(
None,
expected_firmware,
OTA_TYPE_UPDATE_APP,
None,
)
@@ -5340,7 +5438,7 @@ def test_upload_program_ota_mqtt_timeout_fallback(
tmp_path / ".esphome" / "build" / "test" / ".pioenvs" / "test" / "firmware.bin"
)
mock_run_ota.assert_called_once_with(
["192.168.1.100"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP
["192.168.1.100"], 3232, None, expected_firmware, OTA_TYPE_UPDATE_APP, None
)