api/firmware: add option to skip noise pairing confirmation

api/firmware/device.go

@@ -108,6 +108,8 @@ type Device struct {
 	mu      sync.RWMutex
 	onEvent func(Event, interface{})
 	log     Logger
+
+	options *deviceOptions
 }
 
 // BluetoothInfo contains Bluetooth-related info.
@@ -144,17 +146,23 @@ func NewDevice(
 	config ConfigInterface,
 	communication Communication,
 	log Logger,
+	opts ...DeviceOption,
 ) *Device {
 	if (version == nil) != (product == nil) {
 		panic("both version and product have to be specified, or none")
 	}
+	options := &deviceOptions{}
+	for _, opt := range opts {
+		opt(options)
+	}
 	return &Device{
 		communication: communication,
 		version:       version,
 		product:       product,
 		config:        config,
 		status:        StatusConnected,
 		log:           log,
+		options:       options,
 	}
 }
 

api/firmware/options.go

@@ -0,0 +1,35 @@
+// Copyright 2025 Shift Crypto AG
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package firmware
+
+type deviceOptions struct {
+	// If true, the host does not require noise pairing confirmation before communicating over the
+	// encrypted noise channel.
+	optionalNoisePairingConfirmation bool
+}
+
+// DeviceOption provides functional options.
+type DeviceOption func(*deviceOptions)
+
+// WithOptionalNoisePairingConfirmation allows the host to communicate over the encrypted noise
+// channel without requiring a pairing confirmation on the BitBox.
+//
+// SECURITY NOTE: this enables a MITM in the noise channel to go undetected. Use only if the noise
+// channel is wrapped in another secure transport layer, e.g. a paired Bluetooth connection.
+func WithOptionalNoisePairingConfirmation(optional bool) DeviceOption {
+	return func(o *deviceOptions) {
+		o.optionalNoisePairingConfirmation = optional
+	}
+}

api/firmware/pairing.go

@@ -101,8 +101,7 @@ func (device *Device) pair() error {
 		panic(errp.New("expected 32 byte remote static pubkey"))
 	}
 
-	pairingVerificationRequiredByApp := !device.config.ContainsDeviceStaticPubkey(
-		device.deviceNoiseStaticPubkey)
+	pairingVerificationRequiredByApp := !device.options.optionalNoisePairingConfirmation && !device.config.ContainsDeviceStaticPubkey(device.deviceNoiseStaticPubkey)
 	pairingVerificationRequiredByDevice := string(responseBytes) == "\x01"
 
 	if pairingVerificationRequiredByDevice || pairingVerificationRequiredByApp {