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Merge pull request #32 from screentinker/fix/android-device-fixes

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fix(android): OTA APK signature verification (Critical) + pairing-code visibility
This commit is contained in:
screentinker 2026-06-08 20:08:58 -05:00 committed by GitHub
parent 50ad1f670b 60cda97b1d
commit 171b69233c
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
4 changed files with 203 additions and 105 deletions
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2
android/app/src/main/AndroidManifest.xml
View file

@ -17,7 +17,7 @@
<application
android:name=".RemoteDisplayApp"
android:allowBackup="true"
android:allowBackup="false"
android:icon="@android:drawable/ic_media_play"
android:label="RemoteDisplay"
android:largeHeap="true"

10
android/app/src/main/java/com/remotedisplay/player/ProvisioningActivity.kt
View file

@ -34,6 +34,7 @@ class ProvisioningActivity : AppCompatActivity() {
private lateinit var statusText: TextView
private lateinit var progressBar: ProgressBar
private lateinit var pairingSection: View
private lateinit var serverSection: View
private val connection = object : ServiceConnection {
override fun onServiceConnected(name: ComponentName?, service: IBinder?) {
@ -73,6 +74,7 @@ class ProvisioningActivity : AppCompatActivity() {
statusText = findViewById(R.id.statusText)
progressBar = findViewById(R.id.progressBar)
pairingSection = findViewById(R.id.pairingSection)
serverSection = findViewById(R.id.serverSection)
// Pre-fill if previously entered
if (config.serverUrl.isNotEmpty()) {
@ -135,9 +137,15 @@ class ProvisioningActivity : AppCompatActivity() {
wsService?.onRegistered = { deviceId ->
runOnUiThread {
progressBar.visibility = View.GONE
// Hide the server/connect controls so the pairing code has the
// whole screen and stays visible on short/landscape phones.
serverSection.visibility = View.GONE
connectBtn.visibility = View.GONE
pairingSection.visibility = View.VISIBLE
pairingCodeText.text = wsService?.getPairingCode() ?: "------"
statusText.text = "Enter this code in the dashboard to pair this display"
// The instruction is shown once, inside the pairing section; don't
// duplicate it in statusText.
statusText.text = ""
connectBtn.isEnabled = false
}
}

68
android/app/src/main/java/com/remotedisplay/player/service/UpdateChecker.kt
View file

@ -5,6 +5,9 @@ import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.content.pm.PackageInfo
import android.content.pm.PackageManager
import android.content.pm.Signature
import android.net.Uri
import android.os.Build
import android.os.Environment
@ -17,6 +20,7 @@ import okhttp3.OkHttpClient
import okhttp3.Request
import org.json.JSONObject
import java.io.File
import java.security.MessageDigest
import java.util.concurrent.TimeUnit
class UpdateChecker(private val context: Context) {
@ -107,6 +111,20 @@ class UpdateChecker(private val context: Context) {
Log.i(TAG, "APK downloaded: ${apkFile.absolutePath} (${apkFile.length()} bytes)")
// SECURITY (#5 review): never install an APK we didn't sign. The update
// is fetched from a server-supplied URL, often over cleartext with no
// pinning - a MITM or compromised server could otherwise return a
// malicious APK and get it silently installed (REQUEST_INSTALL_PACKAGES).
// Verify the downloaded APK is our package AND signed by the same key as
// the currently-installed app before installing. An attacker can't forge
// our signature, so this holds even over an untrusted transport.
if (!verifyApkSignature(apkFile)) {
Log.e(TAG, "Refusing update: APK signature/package verification failed (tampered or MITM'd APK)")
apkFile.delete()
return
}
Log.i(TAG, "APK signature verified against installed app - proceeding to install")
// Install the APK
handler.post {
installApk(apkFile)
@ -179,6 +197,56 @@ class UpdateChecker(private val context: Context) {
}
}
// True only if the downloaded APK is this same package and shares a signing
// certificate with the installed app. Fail-closed on any error.
private fun verifyApkSignature(apkFile: File): Boolean {
return try {
val pm = context.packageManager
val flags = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P)
PackageManager.GET_SIGNING_CERTIFICATES else @Suppress("DEPRECATION") PackageManager.GET_SIGNATURES
val downloaded = pm.getPackageArchiveInfo(apkFile.absolutePath, flags)
if (downloaded == null) {
Log.e(TAG, "Could not parse downloaded APK")
return false
}
if (downloaded.packageName != context.packageName) {
Log.e(TAG, "APK package mismatch: ${downloaded.packageName} != ${context.packageName}")
return false
}
val installed = pm.getPackageInfo(context.packageName, flags)
val downloadedSigs = signingCertHashes(downloaded)
val installedSigs = signingCertHashes(installed)
if (downloadedSigs.isEmpty() || installedSigs.isEmpty()) {
Log.e(TAG, "Missing signing certificates (downloaded=${downloadedSigs.size}, installed=${installedSigs.size})")
return false
}
// Share at least one current signing certificate.
val match = downloadedSigs.any { it in installedSigs }
if (!match) Log.e(TAG, "APK signing certificate does not match installed app")
match
} catch (e: Exception) {
Log.e(TAG, "Signature verification error: ${e.message}", e)
false
}
}
private fun signingCertHashes(info: PackageInfo): Set<String> {
val sigs: Array<Signature>? = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
info.signingInfo?.apkContentsSigners
} else {
@Suppress("DEPRECATION") info.signatures
}
return sigs?.mapNotNull { sha256(it.toByteArray()) }?.toSet() ?: emptySet()
}
private fun sha256(bytes: ByteArray): String? {
return try {
MessageDigest.getInstance("SHA-256").digest(bytes).joinToString("") { "%02x".format(it) }
} catch (e: Exception) {
null
}
}
private fun getAppVersion(): String {
return try {
context.packageManager.getPackageInfo(context.packageName, 0).versionName ?: "1.0.0"

228
android/app/src/main/res/layout/activity_provisioning.xml
View file

@ -1,123 +1,145 @@
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
<!-- Scrolls so content is always reachable on short screens; the pairing code
auto-sizes to fit any screen width (phones, TVs, HD sticks). -->
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical"
android:background="#111827"
android:padding="48dp"
android:keepScreenOn="true">
android:fillViewport="true"
android:background="#111827">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="RemoteDisplay"
android:textColor="#3B82F6"
android:textSize="36sp"
android:textStyle="bold"
android:layout_marginBottom="8dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Digital Signage Player"
android:textColor="#94A3B8"
android:textSize="16sp"
android:layout_marginBottom="48dp" />
<!-- Server URL Section -->
<LinearLayout
android:layout_width="400dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal|top"
android:orientation="vertical"
android:layout_marginBottom="24dp">
android:paddingHorizontal="32dp"
android:paddingTop="24dp"
android:paddingBottom="24dp"
android:keepScreenOn="true">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Server URL"
android:textColor="#94A3B8"
android:textSize="14sp"
android:layout_marginBottom="8dp" />
<EditText
android:id="@+id/serverUrlInput"
android:layout_width="match_parent"
android:layout_height="48dp"
android:background="@drawable/input_background"
android:hint="http://192.168.1.100:3000"
android:textColorHint="#64748B"
android:textColor="#F1F5F9"
android:textSize="16sp"
android:padding="12dp"
android:inputType="textUri"
android:singleLine="true"
android:importantForAutofill="no" />
</LinearLayout>
<Button
android:id="@+id/connectBtn"
android:layout_width="400dp"
android:layout_height="48dp"
android:text="Connect"
android:textColor="#FFFFFF"
android:textSize="16sp"
android:textStyle="bold"
android:background="@drawable/button_primary"
android:layout_marginBottom="32dp" />
<ProgressBar
android:id="@+id/progressBar"
android:layout_width="48dp"
android:layout_height="48dp"
android:indeterminate="true"
android:visibility="gone" />
<!-- Pairing Section (shown after connection) -->
<LinearLayout
android:id="@+id/pairingSection"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center"
android:visibility="gone">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Pairing Code"
android:textColor="#94A3B8"
android:textSize="16sp"
android:layout_marginBottom="12dp" />
<TextView
android:id="@+id/pairingCodeText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="------"
android:text="RemoteDisplay"
android:textColor="#3B82F6"
android:textSize="64sp"
android:textSize="22sp"
android:textStyle="bold"
android:fontFamily="monospace"
android:letterSpacing="0.3" />
android:layout_marginBottom="4dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Enter this code in the dashboard to pair this display"
android:textColor="#64748B"
android:text="Digital Signage Player"
android:textColor="#94A3B8"
android:textSize="14sp"
android:layout_marginTop="16dp"
android:gravity="center" />
android:layout_marginBottom="20dp" />
<!-- Server URL Section (hidden once paired so the code has room) -->
<LinearLayout
android:id="@+id/serverSection"
android:layout_width="400dp"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginBottom="24dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Server URL"
android:textColor="#94A3B8"
android:textSize="14sp"
android:layout_marginBottom="8dp" />
<EditText
android:id="@+id/serverUrlInput"
android:layout_width="match_parent"
android:layout_height="48dp"
android:background="@drawable/input_background"
android:hint="http://192.168.1.100:3000"
android:textColorHint="#64748B"
android:textColor="#F1F5F9"
android:textSize="16sp"
android:padding="12dp"
android:inputType="textUri"
android:singleLine="true"
android:importantForAutofill="no" />
</LinearLayout>
<Button
android:id="@+id/connectBtn"
android:layout_width="400dp"
android:layout_height="48dp"
android:text="Connect"
android:textColor="#FFFFFF"
android:textSize="16sp"
android:textStyle="bold"
android:background="@drawable/button_primary"
android:layout_marginBottom="32dp" />
<ProgressBar
android:id="@+id/progressBar"
android:layout_width="48dp"
android:layout_height="48dp"
android:indeterminate="true"
android:visibility="gone" />
<!-- Pairing Section (shown after connection) -->
<LinearLayout
android:id="@+id/pairingSection"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center"
android:visibility="gone">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Pairing Code"
android:textColor="#94A3B8"
android:textSize="16sp"
android:layout_marginBottom="12dp" />
<!-- FIXED-height box: autosize fits the text inside the bounded box and
gravity center vertically centers it, so the digits are never
clipped (the earlier wrap_content height clipped the glyph bottoms).
24-64sp fills the width on phones/TVs/sticks. -->
<TextView
android:id="@+id/pairingCodeText"
android:layout_width="match_parent"
android:layout_height="96dp"
android:text="------"
android:textColor="#3B82F6"
android:textStyle="bold"
android:fontFamily="monospace"
android:letterSpacing="0.3"
android:maxLines="1"
android:gravity="center"
app:autoSizeTextType="uniform"
app:autoSizeMinTextSize="24sp"
app:autoSizeMaxTextSize="64sp"
app:autoSizeStepGranularity="2sp" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Enter this code in the dashboard to pair this display"
android:textColor="#64748B"
android:textSize="14sp"
android:layout_marginTop="16dp"
android:gravity="center" />
</LinearLayout>
<TextView
android:id="@+id/statusText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#94A3B8"
android:textSize="14sp"
android:gravity="center"
android:layout_marginTop="16dp" />
</LinearLayout>
<TextView
android:id="@+id/statusText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#94A3B8"
android:textSize="14sp"
android:layout_marginTop="16dp" />
</LinearLayout>
</ScrollView>