Fixes watch face release obfuscation and optimization issues

watchface/README.md

@@ -21,10 +21,4 @@ example, using `pngquant` on all images, to help keep the watch face size to a m
 
 To package the watch face, the [Pack](https://github.com/google/pack) is used. This is a native
 library, so the pre-builts are provided in `jniLibs`. A script is also included for building these
-fresh, but that should not be necessary.
-
-## Signing the APK
-
-For the purposes of this project, a key is generated at runtime and used to sign the APK. This is
-not the approach to take in production, but the watch face APK must be signed, and it doesn't so
-much matter what key is used to do it.
+fresh, but that should not be necessary.

watchface/build.gradle.kts

@@ -30,8 +30,11 @@ android {
         minSdk = libs.versions.minSdk.get().toInt()
         targetSdk = 36
         testInstrumentationRunner = "com.android.developers.testing.AndroidifyTestRunner"
+        consumerProguardFiles("proguard-rules.pro")
+    }
+    buildFeatures {
+        buildConfig = true
     }
-
     compileOptions {
         sourceCompatibility = JavaVersion.toVersion(libs.versions.javaVersion.get())
         targetCompatibility = JavaVersion.toVersion(libs.versions.javaVersion.get())

watchface/proguard-rules.pro

@@ -6,4 +6,29 @@
 -dontwarn org.eclipse.wst.xml.xpath2.processor.**
 
 # Ignore missing Java SE annotation processing classes, often from libraries like AutoValue/JavaPoet
--dontwarn javax.lang.model.**
+-dontwarn javax.lang.model.**
+
+-keep class com.android.developers.androidify.watchface.creator.PackPackage {
+    native <methods>;
+}
+
+-keep class com.android.developers.androidify.watchface.creator.PackPackage$Resource { *; }
+
+# Keep all classes in the BouncyCastle provider, as they are loaded via reflection
+-keep class org.bouncycastle.** { *; }
+-keep interface org.bouncycastle.** { *; }
+
+# Keep the APK Signer library
+-keep class com.android.apksig.** { *; }
+-keep interface com.android.apksig.** { *; }
+
+# Keep Apache Xerces XML parser
+-keep class org.apache.xerces.** { *; }
+
+## Keep standard Java XML (JAXP), DOM, and SAX interfaces and classes
+-keep interface org.w3c.dom.** { *; }
+-keep class org.w3c.dom.** { *; }
+-keep interface org.xml.sax.** { *; }
+-keep class org.xml.sax.** { *; }
+-keep class javax.xml.** { *; }
+-keep interface javax.xml.** { *; }

watchface/src/main/java/com/android/developers/androidify/watchface/creator/PackPackage.kt

@@ -24,9 +24,9 @@ data class PackPackage(
     var resources: MutableList<Resource> = mutableListOf()
 
     data class Resource(
-        val subdirectory: String,
-        val name: String,
-        val contentsBase64: String,
+        @JvmField val subdirectory: String,
+        @JvmField val name: String,
+        @JvmField val contentsBase64: String,
     ) {
         companion object {
             fun fromBase64Contents(

watchface/src/main/java/com/android/developers/androidify/watchface/creator/Signer.kt

@@ -23,6 +23,7 @@ import com.android.apksig.util.DataSink
 import com.android.apksig.util.DataSource
 import com.android.apksig.util.DataSources
 import com.android.apksig.util.ReadableDataSink
+import com.android.developers.androidify.watchface.BuildConfig
 import org.bouncycastle.asn1.x500.X500Name
 import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter
 import org.bouncycastle.cert.jcajce.JcaX509v3CertificateBuilder
@@ -38,8 +39,10 @@ import java.security.cert.X509Certificate
 import java.util.Calendar
 import java.util.Date
 
-private const val KEY_ALIAS = "com.android.developers.androidify.ApkSigningKey"
-private const val CERT_ALIAS = "com.android.developers.androidify.Cert"
+private val keyAlias : String
+    get() = "com.android.developers.androidify.ApkSigningKey-" + BuildConfig.BUILD_TYPE
+private val certAlias: String
+    get() = "com.android.developers.androidify.Cert-" + BuildConfig.BUILD_TYPE
 private const val ANDROID_KEYSTORE = "AndroidKeyStore"
 
 /**
@@ -71,13 +74,13 @@ fun signApk(unsignedApk: ByteArray): ByteArray {
 private fun getOrCreateSigningKeyPair(): KeyPair {
     val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE).apply { load(null) }
 
-    if (keyStore.containsAlias(KEY_ALIAS)) {
-        val entry = keyStore.getEntry(KEY_ALIAS, null) as KeyStore.PrivateKeyEntry
+    if (keyStore.containsAlias(keyAlias)) {
+        val entry = keyStore.getEntry(keyAlias, null) as KeyStore.PrivateKeyEntry
         return KeyPair(entry.certificate.publicKey, entry.privateKey)
     }
 
     val parameterSpec = KeyGenParameterSpec.Builder(
-        KEY_ALIAS,
+        keyAlias,
         KeyProperties.PURPOSE_SIGN,
     ).run {
         setDigests(KeyProperties.DIGEST_SHA256)
@@ -151,7 +154,7 @@ private fun storeCertificate(certificate: X509Certificate): Boolean {
         val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE).apply {
             load(null)
         }
-        keyStore.setCertificateEntry(CERT_ALIAS, certificate)
+        keyStore.setCertificateEntry(certAlias, certificate)
         true
     } catch (e: Exception) {
         // Log the exception for debugging
@@ -169,7 +172,7 @@ private fun getOrCreateCertificate(keyPair: KeyPair): X509Certificate {
     val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE).apply {
         load(null)
     }
-    return (keyStore.getCertificate(CERT_ALIAS) ?: createCertificate(keyPair)) as X509Certificate
+    return (keyStore.getCertificate(certAlias) ?: createCertificate(keyPair)) as X509Certificate
 }
 
 /**