use kotlinx-serialization with OATH Model

android/app/build.gradle

@@ -13,11 +13,13 @@ if (flutterRoot == null) {
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
 if (flutterVersionCode == null) {
+    //noinspection GroovyUnusedAssignment
     flutterVersionCode = '1'
 }
 
 def flutterVersionName = localProperties.getProperty('flutter.versionName')
 if (flutterVersionName == null) {
+    //noinspection GroovyUnusedAssignment
     flutterVersionName = '1.0'
 }
 
@@ -26,7 +28,7 @@ def authenticatorVersionName = "6.0.0-alpha.2"
 
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
-apply plugin: "org.jetbrains.kotlin.plugin.serialization"
+apply plugin: 'kotlinx-serialization'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
@@ -80,6 +82,7 @@ dependencies {
     api "com.yubico.yubikit:oath:$project.yubiKitVersion"
     api "com.yubico.yubikit:support:$project.yubiKitVersion"
 
+    implementation "org.jetbrains.kotlinx:kotlinx-serialization-core:1.0.0-RC"
     implementation 'org.jetbrains.kotlinx:kotlinx-serialization-json:1.3.2'
 
     // Lifecycle

android/app/proguard-rules.pro

@@ -5,4 +5,45 @@
 # For more details, see
 #   http://developer.android.com/guide/developing/tools/proguard.html
 
--dontwarn edu.umd.cs.findbugs.annotations.SuppressFBWarnings
+-dontwarn edu.umd.cs.findbugs.annotations.SuppressFBWarnings
+
+
+# Keep `Companion` object fields of serializable classes.
+# This avoids serializer lookup through `getDeclaredClasses` as done for named companion objects.
+-if @kotlinx.serialization.Serializable class **
+-keepclassmembers class <1> {
+    static <1>$Companion Companion;
+}
+
+# Keep `serializer()` on companion objects (both default and named) of serializable classes.
+-if @kotlinx.serialization.Serializable class ** {
+    static **$* *;
+}
+-keepclassmembers class <2>$<3> {
+    kotlinx.serialization.KSerializer serializer(...);
+}
+
+# Keep `INSTANCE.serializer()` of serializable objects.
+-if @kotlinx.serialization.Serializable class ** {
+    public static ** INSTANCE;
+}
+-keepclassmembers class <1> {
+    public static <1> INSTANCE;
+    kotlinx.serialization.KSerializer serializer(...);
+}
+
+# @Serializable and @Polymorphic are used at runtime for polymorphic serialization.
+-keepattributes RuntimeVisibleAnnotations,AnnotationDefault
+
+# Serializer for classes with named companion objects are retrieved using `getDeclaredClasses`.
+# If you have any, uncomment and replace classes with those containing named companion objects.
+#-keepattributes InnerClasses # Needed for `getDeclaredClasses`.
+#-if @kotlinx.serialization.Serializable class
+#com.example.myapplication.HasNamedCompanion, # <-- List serializable classes with named companions.
+#com.example.myapplication.HasNamedCompanion2
+#{
+#    static **$* *;
+#}
+#-keepnames class <1>$$serializer { # -keepnames suffices; class is kept when serializer() is kept.
+#    static <1>$$serializer INSTANCE;
+#}

android/app/src/main/kotlin/com/yubico/authenticator/oath/Conversion.kt

@@ -2,19 +2,7 @@ package com.yubico.authenticator.oath
 
 import com.yubico.yubikit.oath.Code
 import com.yubico.yubikit.oath.Credential
-import com.yubico.yubikit.oath.OathSession
 import com.yubico.yubikit.oath.OathType
-import kotlinx.serialization.json.JsonObject
-import kotlinx.serialization.json.JsonPrimitive
-
-fun OathSession.toJson(remembered: Boolean) = JsonObject(
-    mapOf(
-        "deviceId" to JsonPrimitive(deviceId),
-        "hasKey" to JsonPrimitive(isAccessKeySet),
-        "remembered" to JsonPrimitive(remembered),
-        "locked" to JsonPrimitive(isLocked)
-    )
-)
 
 fun ByteArray.asString() = joinToString(
     separator = ""
@@ -36,8 +24,8 @@ fun Credential.model(deviceId: String) = Model.Credential(
 
 fun Code.model() = Model.Code(
     value,
-    validFrom,
+    validFrom / 1000,
-    validUntil
+    validUntil / 1000
 )
 
 fun Map<Credential, Code?>.model(deviceId: String): Map<Model.Credential, Model.Code?> =

android/app/src/main/kotlin/com/yubico/authenticator/oath/Model.kt

@@ -1,23 +1,48 @@
 package com.yubico.authenticator.oath
 
-import kotlinx.serialization.json.JsonArray
+import kotlinx.serialization.KSerializer
-import kotlinx.serialization.json.JsonNull
+import kotlinx.serialization.SerialName
-import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.Serializable
-import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
 
 class Model {
 
+    @Serializable
+    data class Session(
+        @SerialName("device_id")
+        val deviceId: String = "",
+        @SerialName("has_key")
+        val isAccessKeySet: Boolean = false,
+        @SerialName("remembered")
+        val isRemembered: Boolean = false,
+        @SerialName("locked")
+        val isLocked: Boolean = false,
+        @SerialName("keystore")
+        val keystoreState: String = "unknown"
+    )
+
+    @Serializable(with = OathTypeSerializer::class)
     enum class OathType(val value: Byte) {
-        TOTP(0x20), HOTP(0x10)
+        TOTP(0x20),
+        HOTP(0x10);
     }
 
+    @Serializable
     data class Credential(
+        @SerialName("device_id")
         val deviceId: String,
         val id: String,
+        @SerialName("oath_type")
         val oathType: OathType,
         val period: Int,
         val issuer: String? = null,
+        @SerialName("name")
         val accountName: String,
+        @SerialName("touch_required")
         val touchRequired: Boolean
     ) {
         override fun equals(other: Any?): Boolean =
@@ -30,82 +55,62 @@ class Model {
         }
     }
 
-    data class Code(
+    @Serializable
+    class Code(
         val value: String? = null,
+        @SerialName("valid_from")
         val validFrom: Long,
-        val validUntil: Long
+        @SerialName("valid_to")
+        val validTo: Long
     )
 
+    @Serializable
     data class CredentialWithCode(
         val credential: Credential,
         val code: Code?
     )
 
+    object OathTypeSerializer : KSerializer<OathType> {
+        override fun deserialize(decoder: Decoder): OathType =
+            when (decoder.decodeByte()) {
+                OathType.HOTP.value -> OathType.HOTP
+                else -> OathType.TOTP
+            }
+
+        override val descriptor: SerialDescriptor =
+            PrimitiveSerialDescriptor("OathType", PrimitiveKind.BYTE)
+
+        override fun serialize(encoder: Encoder, value: OathType) {
+            encoder.encodeByte(value = value.value)
+        }
+
+    }
+
     companion object {
 
         fun Credential.isInteractive(): Boolean {
             return oathType == OathType.HOTP || (oathType == OathType.TOTP && touchRequired)
         }
 
-        fun Code.toJson() = JsonObject(
-            mapOf(
-                "value" to JsonPrimitive(value),
-                "valid_from" to JsonPrimitive(validFrom / 1000),
-                "valid_to" to JsonPrimitive(validUntil / 1000)
-            )
-        )
-
-        fun Credential.toJson() = JsonObject(
-            mapOf(
-                "id" to JsonPrimitive(id),
-                "device_id" to JsonPrimitive(deviceId),
-                "issuer" to JsonPrimitive(issuer),
-                "name" to JsonPrimitive(accountName),
-                "oath_type" to JsonPrimitive(oathType.value),
-                "period" to JsonPrimitive(period),
-                "touch_required" to JsonPrimitive(touchRequired),
-            )
-        )
-
-        fun Pair<Credential, Code?>.toJson() = JsonObject(
-            mapOf(
-                "credential" to first.toJson(),
-                "code" to (second?.toJson() ?: JsonNull)
-            )
-        )
-
-        fun CredentialWithCode.toJson() = JsonObject(
-            mapOf(
-                "credential" to credential.toJson(),
-                "code" to (code?.toJson() ?: JsonNull)
-            )
-        )
-
-        fun Map<Credential, Code?>.toJson() = JsonObject(
-            mapOf(
-                "entries" to JsonArray(
-                    map { it.toPair().toJson() }
-                )
-            )
-        )
     }
 
-    var deviceId: String = ""; private set
+    //var deviceId: String = ""; private set
+    var session = Session()
     var credentials = mutableMapOf<Credential, Code?>(); private set
 
     // resets the model to initial values
     // used when a usb key has been disconnected
     fun reset() {
         this.credentials.clear()
-        this.deviceId = ""
+        this.session = Session()
     }
 
     fun update(deviceId: String, credentials: Map<Credential, Code?>) {
-        if (this.deviceId != deviceId) {
+        if (this.session.deviceId != deviceId) {
             // device was changed, we use the new list
             this.credentials.clear()
             this.credentials.putAll(from = credentials)
-            this.deviceId = deviceId
+            this.session = Session(deviceId)
         } else {
 
             // update codes for non interactive keys
@@ -126,7 +131,7 @@ class Model {
     }
 
     fun add(deviceId: String, credential: Credential, code: Code?): CredentialWithCode? {
-        if (this.deviceId != deviceId) {
+        if (this.session.deviceId != deviceId) {
             return null
         }
 
@@ -140,7 +145,7 @@ class Model {
         oldCredential: Credential,
         newCredential: Credential
     ): Credential? {
-        if (this.deviceId != deviceId) {
+        if (this.session.deviceId != deviceId) {
             return null
         }
 
@@ -162,7 +167,7 @@ class Model {
     }
 
     fun updateCode(deviceId: String, credential: Credential, code: Code?): Code? {
-        if (this.deviceId != deviceId) {
+        if (this.session.deviceId != deviceId) {
             return null
         }
 

android/app/src/main/kotlin/com/yubico/authenticator/oath/OathManager.kt

@@ -7,7 +7,6 @@ import androidx.lifecycle.Observer
 import com.yubico.authenticator.*
 import com.yubico.authenticator.api.Pigeon.*
 import com.yubico.authenticator.data.device.toJson
-import com.yubico.authenticator.oath.Model.Companion.toJson
 import com.yubico.authenticator.oath.keystore.ClearingMemProvider
 import com.yubico.authenticator.oath.keystore.KeyStoreProvider
 import com.yubico.yubikit.android.transport.nfc.NfcYubiKeyDevice
@@ -19,6 +18,8 @@ import com.yubico.yubikit.oath.*
 import com.yubico.yubikit.support.DeviceUtil
 import io.flutter.plugin.common.BinaryMessenger
 import kotlinx.coroutines.*
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import java.net.URI
 import java.util.concurrent.Executors
 import kotlin.coroutines.resume
@@ -33,6 +34,12 @@ class OathManager(
     private val dialogManager: DialogManager
 ) : OathApi {
 
+    // application specific Json settings
+    private val json = Json {
+        allowStructuredMapKeys = true
+        encodeDefaults = true
+    }
+
     private val _dispatcher = Executors.newSingleThreadExecutor().asCoroutineDispatcher()
     private val coroutineScope = CoroutineScope(SupervisorJob() + _dispatcher)
 
@@ -152,7 +159,7 @@ class OathManager(
                     }
                     if (response.isUnlocked == true) {
                         _model.update(it.deviceId, calculateOathCodes(it).model(it.deviceId))
-                        codes = _model.credentials.toJson().toString()
+                        codes = json.encodeToString(_model.credentials)
                     }
                     returnSuccess(result, response)
                 }
@@ -253,7 +260,7 @@ class OathManager(
                         )
 
                         if (addedCred != null) {
-                            val jsonResult = addedCred.toJson().toString()
+                            val jsonResult = json.encodeToString(addedCred)
                             returnSuccess(result, jsonResult)
                         } else {
                             // TODO - figure out better error handling here
@@ -281,7 +288,8 @@ class OathManager(
                         )
 
                         if (renamedCredential != null) {
-                            val jsonResult = renamedCredential.toJson().toString()
+                            val jsonResult =
+                                json.encodeToString(renamedCredential)
 
                             returnSuccess(result, jsonResult)
                         } else {
@@ -322,7 +330,7 @@ class OathManager(
                             session.deviceId,
                             calculateOathCodes(session).model(session.deviceId)
                         )
-                        val resultJson = _model.credentials.toJson().toString()
+                        val resultJson = json.encodeToString(_model.credentials)
                         returnSuccess(result, resultJson)
                     }
                 }
@@ -347,7 +355,7 @@ class OathManager(
                         )
 
                         if (code != null) {
-                            val resultJson = code.toJson().toString()
+                            val resultJson = json.encodeToString(code)
 
                             returnSuccess(result, resultJson)
                         } else {
@@ -426,9 +434,14 @@ class OathManager(
                 tryToUnlockOathSession(oathSession)
                 val isRemembered = _keyManager.isRemembered(oathSession.deviceId)
 
-                val oathSessionData = oathSession
+                _model.session = Model.Session(
-                    .toJson(isRemembered)
+                    oathSession.deviceId,
-                    .toString()
+                    oathSession.isAccessKeySet,
+                    isRemembered,
+                    oathSession.isLocked
+                )
+
+                val oathSessionData = json.encodeToString(_model.session)
                 it.resume(oathSessionData)
             }
         }
@@ -445,7 +458,7 @@ class OathManager(
                         session.deviceId,
                         calculateOathCodes(session).model(session.deviceId)
                     )
-                    val resultJson = _model.credentials.toJson().toString()
+                    val resultJson = json.encodeToString(_model.credentials)
                     it.resume(resultJson)
                 }
             }

android/build.gradle

@@ -1,5 +1,5 @@
 buildscript {
-    ext.kotlin_version = '1.6.10'
+    ext.kotlin_version = '1.6.20'
     repositories {
         google()
         mavenCentral()
@@ -8,7 +8,7 @@ buildscript {
     dependencies {
         classpath 'com.android.tools.build:gradle:7.1.3'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        classpath "org.jetbrains.kotlin:kotlin-serialization:1.6.10"
+        classpath "org.jetbrains.kotlin:kotlin-serialization:$kotlin_version"
     }
 }
 

lib/android/oath/command_providers.dart

@@ -14,11 +14,7 @@ class _StateProvider extends StateNotifier<OathState?> {
 
   void setFromString(String input) {
     var resultJson = jsonDecode(input);
-    state = OathState(resultJson['deviceId'],
+    state = OathState.fromJson(resultJson);
-        hasKey: resultJson['hasKey'],
-        remembered: resultJson['remembered'],
-        locked: resultJson['locked'],
-        keystore: KeystoreState.unknown);
   }
 }
 
@@ -33,11 +29,21 @@ class _CredentialsProvider extends StateNotifier<List<OathPair>?> {
   void setFromString(String input) {
     var result = jsonDecode(input);
 
+    /// structure of data in the json object is:
+    /// [credential1, code1, credential2, code2, ...]
+
     final List<OathPair> pairs = [];
-    for (var e in result['entries']) {
+    if (result is List<dynamic>) {
-      final credential = OathCredential.fromJson(e['credential']);
+      for (var index = 0; index < result.length / 2; index++) {
-      final code = e['code'] == null ? null : OathCode.fromJson(e['code']);
+        final credential = result[index * 2];
-      pairs.add(OathPair(credential, code));
+        final code = result[index * 2 + 1];
+        pairs.add(
+          OathPair(
+            OathCredential.fromJson(credential),
+            code == null ? null : OathCode.fromJson(code),
+          ),
+        );
+      }
     }
 
     state = pairs;