feat(classic): MIFARE Classic key recovery via PN533 nested attack

app-keymanager/build.gradle.kts

@@ -0,0 +1,41 @@
+plugins {
+    alias(libs.plugins.kotlin.multiplatform)
+    alias(libs.plugins.android.kotlin.multiplatform.library)
+    alias(libs.plugins.kotlin.serialization)
+    alias(libs.plugins.compose.multiplatform)
+    alias(libs.plugins.kotlin.compose)
+}
+
+kotlin {
+    androidLibrary {
+        namespace = "com.codebutler.farebot.app.keymanager"
+        compileSdk =
+            libs.versions.compileSdk
+                .get()
+                .toInt()
+        minSdk =
+            libs.versions.minSdk
+                .get()
+                .toInt()
+    }
+
+    // NO iOS targets
+
+    sourceSets {
+        commonMain.dependencies {
+            implementation(libs.compose.resources)
+            implementation(libs.compose.runtime)
+            implementation(compose.foundation)
+            implementation(compose.material3)
+            implementation(compose.materialIconsExtended)
+            implementation(libs.navigation.compose)
+            implementation(libs.lifecycle.viewmodel.compose)
+            implementation(libs.kotlinx.coroutines.core)
+            implementation(libs.kotlinx.serialization.json)
+            implementation(project(":base"))
+            implementation(project(":card"))
+            implementation(project(":card:classic"))
+            implementation(project(":keymanager"))
+        }
+    }
+}

app-keymanager/src/commonMain/composeResources/values/strings.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="add_key">Add Key</string>
+    <string name="back">Back</string>
+    <string name="cancel">Cancel</string>
+    <string name="card_id">Card ID</string>
+    <string name="card_type">Card Type</string>
+    <string name="delete">Delete</string>
+    <string name="delete_selected_keys">Delete %1$d selected keys?</string>
+    <string name="enter_manually">Enter manually</string>
+    <string name="hold_nfc_card">Hold your NFC card against the device to detect its ID and type.</string>
+    <string name="import_file_button">Import File</string>
+    <string name="key_data">Key Data</string>
+    <string name="keys">Keys</string>
+    <string name="keys_loaded">Keys are built in.</string>
+    <string name="keys_required">Encryption keys are required to read this card.</string>
+    <string name="locked_card">Locked Card</string>
+    <string name="n_selected">%1$d selected</string>
+    <string name="nfc">NFC</string>
+    <string name="no_keys">No keys added yet.</string>
+    <string name="select_all">Select all</string>
+    <string name="tap_your_card">Tap your card</string>
+</resources>

app-keymanager/src/commonMain/kotlin/com/codebutler/farebot/app/keymanager/KeyManagerPluginImpl.kt

@@ -0,0 +1,202 @@
+/*
+ * KeyManagerPluginImpl.kt
+ *
+ * This file is part of FareBot.
+ * Learn more at: https://codebutler.github.io/farebot/
+ *
+ * Copyright (C) 2026 Eric Butler <eric@codebutler.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.codebutler.farebot.app.keymanager
+
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.navigation.NavGraphBuilder
+import androidx.navigation.NavHostController
+import androidx.navigation.NavType
+import androidx.navigation.compose.composable
+import androidx.navigation.navArgument
+import androidx.savedstate.read
+import com.codebutler.farebot.app.keymanager.ui.AddKeyScreen
+import com.codebutler.farebot.app.keymanager.ui.KeysScreen
+import com.codebutler.farebot.app.keymanager.viewmodel.AddKeyViewModel
+import com.codebutler.farebot.app.keymanager.viewmodel.KeysViewModel
+import com.codebutler.farebot.card.CardType
+import com.codebutler.farebot.card.classic.ClassicKeyRecovery
+import com.codebutler.farebot.card.classic.key.ClassicCardKeys
+import com.codebutler.farebot.keymanager.NestedAttackKeyRecovery
+import com.codebutler.farebot.persist.CardKeysPersister
+import com.codebutler.farebot.shared.nfc.CardScanner
+import farebot.app_keymanager.generated.resources.Res
+import farebot.app_keymanager.generated.resources.add_key
+import farebot.app_keymanager.generated.resources.keys
+import farebot.app_keymanager.generated.resources.keys_loaded
+import farebot.app_keymanager.generated.resources.keys_required
+import farebot.app_keymanager.generated.resources.locked_card
+import kotlinx.serialization.json.Json
+import org.jetbrains.compose.resources.StringResource
+
+/**
+ * Provides all key management functionality.
+ *
+ * This class does NOT implement [com.codebutler.farebot.shared.plugin.KeyManagerPlugin]
+ * directly to avoid a circular dependency (`:app-keymanager` cannot depend on `:app`).
+ * Platform AppGraphs wrap this as a [KeyManagerPlugin] adapter.
+ */
+class KeyManagerPluginImpl(
+    private val cardKeysPersister: CardKeysPersister,
+    private val json: Json,
+) {
+    val classicKeyRecovery: ClassicKeyRecovery = NestedAttackKeyRecovery()
+
+    fun navigateToKeys(navController: NavHostController) {
+        navController.navigate(KEYS_ROUTE)
+    }
+
+    fun navigateToAddKey(
+        navController: NavHostController,
+        tagId: String? = null,
+        cardType: CardType? = null,
+    ) {
+        navController.navigate(buildAddKeyRoute(tagId, cardType))
+    }
+
+    fun NavGraphBuilder.registerKeyRoutes(
+        navController: NavHostController,
+        cardKeysPersister: CardKeysPersister,
+        cardScanner: CardScanner?,
+        onPickFile: ((ByteArray?) -> Unit) -> Unit,
+    ) {
+        composable(KEYS_ROUTE) {
+            val keysViewModel = viewModel { KeysViewModel(cardKeysPersister) }
+            val uiState by keysViewModel.uiState.collectAsState()
+
+            LaunchedEffect(Unit) {
+                keysViewModel.loadKeys()
+            }
+
+            KeysScreen(
+                uiState = uiState,
+                onBack = { navController.popBackStack() },
+                onNavigateToAddKey = { navController.navigate(buildAddKeyRoute()) },
+                onDeleteKey = { keyId -> keysViewModel.deleteKey(keyId) },
+                onToggleSelection = { keyId -> keysViewModel.toggleSelection(keyId) },
+                onClearSelection = { keysViewModel.clearSelection() },
+                onSelectAll = { keysViewModel.selectAll() },
+                onDeleteSelected = { keysViewModel.deleteSelected() },
+            )
+        }
+
+        composable(
+            route = ADD_KEY_ROUTE,
+            arguments =
+                listOf(
+                    navArgument("tagId") {
+                        type = NavType.StringType
+                        nullable = true
+                        defaultValue = null
+                    },
+                    navArgument("cardType") {
+                        type = NavType.StringType
+                        nullable = true
+                        defaultValue = null
+                    },
+                ),
+        ) { backStackEntry ->
+            val addKeyViewModel = viewModel { AddKeyViewModel(cardKeysPersister, cardScanner) }
+            val uiState by addKeyViewModel.uiState.collectAsState()
+
+            val prefillTagId = backStackEntry.arguments?.read { getStringOrNull("tagId") }
+            val prefillCardTypeName = backStackEntry.arguments?.read { getStringOrNull("cardType") }
+
+            LaunchedEffect(prefillTagId, prefillCardTypeName) {
+                if (prefillTagId != null && prefillCardTypeName != null) {
+                    val ct = CardType.entries.firstOrNull { it.name == prefillCardTypeName }
+                    if (ct != null) {
+                        addKeyViewModel.prefillCardData(prefillTagId, ct)
+                    }
+                }
+            }
+
+            LaunchedEffect(Unit) {
+                addKeyViewModel.startObservingTags()
+            }
+
+            LaunchedEffect(Unit) {
+                addKeyViewModel.keySaved.collect {
+                    navController.popBackStack()
+                }
+            }
+
+            AddKeyScreen(
+                uiState = uiState,
+                onBack = { navController.popBackStack() },
+                onSaveKey = { cardId, ct, keyData ->
+                    addKeyViewModel.saveKey(cardId, ct, keyData)
+                },
+                onEnterManually = { addKeyViewModel.enterManualMode() },
+                onImportFile = {
+                    onPickFile { bytes ->
+                        if (bytes != null) {
+                            addKeyViewModel.importKeyFile(bytes)
+                        }
+                    }
+                },
+            )
+        }
+    }
+
+    fun getCardKeysForTag(tagId: String): ClassicCardKeys? {
+        val savedKey = cardKeysPersister.getForTagId(tagId) ?: return null
+        return when (savedKey.cardType) {
+            CardType.MifareClassic -> json.decodeFromString(ClassicCardKeys.serializer(), savedKey.keyData)
+            else -> null
+        }
+    }
+
+    fun getGlobalKeys(): List<ByteArray> =
+        try {
+            cardKeysPersister.getGlobalKeys()
+        } catch (e: Exception) {
+            println("[KeyManager] Failed to load global keys: ${e.message}")
+            emptyList()
+        }
+
+    val lockedCardTitle: StringResource get() = Res.string.locked_card
+    val keysRequiredMessage: StringResource get() = Res.string.keys_required
+    val addKeyLabel: StringResource get() = Res.string.add_key
+    val keysLabel: StringResource get() = Res.string.keys
+    val keysLoadedLabel: StringResource get() = Res.string.keys_loaded
+
+    companion object {
+        private const val KEYS_ROUTE = "keys"
+        private const val ADD_KEY_ROUTE = "add_key?tagId={tagId}&cardType={cardType}"
+
+        private fun buildAddKeyRoute(
+            tagId: String? = null,
+            cardType: CardType? = null,
+        ): String =
+            buildString {
+                append("add_key")
+                val params = mutableListOf<String>()
+                if (tagId != null) params.add("tagId=$tagId")
+                if (cardType != null) params.add("cardType=${cardType.name}")
+                if (params.isNotEmpty()) append("?${params.joinToString("&")}")
+            }
+    }
+}

app/src/commonMain/kotlin/com/codebutler/farebot/shared/ui/screen/AddKeyScreen.kt → app-keymanager/src/commonMain/kotlin/com/codebutler/farebot/app/keymanager/ui/AddKeyScreen.kt

@@ -1,4 +1,4 @@
-package com.codebutler.farebot.shared.ui.screen
+package com.codebutler.farebot.app.keymanager.ui
 
 import androidx.compose.animation.Crossfade
 import androidx.compose.foundation.layout.Arrangement
@@ -35,18 +35,17 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import com.codebutler.farebot.card.CardType
-import com.codebutler.farebot.shared.ui.layout.ContentWidthConstraint
-import farebot.app.generated.resources.Res
-import farebot.app.generated.resources.add_key
-import farebot.app.generated.resources.back
-import farebot.app.generated.resources.card_id
-import farebot.app.generated.resources.card_type
-import farebot.app.generated.resources.enter_manually
-import farebot.app.generated.resources.hold_nfc_card
-import farebot.app.generated.resources.import_file_button
-import farebot.app.generated.resources.key_data
-import farebot.app.generated.resources.nfc
-import farebot.app.generated.resources.tap_your_card
+import farebot.app_keymanager.generated.resources.Res
+import farebot.app_keymanager.generated.resources.add_key
+import farebot.app_keymanager.generated.resources.back
+import farebot.app_keymanager.generated.resources.card_id
+import farebot.app_keymanager.generated.resources.card_type
+import farebot.app_keymanager.generated.resources.enter_manually
+import farebot.app_keymanager.generated.resources.hold_nfc_card
+import farebot.app_keymanager.generated.resources.import_file_button
+import farebot.app_keymanager.generated.resources.key_data
+import farebot.app_keymanager.generated.resources.nfc
+import farebot.app_keymanager.generated.resources.tap_your_card
 import org.jetbrains.compose.resources.stringResource
 
 data class AddKeyUiState(

app-keymanager/src/commonMain/kotlin/com/codebutler/farebot/app/keymanager/ui/ContentWidthConstraint.kt

@@ -0,0 +1,25 @@
+package com.codebutler.farebot.app.keymanager.ui
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.widthIn
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+
+@Composable
+fun ContentWidthConstraint(
+    maxWidth: Dp = 640.dp,
+    content: @Composable () -> Unit,
+) {
+    Box(
+        modifier = Modifier.fillMaxWidth(),
+        contentAlignment = Alignment.TopCenter,
+    ) {
+        Box(modifier = Modifier.widthIn(max = maxWidth).fillMaxWidth()) {
+            content()
+        }
+    }
+}

app/src/commonMain/kotlin/com/codebutler/farebot/shared/ui/screen/KeysScreen.kt → app-keymanager/src/commonMain/kotlin/com/codebutler/farebot/app/keymanager/ui/KeysScreen.kt

@@ -1,4 +1,4 @@
-package com.codebutler.farebot.shared.ui.screen
+package com.codebutler.farebot.app.keymanager.ui
 
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.combinedClickable
@@ -39,17 +39,16 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
-import com.codebutler.farebot.shared.ui.layout.ContentWidthConstraint
-import farebot.app.generated.resources.Res
-import farebot.app.generated.resources.add_key
-import farebot.app.generated.resources.back
-import farebot.app.generated.resources.cancel
-import farebot.app.generated.resources.delete
-import farebot.app.generated.resources.delete_selected_keys
-import farebot.app.generated.resources.keys
-import farebot.app.generated.resources.n_selected
-import farebot.app.generated.resources.no_keys
-import farebot.app.generated.resources.select_all
+import farebot.app_keymanager.generated.resources.Res
+import farebot.app_keymanager.generated.resources.add_key
+import farebot.app_keymanager.generated.resources.back
+import farebot.app_keymanager.generated.resources.cancel
+import farebot.app_keymanager.generated.resources.delete
+import farebot.app_keymanager.generated.resources.delete_selected_keys
+import farebot.app_keymanager.generated.resources.keys
+import farebot.app_keymanager.generated.resources.n_selected
+import farebot.app_keymanager.generated.resources.no_keys
+import farebot.app_keymanager.generated.resources.select_all
 import org.jetbrains.compose.resources.stringResource
 
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalFoundationApi::class)

app/src/commonMain/kotlin/com/codebutler/farebot/shared/ui/screen/KeysUiState.kt → app-keymanager/src/commonMain/kotlin/com/codebutler/farebot/app/keymanager/ui/KeysUiState.kt

@@ -1,4 +1,4 @@
-package com.codebutler.farebot.shared.ui.screen
+package com.codebutler.farebot.app.keymanager.ui
 
 data class KeysUiState(
     val isLoading: Boolean = true,