feat: Add support for NIP-55 (#18)

Reviewed-on: #18

composeApp/src/androidMain/AndroidManifest.xml

@@ -11,6 +11,14 @@
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
 
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.VIEW" />
+            <category android:name="android.intent.category.BROWSABLE" />
+            <data android:scheme="nostrsigner" />
+        </intent>
+    </queries>
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"

composeApp/src/androidMain/kotlin/su/reya/coop/AndroidExternalSigner.kt

@@ -0,0 +1,147 @@
+package su.reya.coop
+
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import androidx.core.net.toUri
+import rust.nostr.sdk.PublicKey
+import rust.nostr.sdk.UnsignedEvent
+
+class AndroidExternalSigner(
+    private val context: Context,
+    private val launcher: ExternalSignerLauncher,
+) : ExternalSignerHandler {
+    private var cachedPackageName: String? = null
+
+    private data class ContentResolverResult(
+        val result: String,
+        val event: String? = null,
+    )
+
+    private fun queryContentResolver(
+        type: String,
+        payload: String,
+        pubkey: PublicKey? = null,
+        currentUser: PublicKey? = null,
+    ): ContentResolverResult? {
+        val uri = "content://$cachedPackageName.${type.uppercase()}".toUri()
+        val projection = mutableListOf<String?>().apply {
+            add(payload)
+            add(pubkey?.toHex() ?: "")
+            add(currentUser?.toHex() ?: "")
+        }
+
+        val cursor = context.contentResolver.query(
+            uri,
+            projection.toTypedArray(),
+            null, null, null,
+        ) ?: return null
+
+        return cursor.use {
+            if (it.getColumnIndex("rejected") > -1) return null
+            if (it.moveToFirst()) {
+                val resultIndex = it.getColumnIndex("result")
+                val result = if (resultIndex > -1) it.getString(resultIndex) else null
+
+                val eventIndex = it.getColumnIndex("event")
+                val event = if (eventIndex > -1) it.getString(eventIndex) else null
+
+                ContentResolverResult(result = result!!, event = event)
+            } else null
+        }
+    }
+
+    private suspend fun request(
+        type: String,
+        payload: String,
+        pubkey: PublicKey? = null,
+        currentUser: PublicKey? = null,
+        resultKey: String = "result",
+        extras: Map<String, String> = emptyMap(),
+    ): String? {
+        // Try Content Resolver first
+        queryContentResolver(type, payload, pubkey, currentUser)?.let {
+            return it.result
+        }
+
+        // Fall back to Intent
+        val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$payload".toUri()).apply {
+            `package` = cachedPackageName
+            putExtra("type", type)
+            if (pubkey != null) putExtra("pubkey", pubkey.toHex())
+            if (currentUser != null) putExtra("current_user", currentUser.toHex())
+            extras.forEach { (k, v) -> putExtra(k, v) }
+        }
+
+        val result = launcher.launch(intent)
+        if (result.resultCode != Activity.RESULT_OK) return null
+
+        val data = result.data ?: return null
+        if (data.getBooleanExtra("rejected", false)) return null
+
+        return data.getStringExtra(resultKey)
+    }
+
+    override fun isAvailable(): Boolean {
+        val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:".toUri())
+        return context.packageManager.queryIntentActivities(intent, 0).isNotEmpty()
+    }
+
+    override fun setPackageName(packageName: String) {
+        cachedPackageName = packageName
+    }
+
+    override suspend fun getPublicKey(permissions: String?): ExternalSignerResult? {
+        val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:".toUri()).apply {
+            putExtra("type", "get_public_key")
+            if (permissions != null) putExtra("permissions", permissions)
+        }
+
+        val result = launcher.launch(intent)
+        if (result.resultCode != Activity.RESULT_OK) return null
+
+        val data = result.data ?: return null
+        if (data.getBooleanExtra("rejected", false)) return null
+
+        val pubkey = data.getStringExtra("result") ?: return null
+        val packageName = data.getStringExtra("package") ?: return null
+        cachedPackageName = packageName
+
+        return ExternalSignerResult(PublicKey.parse(pubkey), packageName)
+    }
+
+    override suspend fun signEvent(event: UnsignedEvent, currentUser: PublicKey): String? {
+        val extras = event.id()?.let { mapOf("id" to it.toHex()) } ?: emptyMap()
+        return request(
+            type = "sign_event",
+            payload = event.asJson(),
+            currentUser = currentUser,
+            resultKey = "event",
+            extras = extras,
+        )
+    }
+
+    override suspend fun nip04Encrypt(plaintext: String, pubkey: PublicKey): String? {
+        return request("nip04_encrypt", plaintext, pubkey)
+    }
+
+    override suspend fun nip04Decrypt(ciphertext: String, pubkey: PublicKey): String? {
+        return request("nip04_decrypt", ciphertext, pubkey)
+    }
+
+    override suspend fun nip44Encrypt(
+        plaintext: String,
+        pubkey: PublicKey,
+        currentUser: PublicKey
+    ): String? {
+        return request("nip44_encrypt", plaintext, pubkey, currentUser)
+    }
+
+    override suspend fun nip44Decrypt(
+        ciphertext: String,
+        pubkey: PublicKey,
+        currentUser: PublicKey
+    ): String? {
+        return request("nip44_decrypt", ciphertext, pubkey, currentUser)
+    }
+}

composeApp/src/androidMain/kotlin/su/reya/coop/ExternalSignerLauncher.kt

@@ -0,0 +1,28 @@
+package su.reya.coop
+
+import android.content.Intent
+import androidx.activity.result.ActivityResult
+import androidx.activity.result.ActivityResultLauncher
+import kotlinx.coroutines.CompletableDeferred
+
+class ExternalSignerLauncher {
+    private var launcher: ActivityResultLauncher<Intent>? = null
+    private var pendingResult: CompletableDeferred<ActivityResult>? = null
+
+    fun register(launcher: ActivityResultLauncher<Intent>) {
+        this.launcher = launcher
+    }
+
+    suspend fun launch(intent: Intent): ActivityResult {
+        val deferred = CompletableDeferred<ActivityResult>()
+        pendingResult = deferred
+        launcher?.launch(intent)
+            ?: throw IllegalStateException("ExternalSignerLauncher not registered")
+        return deferred.await()
+    }
+
+    fun onResult(result: ActivityResult) {
+        pendingResult?.complete(result)
+        pendingResult = null
+    }
+}

composeApp/src/androidMain/kotlin/su/reya/coop/MainActivity.kt

@@ -2,9 +2,12 @@ package su.reya.coop
 
 import android.content.Intent
 import android.os.Bundle
+import android.os.Process
+import android.util.Log
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.activity.viewModels
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
 import androidx.lifecycle.ProcessLifecycleOwner
@@ -14,11 +17,16 @@ import su.reya.coop.coop.storage.SecretStore
 import kotlin.system.exitProcess
 
 class MainActivity : ComponentActivity() {
+    companion object {
+        val externalSignerLauncher = ExternalSignerLauncher()
+    }
+
     private val viewModel: NostrViewModel by viewModels {
         object : ViewModelProvider.Factory {
             override fun <T : ViewModel> create(modelClass: Class<T>): T {
                 val secretStore = SecretStore(this@MainActivity)
-                return NostrViewModel(NostrManager.instance, secretStore) as T
+                val androidSigner = AndroidExternalSigner(this@MainActivity, externalSignerLauncher)
+                return NostrViewModel(NostrManager.instance, secretStore, androidSigner) as T
             }
         }
     }
@@ -26,10 +34,9 @@ class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         Thread.setDefaultUncaughtExceptionHandler { thread, throwable ->
             throwable.printStackTrace()
-            android.util.Log.e(
+
-                "CoopCrash",
+            Log.e(
-                "Uncaught exception in thread ${thread.name}",
+                "CoopCrash", "Uncaught exception in thread ${thread.name}", throwable
-                throwable
             )
 
             // Start the Crash Activity
@@ -40,10 +47,17 @@ class MainActivity : ComponentActivity() {
             startActivity(intent)
 
             // Exit
-            android.os.Process.killProcess(android.os.Process.myPid())
+            Process.killProcess(Process.myPid())
             exitProcess(1)
         }
 
+        val resultLauncher = registerForActivityResult(
+            ActivityResultContracts.StartActivityForResult()
+        ) { result ->
+            externalSignerLauncher.onResult(result)
+        }
+        externalSignerLauncher.register(resultLauncher)
+
         val splashScreen = installSplashScreen()
         enableEdgeToEdge()
 

composeApp/src/androidMain/kotlin/su/reya/coop/screens/ImportScreen.kt

@@ -78,7 +78,7 @@ fun ImportScreen() {
 
     val scope = rememberCoroutineScope()
 
-    val isLoggedIn by viewModel.isLoggedIn.collectAsStateWithLifecycle(false)
+    val isBusy by viewModel.isBusy.collectAsStateWithLifecycle(false)
     var secret by remember { mutableStateOf("") }
     var pubkey by remember { mutableStateOf<PublicKey?>(null) }
 
@@ -205,7 +205,7 @@ fun ImportScreen() {
                             BasicTextField(
                                 value = secret,
                                 onValueChange = { secret = it },
-                                enabled = !isLoggedIn,
+                                enabled = !isBusy,
                                 modifier = Modifier.fillMaxWidth(),
                                 maxLines = 4,
                                 keyboardOptions = KeyboardOptions(
@@ -258,9 +258,9 @@ fun ImportScreen() {
                             modifier = Modifier
                                 .fillMaxWidth()
                                 .height(ButtonDefaults.MediumContainerHeight),
-                            enabled = secret.isNotBlank() && !isLoggedIn,
+                            enabled = secret.isNotBlank() && !isBusy,
                         ) {
-                            if (isLoggedIn) {
+                            if (isBusy) {
                                 LoadingIndicator()
                             } else {
                                 Text(

composeApp/src/androidMain/kotlin/su/reya/coop/screens/NewIdentityScreen.kt

@@ -15,12 +15,12 @@ fun NewIdentityScreen() {
     val viewModel = LocalNostrViewModel.current
     val navigator = LocalNavigator.current
     val scope = rememberCoroutineScope()
-    val isLoggedIn by viewModel.isLoggedIn.collectAsStateWithLifecycle(false)
+    val isBusy by viewModel.isBusy.collectAsStateWithLifecycle(false)
 
     ProfileEditor(
         title = "Create a new identity",
         buttonLabel = "Continue",
-        isBusy = isLoggedIn,
+        isBusy = isBusy,
         onBack = { navigator.goBack() },
         onConfirm = { name, bio, bytes, type ->
             scope.launch {

composeApp/src/androidMain/kotlin/su/reya/coop/screens/OnboardingScreen.kt

@@ -1,5 +1,6 @@
 package su.reya.coop.screens
 
+import android.content.Intent
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -13,13 +14,17 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.Button
 import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.material3.FilledTonalButton
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Scaffold
+import androidx.compose.material3.SnackbarDuration
 import androidx.compose.material3.SnackbarHost
+import androidx.compose.material3.SnackbarResult
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Size
@@ -27,6 +32,7 @@ import androidx.compose.ui.graphics.ColorFilter
 import androidx.compose.ui.graphics.drawscope.rotate
 import androidx.compose.ui.graphics.drawscope.translate
 import androidx.compose.ui.graphics.painter.Painter
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.LinkAnnotation
 import androidx.compose.ui.text.SpanStyle
 import androidx.compose.ui.text.TextLinkStyles
@@ -34,10 +40,13 @@ import androidx.compose.ui.text.buildAnnotatedString
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
+import androidx.core.net.toUri
 import coop.composeapp.generated.resources.Res
 import coop.composeapp.generated.resources.coop
+import kotlinx.coroutines.launch
 import org.jetbrains.compose.resources.painterResource
 import su.reya.coop.LocalNavigator
+import su.reya.coop.LocalNostrViewModel
 import su.reya.coop.LocalSnackbarHostState
 import su.reya.coop.Screen
 import su.reya.coop.shared.getExpressiveFontFamily
@@ -45,11 +54,15 @@ import su.reya.coop.shared.getExpressiveFontFamily
 @OptIn(ExperimentalMaterial3ExpressiveApi::class)
 @Composable
 fun OnboardingScreen() {
+    val context = LocalContext.current
     val snackbarHostState = LocalSnackbarHostState.current
     val navigator = LocalNavigator.current
+    val viewModel = LocalNostrViewModel.current
+    val scope = rememberCoroutineScope()
 
     val logoPainter = painterResource(Res.drawable.coop)
     val expressiveFont = getExpressiveFontFamily()
+    
     val annotatedText = buildAnnotatedString {
         append("By using Coop, you agree to accept\nour ")
         // Push "Terms of Use" link
@@ -142,7 +155,44 @@ fun OnboardingScreen() {
                                 )
                             }
                             Spacer(modifier = Modifier.size(8.dp))
-                            OutlinedButton(
+                            FilledTonalButton(
+                                onClick = {
+                                    scope.launch {
+                                        if (viewModel.isExternalSignerAvailable()) {
+                                            try {
+                                                viewModel.connectExternalSigner()
+                                                navigator.navigate(Screen.Home)
+                                            } catch (e: Exception) {
+                                                e.message?.let { snackbarHostState.showSnackbar(it) }
+                                            }
+                                        } else {
+                                            val result = snackbarHostState.showSnackbar(
+                                                message = "External signer not installed. Please install Amber or alternatives.",
+                                                actionLabel = "Install",
+                                                withDismissAction = true,
+                                                duration = SnackbarDuration.Long
+                                            )
+                                            if (result == SnackbarResult.ActionPerformed) {
+                                                val intent = Intent(
+                                                    Intent.ACTION_VIEW,
+                                                    "https://zapstore.dev/apps/com.greenart7c3.nostrsigner".toUri()
+                                                )
+                                                context.startActivity(intent)
+                                            }
+                                        }
+                                    }
+                                },
+                                modifier = Modifier
+                                    .fillMaxWidth()
+                                    .height(ButtonDefaults.MediumContainerHeight),
+                            ) {
+                                Text(
+                                    text = "Connect with Amber",
+                                    style = MaterialTheme.typography.titleMedium,
+                                )
+                            }
+                            Spacer(modifier = Modifier.size(8.dp))
+                            TextButton(
                                 onClick = { navigator.navigate(Screen.Import) },
                                 modifier = Modifier
                                     .fillMaxWidth()

composeApp/src/androidMain/kotlin/su/reya/coop/screens/UpdateProfileScreen.kt

@@ -18,7 +18,7 @@ fun UpdateProfileScreen() {
 
     val currentUser = viewModel.currentUser() ?: return
     val metadata by viewModel.getMetadata(currentUser).collectAsState(initial = null)
-    val isBusy by viewModel.isLoggedIn.collectAsStateWithLifecycle(false)
+    val isBusy by viewModel.isBusy.collectAsStateWithLifecycle(false)
 
     val profile = metadata?.asRecord()
 

shared/src/commonMain/kotlin/su/reya/coop/ExternalSignerHandler.kt

@@ -0,0 +1,44 @@
+package su.reya.coop
+
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+import rust.nostr.sdk.PublicKey
+import rust.nostr.sdk.UnsignedEvent
+
+/**
+ * Platform interface for NIP-55 external signer communication.
+ * Implemented on Android; no-op/null on other platforms.
+ */
+interface ExternalSignerHandler {
+    fun isAvailable(): Boolean
+    fun setPackageName(packageName: String)
+    suspend fun getPublicKey(permissions: String? = null): ExternalSignerResult?
+    suspend fun signEvent(event: UnsignedEvent, currentUser: PublicKey): String?
+    suspend fun nip04Encrypt(plaintext: String, pubkey: PublicKey): String?
+    suspend fun nip04Decrypt(ciphertext: String, pubkey: PublicKey): String?
+    suspend fun nip44Encrypt(plaintext: String, pubkey: PublicKey, currentUser: PublicKey): String?
+    suspend fun nip44Decrypt(ciphertext: String, pubkey: PublicKey, currentUser: PublicKey): String?
+}
+
+@Serializable
+data class SignerPermission(
+    val type: String,
+    val kind: Int? = null,
+)
+
+object SignerPermissions {
+    fun signEvent(kind: Int? = null) = SignerPermission(type = "sign_event", kind = kind)
+    fun nip04Encrypt() = SignerPermission(type = "nip04_encrypt")
+    fun nip04Decrypt() = SignerPermission(type = "nip04_decrypt")
+    fun nip44Encrypt() = SignerPermission(type = "nip44_encrypt")
+    fun nip44Decrypt() = SignerPermission(type = "nip44_decrypt")
+
+    fun toJson(permissions: List<SignerPermission>): String {
+        return Json.encodeToString(permissions)
+    }
+}
+
+data class ExternalSignerResult(
+    val pubkey: PublicKey,
+    val packageName: String,
+)

shared/src/commonMain/kotlin/su/reya/coop/ExternalSignerProxy.kt

@@ -0,0 +1,40 @@
+package su.reya.coop
+
+import rust.nostr.sdk.AsyncNostrSigner
+import rust.nostr.sdk.Event
+import rust.nostr.sdk.PublicKey
+import rust.nostr.sdk.UnsignedEvent
+
+class ExternalSignerProxy(
+    private val handler: ExternalSignerHandler,
+    private val currentUser: PublicKey,
+) : AsyncNostrSigner {
+    override suspend fun getPublicKeyAsync(): PublicKey {
+        return currentUser
+    }
+
+    override suspend fun signEventAsync(unsignedEvent: UnsignedEvent): Event? {
+        val signedJson = handler.signEvent(unsignedEvent, currentUser) ?: return null
+        return Event.fromJson(signedJson)
+    }
+
+    override suspend fun nip04EncryptAsync(publicKey: PublicKey, content: String): String {
+        return handler.nip04Encrypt(content, publicKey)
+            ?: throw Exception("NIP-04 encrypt rejected")
+    }
+
+    override suspend fun nip04DecryptAsync(publicKey: PublicKey, encryptedContent: String): String {
+        return handler.nip04Decrypt(encryptedContent, publicKey)
+            ?: throw Exception("NIP-04 decrypt rejected")
+    }
+
+    override suspend fun nip44EncryptAsync(publicKey: PublicKey, content: String): String {
+        return handler.nip44Encrypt(content, publicKey, currentUser)
+            ?: throw Exception("NIP-44 encrypt rejected")
+    }
+
+    override suspend fun nip44DecryptAsync(publicKey: PublicKey, payload: String): String {
+        return handler.nip44Decrypt(payload, publicKey, currentUser)
+            ?: throw Exception("NIP-44 decrypt rejected")
+    }
+}

shared/src/commonMain/kotlin/su/reya/coop/NostrViewModel.kt

@@ -44,7 +44,8 @@ import kotlin.time.Duration.Companion.seconds
 
 class NostrViewModel(
     private val nostr: Nostr,
-    private val secretStore: SecretStorage
+    private val secretStore: SecretStorage,
+    private val externalSignerHandler: ExternalSignerHandler? = null,
 ) : ViewModel() {
     private val _isNotificationBannerDismissed = MutableStateFlow(false)
     val isNotificationBannerDismissed = _isNotificationBannerDismissed.asStateFlow()
@@ -52,8 +53,8 @@ class NostrViewModel(
     private val _signerRequired = MutableStateFlow<Boolean?>(null)
     val signerRequired = _signerRequired.asStateFlow()
 
-    private val _isLoggedIn = MutableStateFlow(false)
+    private val _isBusy = MutableStateFlow(false)
-    val isLoggedIn = _isLoggedIn.asStateFlow()
+    val isBusy = _isBusy.asStateFlow()
 
     private val _isPartialProcessedGiftWrap = MutableStateFlow(false)
     val isPartialProcessedGiftWrap = _isPartialProcessedGiftWrap.asStateFlow()
@@ -371,20 +372,6 @@ class NostrViewModel(
         return keys
     }
 
-    private suspend fun createSigner(secret: String): AsyncNostrSigner {
-        return when {
-            secret.startsWith("nsec1") -> Keys.parse(secret)
-            secret.startsWith("bunker://") -> {
-                val appKeys = getOrInitAppKeys()
-                val bunker = NostrConnectUri.parse(secret)
-                val timeout = 50.seconds // or Duration.parse("50s")
-                NostrConnect(uri = bunker, appKeys, timeout, null)
-            }
-
-            else -> throw IllegalArgumentException("Invalid secret format")
-        }
-    }
-
     private suspend fun blossomUpload(file: ByteArray, contentType: String): String? {
         try {
             // Upload picture to Blossom
@@ -420,16 +407,16 @@ class NostrViewModel(
         picture: ByteArray? = null,
         contentType: String? = null
     ) {
-        _isLoggedIn.value = true
+        _isBusy.value = true
         try {
             val avatarUrl = picture?.let { blossomUpload(it, contentType ?: "image/jpeg") }
             val newMetadata = nostr.updateProfile(name, bio, avatarUrl)
             // Update the metadata state after successfully published
             updateMetadata(nostr.signer.currentUser!!, newMetadata)
+            // Update local state
+            _isBusy.value = false
         } catch (e: Exception) {
             showError("Error: ${e.message}")
-        } finally {
-            _isLoggedIn.value = false
         }
     }
 
@@ -439,7 +426,7 @@ class NostrViewModel(
         picture: ByteArray?,
         contentType: String? = null
     ) {
-        _isLoggedIn.value = true
+        _isBusy.value = true
 
         val keys = Keys.generate()
         val secret = keys.secretKey().toBech32()
@@ -448,12 +435,41 @@ class NostrViewModel(
             val avatarUrl = picture?.let { blossomUpload(it, contentType ?: "image/jpeg") }
             // Create identity
             nostr.createIdentity(keys = keys, name = name, bio, picture = avatarUrl)
+            // Persist the secret in the secret storage
+            secretStore.set("user_signer", secret)
+            // Update local states
+            _isBusy.value = false
+            _signerRequired.value = false
         } catch (e: Exception) {
             showError("Error: ${e.message}")
-        } finally {
+        }
-            secretStore.set("user_signer", secret)
+    }
-            _isLoggedIn.value = false
+
-            _signerRequired.value = false
+    private suspend fun createSigner(secret: String): AsyncNostrSigner {
+        return when {
+            secret.startsWith("nsec1") -> Keys.parse(secret)
+
+            secret.startsWith("bunker://") -> {
+                val appKeys = getOrInitAppKeys()
+                val bunker = NostrConnectUri.parse(secret)
+                val timeout = 50.seconds // or Duration.parse("50s")
+                NostrConnect(uri = bunker, appKeys, timeout, null)
+            }
+
+            secret.startsWith("nip55://") -> {
+                val handler = externalSignerHandler
+                    ?: throw IllegalStateException("External signer not available on this platform")
+
+                // Format: nip55://packageName/hexPubkey
+                val parts = secret.removePrefix("nip55://").split("/", limit = 2)
+                val packageName = parts[0]
+                val pubkey = PublicKey.parse(parts[1])
+
+                handler.setPackageName(packageName)
+                ExternalSignerProxy(handler, pubkey)
+            }
+
+            else -> throw IllegalArgumentException("Invalid secret format")
         }
     }
 
@@ -471,19 +487,59 @@ class NostrViewModel(
     }
 
     suspend fun importIdentity(secret: String) {
-        _isLoggedIn.value = true
+        _isBusy.value = true
         try {
             val signer = createSigner(secret)
+            // Update signer
             nostr.setSigner(signer)
+            // Persist the secret in the secret storage
+            secretStore.set("user_signer", secret)
+            // Update local states
+            _signerRequired.value = false
+            _isBusy.value = false
         } catch (e: Exception) {
             showError("Error: ${e.message}")
-        } finally {
-            secretStore.set("user_signer", secret)
-            _signerRequired.value = false
-            _isLoggedIn.value = false
         }
     }
 
+    suspend fun connectExternalSigner() {
+        val handler = externalSignerHandler ?: throw IllegalStateException("Signer not available")
+        _isBusy.value = true
+        try {
+            val permissions = SignerPermissions.toJson(
+                listOf(
+                    SignerPermissions.signEvent(0),
+                    SignerPermissions.signEvent(3),
+                    SignerPermissions.signEvent(10000),
+                    SignerPermissions.signEvent(10050),
+                    SignerPermissions.signEvent(10063),
+                    SignerPermissions.signEvent(22242),
+                    SignerPermissions.signEvent(30030),
+                    SignerPermissions.signEvent(30315),
+                    SignerPermissions.nip44Encrypt(),
+                    SignerPermissions.nip44Decrypt(),
+                )
+            )
+
+            val result = handler.getPublicKey(permissions) ?: throw Exception("Rejected")
+            val signer = ExternalSignerProxy(handler, result.pubkey)
+
+            // Update signer
+            nostr.setSigner(signer)
+            // Store the signer in the secret storage
+            secretStore.set("user_signer", "nip55://${result.packageName}/${result.pubkey.toHex()}")
+            // Update local states
+            _signerRequired.value = false
+            _isBusy.value = false
+        } catch (e: Exception) {
+            throw Exception("Notice: ${e.message}")
+        }
+    }
+
+    fun isExternalSignerAvailable(): Boolean {
+        return externalSignerHandler?.isAvailable() == true
+    }
+
     suspend fun useDefaultMsgRelayList() {
         try {
             val defaultRelays = nostr.getDefaultMsgRelayList()