new feature: long press OTP card in OTP codes page to export or update seed

2026-09-26 20:43:14 +05:00
parent 41e7bc70e9
commit 1886113ae7
10 changed files with 543 additions and 99 deletions
@@ -50,6 +50,11 @@ class MibLoginFlow(private val credentialStore: CredentialStore) {
        }
        .build()

+    /** Swap the seed used for silent re-login after the user replaces it on the OTP screen. */
+    fun updateOtpSeed(otpSeed: String) {
+        if (storedOtpSeed != null) storedOtpSeed = otpSeed
+    }
+
    // ─── Public entry point ───────────────────────────────────────────────────

    /**
@@ -1,14 +1,25 @@
 package sh.sar.basedbank.ui.home

+import android.app.Activity
 import android.content.ClipData
+import android.content.ClipDescription
 import android.content.ClipboardManager
 import android.content.Context
+import android.content.DialogInterface
+import android.content.Intent
+import android.graphics.Bitmap
+import android.graphics.Color
 import android.os.Build
 import android.os.Bundle
+import android.os.PersistableBundle
+import android.text.Editable
+import android.text.TextWatcher
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.widget.PopupMenu
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.lifecycleScope
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -19,14 +30,22 @@ import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import com.google.android.material.color.MaterialColors
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import com.google.zxing.BarcodeFormat
+import com.google.zxing.EncodeHintType
+import com.google.zxing.qrcode.QRCodeWriter
+import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel
 import sh.sar.basedbank.BasedBankApp
 import sh.sar.basedbank.R
 import sh.sar.basedbank.api.bml.BmlAccountClient
 import sh.sar.basedbank.api.mib.MibProfileClient
 import sh.sar.basedbank.api.mib.MibLoginFlow
+import sh.sar.basedbank.databinding.DialogOtpExportSeedBinding
+import sh.sar.basedbank.databinding.DialogOtpUpdateSeedBinding
 import sh.sar.basedbank.databinding.FragmentOtpBinding
 import sh.sar.basedbank.databinding.ItemOtpCardBinding
 import sh.sar.basedbank.util.CredentialStore
+import sh.sar.basedbank.util.OtpauthParser
 import sh.sar.basedbank.util.Totp

 class OtpFragment : Fragment() {
@@ -34,7 +53,35 @@ class OtpFragment : Fragment() {
    private var _binding: FragmentOtpBinding? = null
    private val binding get() = _binding!!

-    private data class OtpEntry(val bank: String, val name: String?, val seed: String)
+    private data class OtpEntry(
+        val bank: String, val loginId: String, val account: String, val name: String?, val seed: String
+    )
+
+    private val entries = mutableListOf<OtpEntry>()
+    private var adapter: OtpAdapter? = null
+
+    /** Seed field of the open "Update seed" dialog, filled by the QR scanner result. */
+    private var scanTarget: android.widget.EditText? = null
+
+    private val qrLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
+        if (result.resultCode != Activity.RESULT_OK) return@registerForActivityResult
+        val raw = result.data?.getStringExtra(QrScannerActivity.EXTRA_QR_CONTENT) ?: return@registerForActivityResult
+        val target = scanTarget ?: return@registerForActivityResult
+        val found = OtpauthParser.parse(raw)
+        when {
+            found.isEmpty() -> Toast.makeText(requireContext(), "No OTP data found in QR", Toast.LENGTH_SHORT).show()
+            found.size == 1 -> target.setText(found[0].secret)
+            else -> {
+                val labels = found.map { e ->
+                    if (e.issuer.isNotBlank()) "${e.issuer} (${e.name})" else e.name.ifBlank { e.secret.take(8) + "…" }
+                }.toTypedArray()
+                MaterialAlertDialogBuilder(requireContext())
+                    .setTitle("Choose account")
+                    .setItems(labels) { _, i -> target.setText(found[i].secret) }
+                    .show()
+            }
+        }
+    }

    private inner class OtpAdapter(private val entries: List<OtpEntry>) :
        RecyclerView.Adapter<OtpAdapter.VH>() {
@@ -56,6 +103,8 @@ class OtpFragment : Fragment() {
            )
            update(b, entry.seed)
            b.root.setOnClickListener { copyCode(it.context, b.tvOtpCode.text, "OTP copied") }
+            // Long-press opens the seed menu (export / update)
+            b.root.setOnLongClickListener { showSeedMenu(it, holder.bindingAdapterPosition); true }
            b.btnCopyOtp.setOnClickListener { copyCode(it.context, b.tvOtpCode.text, "OTP copied") }
            b.btnCopyNextOtp.setOnClickListener { copyCode(it.context, b.tvNextOtpCode.text, "Next OTP copied") }
        }
@@ -91,6 +140,170 @@ class OtpFragment : Fragment() {
        }
    }

+    private fun showSeedMenu(anchor: View, position: Int) {
+        if (position == RecyclerView.NO_POSITION) return
+        val popup = PopupMenu(anchor.context, anchor)
+        popup.menu.add(0, 1, 0, "Export seed")
+        popup.menu.add(0, 2, 1, "Update seed")
+        popup.setOnMenuItemClickListener { item ->
+            val entry = entries.getOrNull(position) ?: return@setOnMenuItemClickListener false
+            when (item.itemId) {
+                1 -> showExportDialog(entry)
+                2 -> showUpdateDialog(position)
+            }
+            true
+        }
+        popup.show()
+    }
+
+    private fun entryTitle(entry: OtpEntry) = "${entry.bank} · ${entry.name ?: entry.account}"
+
+    // ── Export ───────────────────────────────────────────────────────────────
+
+    private fun showExportDialog(entry: OtpEntry) {
+        val ctx = requireContext()
+        val d = DialogOtpExportSeedBinding.inflate(layoutInflater)
+        val uri = OtpauthParser.buildUri(entry.bank, entry.seed)
+        d.tvSeed.text = entry.seed.chunked(4).joinToString(" ")
+        renderQr(uri, (220 * resources.displayMetrics.density).toInt())?.let { d.ivSeedQr.setImageBitmap(it) }
+        d.btnCopySeed.setOnClickListener { copySensitive(ctx, entry.seed, "Seed copied") }
+        MaterialAlertDialogBuilder(ctx)
+            .setTitle(entryTitle(entry))
+            .setView(d.root)
+            .setPositiveButton("Done", null)
+            .show()
+    }
+
+    private fun renderQr(content: String, size: Int): Bitmap? = try {
+        val hints = mapOf(
+            EncodeHintType.MARGIN to 0,
+            EncodeHintType.ERROR_CORRECTION to ErrorCorrectionLevel.M
+        )
+        val matrix = QRCodeWriter().encode(content, BarcodeFormat.QR_CODE, size, size, hints)
+        val pixels = IntArray(size * size) { i -> if (matrix[i % size, i / size]) Color.BLACK else Color.WHITE }
+        Bitmap.createBitmap(pixels, size, size, Bitmap.Config.ARGB_8888)
+    } catch (_: Exception) { null }
+
+    /** Copy a secret, flagged sensitive so Android 13+ hides it in the clipboard preview. */
+    private fun copySensitive(context: Context, text: String, message: String) {
+        val clip = ClipData.newPlainText("OTP seed", text)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            clip.description.extras = PersistableBundle().apply {
+                putBoolean(ClipDescription.EXTRA_IS_SENSITIVE, true)
+            }
+        }
+        val clipboard = context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
+        clipboard.setPrimaryClip(clip)
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU) {
+            Toast.makeText(context, message, Toast.LENGTH_SHORT).show()
+        }
+    }
+
+    // ── Update ───────────────────────────────────────────────────────────────
+
+    private fun showUpdateDialog(position: Int) {
+        val entry = entries.getOrNull(position) ?: return
+        val ctx = requireContext()
+        val d = DialogOtpUpdateSeedBinding.inflate(layoutInflater)
+        d.tvSeedWarning.text = "Saving will replace the current seed for this login, and the old one " +
+            "can't be recovered. If you might still need it, export it first."
+
+        var newSeed: String? = null
+        // Same behaviour as the sign-in screen's preview card
+        val preview = d.cardOtp
+        preview.root.setOnClickListener { copyCode(it.context, preview.tvOtpCode.text, "OTP copied") }
+        fun refreshPreview() {
+            val seed = newSeed
+            try {
+                if (seed == null) throw IllegalArgumentException()
+                preview.tvOtpCode.text = Totp.generate(seed)
+                preview.tvNextOtpCode.text = Totp.generate(seed, periodOffset = 1)
+                preview.otpTimer.max = 30
+                preview.otpTimer.progress = 30 - (System.currentTimeMillis() / 1000L % 30).toInt()
+                preview.root.visibility = View.VISIBLE
+            } catch (_: Exception) {
+                preview.root.visibility = View.INVISIBLE
+            }
+        }
+
+        val dialog = MaterialAlertDialogBuilder(ctx)
+            .setTitle("Update seed · ${entry.bank}")
+            .setView(d.root)
+            .setPositiveButton("Replace", null)
+            .setNegativeButton("Cancel", null)
+            .create()
+
+        fun validate() {
+            val raw = d.etNewSeed.text?.toString().orEmpty()
+            newSeed = OtpauthParser.resolveSecret(raw)
+            d.tilNewSeed.error = when {
+                raw.isBlank() -> null
+                newSeed == null -> "Not a valid TOTP seed"
+                newSeed == entry.seed -> "This is already the current seed"
+                else -> null
+            }
+            if (newSeed == entry.seed) newSeed = null
+            dialog.getButton(DialogInterface.BUTTON_POSITIVE)?.isEnabled = newSeed != null
+            refreshPreview()
+        }
+
+        d.etNewSeed.addTextChangedListener(object : TextWatcher {
+            override fun afterTextChanged(s: Editable?) = validate()
+            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
+            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
+        })
+        d.btnScanNewSeed.setOnClickListener {
+            scanTarget = d.etNewSeed
+            qrLauncher.launch(Intent(ctx, QrScannerActivity::class.java))
+        }
+
+        val ticker = viewLifecycleOwner.lifecycleScope.launch {
+            while (isActive) { refreshPreview(); delay(1_000) }
+        }
+        dialog.setOnDismissListener {
+            ticker.cancel()
+            if (scanTarget === d.etNewSeed) scanTarget = null
+        }
+        dialog.setOnShowListener {
+            val replace = dialog.getButton(DialogInterface.BUTTON_POSITIVE)
+            replace.isEnabled = false
+            replace.setOnClickListener {
+                val seed = newSeed ?: return@setOnClickListener
+                confirmReplace(entry) {
+                    saveSeed(position, seed)
+                    dialog.dismiss()
+                }
+            }
+        }
+        dialog.show()
+    }
+
+    private fun confirmReplace(entry: OtpEntry, onConfirm: () -> Unit) {
+        MaterialAlertDialogBuilder(requireContext())
+            .setTitle("Delete old seed?")
+            .setMessage("The current seed for ${entryTitle(entry)} will be replaced and can't be " +
+                "recovered afterwards.")
+            .setPositiveButton("Replace") { _, _ -> onConfirm() }
+            .setNegativeButton("Cancel", null)
+            .show()
+    }
+
+    private fun saveSeed(position: Int, seed: String) {
+        val entry = entries.getOrNull(position) ?: return
+        val store = CredentialStore(requireContext())
+        when (entry.bank) {
+            "MIB" -> {
+                store.updateMibOtpSeed(entry.loginId, seed)
+                // The live flow keeps the seed in memory for silent re-login
+                (requireActivity().application as BasedBankApp).mibFlowFor(entry.loginId).updateOtpSeed(seed)
+            }
+            "BML" -> store.updateBmlOtpSeed(entry.loginId, seed)
+        }
+        entries[position] = entry.copy(seed = seed)
+        adapter?.notifyItemChanged(position)
+        Toast.makeText(requireContext(), "Seed updated", Toast.LENGTH_SHORT).show()
+    }
+
    private fun copyCode(context: Context, text: CharSequence, message: String) {
        val code = text.toString().replace(" ", "")
        if (code.isEmpty() || code.contains('-')) return
@@ -115,16 +328,19 @@ class OtpFragment : Fragment() {
        for (loginId in store.getMibLoginIds()) {
            val creds = store.loadMibCredentials(loginId) ?: continue
            val name = store.loadMibFullName(loginId)
-            tagged.add(CredentialStore.loginKey("mib", loginId) to OtpEntry("MIB", name, creds.otpSeed))
+            tagged.add(CredentialStore.loginKey("mib", loginId) to
+                OtpEntry("MIB", loginId, creds.username, name, creds.otpSeed))
        }
        for (loginId in store.getBmlLoginIds()) {
            val creds = store.loadBmlCredentials(loginId) ?: continue
            val name = store.loadBmlUserProfile(loginId)?.fullName
-            tagged.add(CredentialStore.loginKey("bml", loginId) to OtpEntry("BML", name?.takeIf { it.isNotBlank() }, creds.otpSeed))
+            tagged.add(CredentialStore.loginKey("bml", loginId) to
+                OtpEntry("BML", loginId, creds.username, name?.takeIf { it.isNotBlank() }, creds.otpSeed))
        }
-        val entries = tagged.sortedBy { rank(it.first) }.map { it.second }.toMutableList()
+        entries.clear()
+        entries.addAll(tagged.sortedBy { rank(it.first) }.map { it.second })

-        val adapter = OtpAdapter(entries)
+        val adapter = OtpAdapter(entries).also { this.adapter = it }
        binding.recyclerView.layoutManager = LinearLayoutManager(requireContext())
        binding.recyclerView.adapter = adapter
        binding.emptyState.visibility = if (entries.isEmpty()) View.VISIBLE else View.GONE
@@ -147,8 +363,7 @@ class OtpFragment : Fragment() {
                            mobile = profile.mobile,
                            enrolled = profile.enrolled
                        ))
-                        val seed = store.loadMibCredentials(loginId)?.otpSeed
-                        val idx = entries.indexOfFirst { it.seed == seed }
+                        val idx = entries.indexOfFirst { it.bank == "MIB" && it.loginId == loginId }
                        if (idx >= 0) { entries[idx] = entries[idx].copy(name = profile.fullName); changed = true }
                    }
                }
@@ -168,8 +383,7 @@ class OtpFragment : Fragment() {
                            idCard = info.idCard,
                            birthdate = info.birthdate
                        ))
-                        val seed = store.loadBmlCredentials(loginId)?.otpSeed
-                        val idx = entries.indexOfFirst { it.seed == seed }
+                        val idx = entries.indexOfFirst { it.bank == "BML" && it.loginId == loginId }
                        if (idx >= 0) { entries[idx] = entries[idx].copy(name = info.fullName); changed = true }
                    }
                }
@@ -192,6 +406,8 @@ class OtpFragment : Fragment() {

    override fun onDestroyView() {
        super.onDestroyView()
+        adapter = null
+        scanTarget = null
        _binding = null
    }
 }
@@ -129,8 +129,8 @@ class CredentialsFragment : Fragment() {
            qrLauncher.launch(Intent(requireContext(), QrScannerActivity::class.java))
        }

-        binding.cardOtp.setOnClickListener {
-            val code = binding.tvOtpCode.text.toString().replace(" ", "")
+        binding.cardOtp.root.setOnClickListener {
+            val code = binding.cardOtp.tvOtpCode.text.toString().replace(" ", "")
            if (code.isNotEmpty()) {
                val clipboard = requireContext().getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
                clipboard.setPrimaryClip(ClipData.newPlainText("OTP", code))
@@ -198,12 +198,12 @@ class CredentialsFragment : Fragment() {
        val otpSeedRaw = binding.etOtpSeed.text.toString().trim()
        val seed = resolveOtpSeed(otpSeedRaw)
        if (seed.isEmpty()) {
-            binding.cardOtp.visibility = View.INVISIBLE
+            binding.cardOtp.root.visibility = View.INVISIBLE
            return
        }
        val password = binding.etPassword.text.toString()
        if (otpSeedRaw == password || seed.matches(Regex("\\d{6}"))) {
-            binding.cardOtp.visibility = View.INVISIBLE
+            binding.cardOtp.root.visibility = View.INVISIBLE
            return
        }
        try {
@@ -211,13 +211,13 @@ class CredentialsFragment : Fragment() {
            val secondsInPeriod = (System.currentTimeMillis() / 1000L % 30).toInt()
            val remaining = 30 - secondsInPeriod

-            binding.tvOtpCode.text = otp
-            binding.tvNextOtpCode.text = Totp.generate(seed, periodOffset = 1)
-            binding.otpTimer.max = 30
-            binding.otpTimer.progress = remaining
-            binding.cardOtp.visibility = View.VISIBLE
+            binding.cardOtp.tvOtpCode.text = otp
+            binding.cardOtp.tvNextOtpCode.text = Totp.generate(seed, periodOffset = 1)
+            binding.cardOtp.otpTimer.max = 30
+            binding.cardOtp.otpTimer.progress = remaining
+            binding.cardOtp.root.visibility = View.VISIBLE
        } catch (e: Exception) {
-            binding.cardOtp.visibility = View.INVISIBLE
+            binding.cardOtp.root.visibility = View.INVISIBLE
        }
    }

@@ -100,6 +100,11 @@ class CredentialStore(context: Context) {
            .apply()
    }

+    /** Replaces only the stored TOTP seed; the old seed is overwritten and cannot be recovered. */
+    fun updateMibOtpSeed(loginId: String, otpSeed: String) {
+        prefs.edit().putString("mib_${loginId}_enc_otp_seed", encrypt(otpSeed, getOrCreateKey())).apply()
+    }
+
    fun loadMibCredentials(loginId: String): MibCredentials? {
        val key = getOrCreateKey()
        val encHash = prefs.getString("mib_${loginId}_enc_password_hash", null) ?: return null
@@ -230,6 +235,11 @@ class CredentialStore(context: Context) {
            .apply()
    }

+    /** Replaces only the stored TOTP seed; the old seed is overwritten and cannot be recovered. */
+    fun updateBmlOtpSeed(loginId: String, otpSeed: String) {
+        prefs.edit().putString("bml_${loginId}_enc_otp_seed", encrypt(otpSeed, getOrCreateKey())).apply()
+    }
+
    fun loadBmlCredentials(loginId: String): BmlCredentials? {
        val key = getOrCreateKey()
        val encUsername = prefs.getString("bml_${loginId}_enc_username", null) ?: return null
@@ -13,6 +13,27 @@ object OtpauthParser {
        else -> emptyList()
    }

+    /**
+     * Normalise user input into a bare Base32 secret: accepts an otpauth:// link or a raw
+     * secret with spaces/dashes. Returns null if the result isn't usable as a TOTP seed.
+     */
+    fun resolveSecret(input: String): String? {
+        val raw = input.trim()
+        val secret = if (raw.startsWith("otpauth://")) Uri.parse(raw).getQueryParameter("secret") ?: return null else raw
+        val clean = secret.replace("\\s".toRegex(), "").replace("-", "").trimEnd('=').uppercase()
+        if (clean.isEmpty() || !clean.all { it in 'A'..'Z' || it in '2'..'7' }) return null
+        // Too short to be a real seed, e.g. a pasted 6-digit OTP code
+        if (clean.length < 8) return null
+        return clean
+    }
+
+    /**
+     * Build the shortest otpauth://totp link authenticator apps accept: just a label and the
+     * secret. SHA1, 6 digits and a 30s period are the spec defaults, so they're left out.
+     */
+    fun buildUri(label: String, secret: String): String =
+        "otpauth://totp/" + Uri.encode(label) + "?secret=$secret"
+
    private fun parseStandard(raw: String): OtpEntry? {
        val uri = Uri.parse(raw)
        val secret = uri.getQueryParameter("secret") ?: return null
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8"?>
+<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="wrap_content">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:gravity="center_horizontal"
+        android:orientation="vertical"
+        android:paddingHorizontal="24dp"
+        android:paddingTop="8dp">
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="16dp"
+            android:text="Scan this with your authenticator app, or copy the seed. Please keep it private, since anyone who has it can generate your OTP codes."
+            android:textAppearance="?attr/textAppearanceBodySmall"
+            android:textColor="?attr/colorOnSurfaceVariant" />
+
+        <!-- Always black-on-white so scanners read it in dark mode too -->
+        <com.google.android.material.card.MaterialCardView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            app:cardBackgroundColor="@android:color/white"
+            app:cardCornerRadius="16dp"
+            app:strokeWidth="0dp">
+
+            <ImageView
+                android:id="@+id/ivSeedQr"
+                android:layout_width="220dp"
+                android:layout_height="220dp"
+                android:layout_margin="12dp"
+                android:contentDescription="OTP seed QR code" />
+
+        </com.google.android.material.card.MaterialCardView>
+
+        <TextView
+            android:id="@+id/tvSeed"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp"
+            android:fontFamily="monospace"
+            android:gravity="center"
+            android:textAppearance="?attr/textAppearanceTitleMedium"
+            android:textColor="?attr/colorOnSurface"
+            android:textIsSelectable="true" />
+
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/btnCopySeed"
+            style="@style/Widget.Material3.Button.TonalButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="Copy seed"
+            app:icon="@drawable/ic_copy" />
+
+    </LinearLayout>
+
+</ScrollView>
@@ -0,0 +1,98 @@
+<?xml version="1.0" encoding="utf-8"?>
+<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="wrap_content">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:paddingHorizontal="24dp"
+        android:paddingTop="8dp">
+
+        <!-- Warning: the old seed is overwritten -->
+        <com.google.android.material.card.MaterialCardView
+            style="@style/Widget.Material3.CardView.Filled"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="16dp"
+            app:cardBackgroundColor="?attr/colorErrorContainer"
+            app:cardCornerRadius="16dp">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:padding="12dp">
+
+                <ImageView
+                    android:layout_width="20dp"
+                    android:layout_height="20dp"
+                    android:layout_marginEnd="12dp"
+                    android:importantForAccessibility="no"
+                    android:src="@drawable/ic_info"
+                    app:tint="?attr/colorOnErrorContainer" />
+
+                <TextView
+                    android:id="@+id/tvSeedWarning"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:textAppearance="?attr/textAppearanceBodySmall"
+                    android:textColor="?attr/colorOnErrorContainer" />
+
+            </LinearLayout>
+
+        </com.google.android.material.card.MaterialCardView>
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical">
+
+            <com.google.android.material.textfield.TextInputLayout
+                android:id="@+id/tilNewSeed"
+                style="@style/Widget.Material3.TextInputLayout.OutlinedBox"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:hint="New OTP seed"
+                app:helperText="Base32 secret or otpauth:// link">
+
+                <com.google.android.material.textfield.TextInputEditText
+                    android:id="@+id/etNewSeed"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:fontFamily="monospace"
+                    android:imeOptions="actionDone"
+                    android:inputType="textNoSuggestions|textVisiblePassword"
+                    android:singleLine="true" />
+
+            </com.google.android.material.textfield.TextInputLayout>
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/btnScanNewSeed"
+                style="@style/Widget.Material3.Button.IconButton"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginStart="8dp"
+                android:contentDescription="@string/scan_otp_qr"
+                android:tooltipText="@string/scan_otp_qr"
+                app:icon="@drawable/ic_qr_scan" />
+
+        </LinearLayout>
+
+        <!-- Live preview of the new seed's code, same card as the sign-in screen -->
+        <include
+            android:id="@+id/cardOtp"
+            layout="@layout/view_otp_preview"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp" />
+
+    </LinearLayout>
+
+</ScrollView>
@@ -130,89 +130,13 @@
                android:maxLength="6" />
        </com.google.android.material.textfield.TextInputLayout>

-        <com.google.android.material.card.MaterialCardView
+        <include
            android:id="@+id/cardOtp"
+            layout="@layout/view_otp_preview"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
-            android:layout_marginBottom="8dp"
-            android:visibility="invisible"
-            android:clickable="true"
-            android:focusable="true"
-            app:cardBackgroundColor="?attr/colorSecondaryContainer"
-            app:cardCornerRadius="12dp"
-            app:cardElevation="0dp">
-
-            <LinearLayout
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:orientation="horizontal"
-                android:paddingHorizontal="16dp"
-                android:paddingVertical="12dp"
-                android:gravity="center_vertical">
-
-                <LinearLayout
-                    android:layout_width="0dp"
-                    android:layout_height="wrap_content"
-                    android:layout_weight="1"
-                    android:orientation="vertical">
-
-                    <TextView
-                        android:layout_width="wrap_content"
-                        android:layout_height="wrap_content"
-                        android:text="Current OTP"
-                        android:textAppearance="?attr/textAppearanceLabelSmall"
-                        android:textColor="?attr/colorOnSecondaryContainer" />
-
-                    <TextView
-                        android:id="@+id/tvOtpCode"
-                        android:layout_width="wrap_content"
-                        android:layout_height="wrap_content"
-                        android:textAppearance="?attr/textAppearanceHeadlineSmall"
-                        android:textColor="?attr/colorOnSecondaryContainer"
-                        android:letterSpacing="0.15"
-                        android:fontFamily="monospace" />
-
-                </LinearLayout>
-
-                <LinearLayout
-                    android:layout_width="wrap_content"
-                    android:layout_height="wrap_content"
-                    android:layout_marginEnd="16dp"
-                    android:orientation="vertical"
-                    android:gravity="end"
-                    android:alpha="0.7">
-
-                    <TextView
-                        android:layout_width="wrap_content"
-                        android:layout_height="wrap_content"
-                        android:text="Next"
-                        android:textAppearance="?attr/textAppearanceLabelSmall"
-                        android:textColor="?attr/colorOnSecondaryContainer" />
-
-                    <TextView
-                        android:id="@+id/tvNextOtpCode"
-                        android:layout_width="wrap_content"
-                        android:layout_height="wrap_content"
-                        android:textAppearance="?attr/textAppearanceTitleMedium"
-                        android:textColor="?attr/colorOnSecondaryContainer"
-                        android:letterSpacing="0.1"
-                        android:fontFamily="monospace" />
-
-                </LinearLayout>
-
-                <com.google.android.material.progressindicator.CircularProgressIndicator
-                    android:id="@+id/otpTimer"
-                    android:layout_width="32dp"
-                    android:layout_height="32dp"
-                    app:indicatorSize="32dp"
-                    app:trackThickness="3dp"
-                    app:indicatorColor="?attr/colorOnSecondaryContainer"
-                    app:trackColor="?attr/colorSecondaryContainer"
-                    android:indeterminate="false" />
-
-            </LinearLayout>
-        </com.google.android.material.card.MaterialCardView>
+            android:layout_marginBottom="8dp" />

        <TextView
            android:id="@+id/tvError"
@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Live TOTP preview card, shared by the sign-in screen and the OTP screen's "Update seed" dialog -->
+<com.google.android.material.card.MaterialCardView
+    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="wrap_content"
+    android:visibility="invisible"
+    android:clickable="true"
+    android:focusable="true"
+    app:cardBackgroundColor="?attr/colorSecondaryContainer"
+    app:cardCornerRadius="12dp"
+    app:cardElevation="0dp">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:paddingHorizontal="16dp"
+        android:paddingVertical="12dp"
+        android:gravity="center_vertical">
+
+        <LinearLayout
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:orientation="vertical">
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Current OTP"
+                android:textAppearance="?attr/textAppearanceLabelSmall"
+                android:textColor="?attr/colorOnSecondaryContainer" />
+
+            <TextView
+                android:id="@+id/tvOtpCode"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:textAppearance="?attr/textAppearanceHeadlineSmall"
+                android:textColor="?attr/colorOnSecondaryContainer"
+                android:letterSpacing="0.15"
+                android:fontFamily="monospace" />
+
+        </LinearLayout>
+
+        <LinearLayout
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginEnd="16dp"
+            android:orientation="vertical"
+            android:gravity="end"
+            android:alpha="0.7">
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Next"
+                android:textAppearance="?attr/textAppearanceLabelSmall"
+                android:textColor="?attr/colorOnSecondaryContainer" />
+
+            <TextView
+                android:id="@+id/tvNextOtpCode"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:textAppearance="?attr/textAppearanceTitleMedium"
+                android:textColor="?attr/colorOnSecondaryContainer"
+                android:letterSpacing="0.1"
+                android:fontFamily="monospace" />
+
+        </LinearLayout>
+
+        <com.google.android.material.progressindicator.CircularProgressIndicator
+            android:id="@+id/otpTimer"
+            android:layout_width="32dp"
+            android:layout_height="32dp"
+            app:indicatorSize="32dp"
+            app:trackThickness="3dp"
+            app:indicatorColor="?attr/colorOnSecondaryContainer"
+            app:trackColor="?attr/colorSecondaryContainer"
+            android:indeterminate="false" />
+
+    </LinearLayout>
+</com.google.android.material.card.MaterialCardView>
@@ -21,6 +21,29 @@ Each card shows:

 Tapping anywhere on the card also copies the current code. If no logins have a seed, an empty-state message is shown instead.

+---
+
+## Seed Actions
+
+Long-pressing a card opens a menu with:
+
+### Export seed
+
+A dialog titled `{bank} · {name}` showing:
+- A QR code of a minimal `otpauth://totp/{BANK}?secret=…` link (e.g. `otpauth://totp/BML?secret=…`), always drawn black-on-white so it scans in dark mode. No username or issuer is included, and algorithm, digits and period are left out because SHA1, 6 and 30s are the spec defaults. Export is single-account only; `otpauth-migration://` is supported for import but never produced.
+- The Base32 seed in groups of 4 (selectable text)
+- A **Copy seed** button. The copy is flagged `EXTRA_IS_SENSITIVE`, so Android 13+ hides the value in the clipboard preview.
+
+### Update seed
+
+Replaces the stored seed for that login, e.g. after re-enrolling the authenticator with the bank.
+- A red warning banner explains that the old seed is deleted permanently.
+- The new seed can be typed or pasted (raw Base32 or an `otpauth://` link) or scanned with the QR button. Scans that contain several accounts (`otpauth-migration://`) ask which one to use.
+- Once the input is a valid seed, a live preview shows its current and next code with a countdown so the user can check it against the bank before saving. The preview is the same card as the sign-in screen (`view_otp_preview.xml`, shared by both), and tapping it copies the code. Input that isn't valid Base32, is shorter than 8 characters (such as a pasted 6-digit code), or matches the current seed disables **Replace**.
+- **Replace** asks for confirmation ("Delete old seed?"). Confirming calls `CredentialStore.updateMibOtpSeed()` / `updateBmlOtpSeed()`, which overwrite only the encrypted seed. For MIB it also calls `MibLoginFlow.updateOtpSeed()` so silent re-login uses the new seed.
+
+The username, password and sessions are not touched. Other places that need an OTP (transfers, QR pay, pay with card) read the seed from `CredentialStore` each time, so they pick up the new seed immediately.
+
 ### Algorithm

 Standard RFC 6238 TOTP:
@@ -58,7 +81,7 @@ The OTP screen is informational — the user copies the displayed code manually

 ## Security

-The TOTP seeds are stored encrypted in `CredentialStore`. They are never logged or included in error reports.
+The TOTP seeds are stored encrypted in `CredentialStore`. They are never logged or included in error reports. They leave the app only when the user chooses **Export seed**.

 ---