Merge pull request #476 from greenart7c3/claude/sensitive-clipboard-keys-86dxv2

Flag nsec, ncryptsec and seed words clipboard copies as sensitive

app/src/main/java/com/greenart7c3/nostrsigner/models/Account.kt

@@ -1,15 +1,14 @@
 package com.greenart7c3.nostrsigner.models
 
-import android.content.ClipData
 import android.widget.Toast
 import androidx.compose.runtime.Immutable
 import androidx.compose.runtime.Stable
-import androidx.compose.ui.platform.ClipEntry
 import androidx.compose.ui.platform.Clipboard
 import com.greenart7c3.nostrsigner.Amber
 import com.greenart7c3.nostrsigner.DataStoreAccess
 import com.greenart7c3.nostrsigner.R
 import com.greenart7c3.nostrsigner.service.nip44v3.Nip44v3
+import com.greenart7c3.nostrsigner.ui.setSensitiveClip
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.hexToByteArray
@@ -120,11 +119,7 @@ class Account(
             didBackup = true
             val nsec = getNsec()
             Amber.instance.applicationIOScope.launch(Dispatchers.Main) {
-                clipboardManager.setClipEntry(
-                    ClipEntry(
-                        ClipData.newPlainText("", nsec),
-                    ),
-                )
+                clipboardManager.setSensitiveClip("", nsec)
 
                 Toast.makeText(
                     Amber.instance,

app/src/main/java/com/greenart7c3/nostrsigner/ui/SensitiveClipboard.kt

@@ -0,0 +1,73 @@
+package com.greenart7c3.nostrsigner.ui
+
+import android.content.ClipData
+import android.content.ClipDescription
+import android.os.Build
+import android.os.PersistableBundle
+import androidx.compose.ui.platform.ClipEntry
+import androidx.compose.ui.platform.Clipboard
+import com.greenart7c3.nostrsigner.Amber
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+
+/** How long a copied secret stays on the clipboard before it is cleared. */
+const val SENSITIVE_CLIPBOARD_CLEAR_DELAY_MS = 60_000L
+
+/**
+ * Creates a [ClipData] flagged as sensitive so the system (Android 13+) avoids
+ * showing the copied content in clipboard previews. Use this for secrets such as
+ * the nsec, ncryptsec and seed words.
+ */
+fun newSensitivePlainText(label: CharSequence, text: CharSequence): ClipData {
+    val clipData = ClipData.newPlainText(label, text)
+    val extras = PersistableBundle().apply {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            putBoolean(ClipDescription.EXTRA_IS_SENSITIVE, true)
+        } else {
+            putBoolean("android.content.extra.IS_SENSITIVE", true)
+        }
+    }
+    clipData.description.extras = extras
+    return clipData
+}
+
+/**
+ * Copies a secret to the clipboard flagged as sensitive content and schedules it
+ * to be cleared after [clearAfterMillis]. The clipboard is only cleared if it
+ * still contains the copied secret, so anything the user copies afterwards is
+ * left untouched.
+ */
+suspend fun Clipboard.setSensitiveClip(
+    label: CharSequence,
+    text: CharSequence,
+    scope: CoroutineScope = Amber.instance.applicationIOScope,
+    clearAfterMillis: Long = SENSITIVE_CLIPBOARD_CLEAR_DELAY_MS,
+) {
+    setClipEntry(ClipEntry(newSensitivePlainText(label, text)))
+    scheduleSensitiveClear(text, scope, clearAfterMillis)
+}
+
+private fun Clipboard.scheduleSensitiveClear(
+    copiedValue: CharSequence,
+    scope: CoroutineScope,
+    delayMillis: Long,
+) {
+    scope.launch {
+        delay(delayMillis)
+        val currentText = getClipEntry()?.clipData?.let { clip ->
+            if (clip.itemCount > 0) clip.getItemAt(0).text?.toString() else null
+        }
+        if (currentText == copiedValue.toString()) {
+            clearClipboard()
+        }
+    }
+}
+
+private suspend fun Clipboard.clearClipboard() {
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
+        nativeClipboard.clearPrimaryClip()
+    } else {
+        setClipEntry(ClipEntry(ClipData.newPlainText("", "")))
+    }
+}

app/src/main/java/com/greenart7c3/nostrsigner/ui/actions/AccountBackupScreen.kt

@@ -1,7 +1,6 @@
 package com.greenart7c3.nostrsigner.ui.actions
 
 import android.app.Activity
-import android.content.ClipData
 import android.content.Context
 import android.view.WindowManager
 import android.widget.Toast
@@ -70,7 +69,6 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.autofill.ContentType
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.platform.ClipEntry
 import androidx.compose.ui.platform.Clipboard
 import androidx.compose.ui.platform.LocalClipboard
 import androidx.compose.ui.platform.LocalContext
@@ -107,6 +105,7 @@ import com.greenart7c3.nostrsigner.ui.components.IconRow
 import com.greenart7c3.nostrsigner.ui.components.MarkdownText
 import com.greenart7c3.nostrsigner.ui.components.SeedWordsPage
 import com.greenart7c3.nostrsigner.ui.navigation.Route
+import com.greenart7c3.nostrsigner.ui.setSensitiveClip
 import com.greenart7c3.nostrsigner.ui.theme.Size35dp
 import com.greenart7c3.nostrsigner.ui.theme.fromHex
 import com.vitorpamplona.quartz.nip06KeyDerivation.Nip06
@@ -797,7 +796,7 @@ private fun encryptCopyNSec(
                 account.didBackup = true
                 onBackupDone()
                 Amber.instance.applicationIOScope.launch(Dispatchers.Main) {
-                    clipboardManager.setClipEntry(ClipEntry(ClipData.newPlainText("", key)))
+                    clipboardManager.setSensitiveClip("", key)
                     Toast.makeText(context, context.getString(R.string.secret_key_copied_to_clipboard), Toast.LENGTH_SHORT).show()
                 }
                 onLoading(false)

app/src/main/java/com/greenart7c3/nostrsigner/ui/components/SeedWordsPage.kt

@@ -1,6 +1,5 @@
 package com.greenart7c3.nostrsigner.ui.components
 
-import android.content.ClipData
 import android.view.WindowManager
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
@@ -20,7 +19,6 @@ import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.ClipEntry
 import androidx.compose.ui.platform.LocalClipboard
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.font.FontWeight
@@ -32,6 +30,7 @@ import androidx.lifecycle.LifecycleEventObserver
 import androidx.lifecycle.compose.LocalLifecycleOwner
 import com.greenart7c3.nostrsigner.Amber
 import com.greenart7c3.nostrsigner.R
+import com.greenart7c3.nostrsigner.ui.setSensitiveClip
 import com.greenart7c3.nostrsigner.ui.verticalScrollbar
 import kotlinx.coroutines.launch
 
@@ -74,11 +73,7 @@ fun SeedWordsPage(
             AmberButton(
                 onClick = {
                     scope.launch {
-                        clipboardManager.setClipEntry(
-                            ClipEntry(
-                                ClipData.newPlainText("", seedWords.joinToString(" ")),
-                            ),
-                        )
+                        clipboardManager.setSensitiveClip("", seedWords.joinToString(" "))
                     }
                 },
                 text = stringResource(R.string.copy_to_clipboard),