fix(security): apply iOS audit parity fixes (#709)

Co-authored-by: CC <cc@ggg.local>

app/src/main/java/com/bitchat/android/geohash/LocationChannelManager.kt

@@ -539,6 +539,7 @@ class LocationChannelManager private constructor(private val context: Context) {
     fun clearPersistedChannel() {
         dataManager?.clearLastGeohashChannel()
         _selectedChannel.value = ChannelID.Mesh
+        _teleported.value = false
         Log.d(TAG, "Cleared persisted channel selection")
     }
 

app/src/main/java/com/bitchat/android/noise/NoiseSession.kt

@@ -572,7 +572,12 @@ class NoiseSession(
                 }
                 
                 val (extractedNonce, ciphertext) = nonceAndCiphertext
-                
+
+                if (ciphertext.size < receiveCipher!!.macLength) {
+                    Log.w(TAG, "Ciphertext too short: ${ciphertext.size} < ${receiveCipher!!.macLength}")
+                    throw SessionError.DecryptionFailed
+                }
+
                 // Validate nonce with sliding window replay protection
                 if (!isValidNonce(extractedNonce, highestReceivedNonce, replayWindow)) {
                     Log.w(TAG, "Replay attack detected: nonce $extractedNonce rejected for $peerID")

app/src/main/java/com/bitchat/android/nostr/NostrProtocol.kt

@@ -73,14 +73,24 @@ object NostrProtocol {
                 }
             
             Log.v(TAG, "Successfully unwrapped gift wrap from: ${seal.pubkey.take(16)}...")
-            
+
+            if (seal.kind != NostrKind.SEAL || !seal.isValidSignature()) {
+                Log.w(TAG, "❌ Invalid NIP-17 seal signature")
+                return null
+            }
+
             // 2. Open the seal
             val rumor = openSeal(seal, recipientIdentity.privateKeyHex)
                 ?: run {
                     Log.w(TAG, "❌ Failed to open seal")
                     return null
                 }
-            
+
+            if (seal.pubkey != rumor.pubkey) {
+                Log.w(TAG, "❌ NIP-17 seal pubkey does not match rumor pubkey")
+                return null
+            }
+
             Log.v(TAG, "Successfully opened seal")
             
             Triple(rumor.content, rumor.pubkey, rumor.createdAt)
@@ -227,7 +237,7 @@ object NostrProtocol {
             content = encrypted
         )
         
-        // Sign with the ephemeral key
+        // NIP-17 requires the seal to be signed by the sender identity key.
         return seal.sign(senderPrivateKey)
     }
     

app/src/main/java/com/bitchat/android/ui/ChatViewModel.kt

@@ -938,6 +938,11 @@ class ChatViewModel(
                 store.clearAll()
             } catch (_: Exception) { }
 
+            try {
+                val locationManager = com.bitchat.android.geohash.LocationChannelManager.getInstance(getApplication())
+                locationManager.clearPersistedChannel()
+            } catch (_: Exception) { }
+
             geohashViewModel.panicReset()
         } catch (e: Exception) {
             Log.e(TAG, "Failed to reset Nostr/geohash: ${e.message}")