fix: SecretTree skipped keys, sentKeys cleanup, markAsRead, key zeroing

- H11: Cache skipped message keys in SecretTree for out-of-order decryption
- L1: Prune sentKeys map when exceeding 10000 entries
- L2: Prune consumed generations below current minimum
- H17: Call markAsRead when chat view is opened
- Key zeroing: Zero old private keys in KeyPackageRotationManager

https://claude.ai/code/session_018gVkmmYgMFtBH7G31pCk9N

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/marmotGroup/MarmotGroupChatView.kt

@@ -31,6 +31,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextFieldDefaults
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
@@ -74,6 +75,15 @@ fun MarmotGroupChatView(
 
     WatchLifecycleAndUpdateModel(feedViewModel)
 
+    val chatroom = remember(nostrGroupId) {
+        accountViewModel.account.marmotGroupList.getOrCreateGroup(nostrGroupId)
+    }
+
+    DisposableEffect(nostrGroupId) {
+        chatroom.markAsRead()
+        onDispose { }
+    }
+
     Column(Modifier.fillMaxHeight()) {
         Column(
             modifier =

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mip00KeyPackages/KeyPackageRotationManager.kt

@@ -63,7 +63,7 @@ class KeyPackageRotationManager {
      * @param dTagSlot the d-tag slot for addressable replacement
      * @return a [KeyPackageBundle] containing the KeyPackage and all private keys
      */
-    fun generateKeyPackage(
+    suspend fun generateKeyPackage(
         identity: ByteArray,
         dTagSlot: String = KeyPackageUtils.PRIMARY_SLOT,
     ): KeyPackageBundle {
@@ -96,7 +96,9 @@ class KeyPackageRotationManager {
             )
 
         val bundle = KeyPackageBundle(keyPackage, initKp.privateKey, encKp.privateKey, sigKp.privateKey)
-        activeBundles[dTagSlot] = bundle
+        mutex.withLock {
+            activeBundles[dTagSlot] = bundle
+        }
         return bundle
     }
 
@@ -120,24 +122,26 @@ class KeyPackageRotationManager {
      * The slot will be included in [pendingRotationSlots] and should be
      * rotated by the caller.
      */
-    fun markConsumed(dTagSlot: String) {
-        activeBundles.remove(dTagSlot)
-        pendingRotations.add(dTagSlot)
-    }
+    suspend fun markConsumed(dTagSlot: String) =
+        mutex.withLock {
+            activeBundles.remove(dTagSlot)
+            pendingRotations.add(dTagSlot)
+        }
 
     /**
      * Mark a slot as consumed by looking up the KeyPackage reference.
      */
-    fun markConsumedByRef(keyPackageRef: ByteArray) {
-        val entry =
-            activeBundles.entries.find { (_, bundle) ->
-                bundle.keyPackage.reference().contentEquals(keyPackageRef)
+    suspend fun markConsumedByRef(keyPackageRef: ByteArray) =
+        mutex.withLock {
+            val entry =
+                activeBundles.entries.find { (_, bundle) ->
+                    bundle.keyPackage.reference().contentEquals(keyPackageRef)
+                }
+            if (entry != null) {
+                activeBundles.remove(entry.key)
+                pendingRotations.add(entry.key)
             }
-        if (entry != null) {
-            activeBundles.remove(entry.key)
-            pendingRotations.add(entry.key)
         }
-    }
 
     /**
      * Get the d-tag slots that need rotation (KeyPackage was consumed).

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mip01Groups/MarmotGroupData.kt

@@ -22,8 +22,10 @@ package com.vitorpamplona.quartz.marmot.mip01Groups
 
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.marmot.mls.codec.TlsReader
+import com.vitorpamplona.quartz.marmot.mls.codec.TlsWriter
 import com.vitorpamplona.quartz.marmot.mls.tree.Extension
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.core.hexToByteArray
 import com.vitorpamplona.quartz.nip01Core.core.toHexKey
 
 /**

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mls/group/MlsGroup.kt

@@ -491,6 +491,15 @@ class MlsGroup private constructor(
      * Encrypt an application message as a PrivateMessage.
      */
     fun encrypt(plaintext: ByteArray): ByteArray {
+        // Trim sentKeys if it grows too large
+        if (sentKeys.size > MAX_SENT_KEYS) {
+            val sortedKeys = sentKeys.keys.sorted()
+            val toRemove = sortedKeys.take(sentKeys.size - MAX_SENT_KEYS)
+            for (key in toRemove) {
+                sentKeys.remove(key)
+            }
+        }
+
         val kng = secretTree.nextApplicationKeyNonce(myLeafIndex)
         sentKeys[kng.generation] = kng
         val ciphertext = MlsCryptoProvider.aeadEncrypt(kng.key, kng.nonce, ByteArray(0), plaintext)
@@ -1190,6 +1199,7 @@ class MlsGroup private constructor(
     }
 
     companion object {
+        private const val MAX_SENT_KEYS = 10_000
         private const val RATCHET_TREE_EXTENSION_TYPE = 0x0001
         private const val REQUIRED_CAPABILITIES_EXTENSION_TYPE = 0x0002
         private const val EXTERNAL_PUB_EXTENSION_TYPE = 0x0003

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mls/schedule/SecretTree.kt

@@ -56,6 +56,19 @@ class SecretTree(
     /** Consumed (sender, generation) pairs for replay detection (RFC 9420 Section 9.1) */
     private val consumedGenerations = mutableMapOf<Int, MutableSet<Int>>()
 
+    /**
+     * Cache of key/nonce pairs for skipped generations.
+     * Key: (leafIndex, generation) -> derived KeyNonceGeneration.
+     * When fast-forwarding a ratchet, intermediate generations are saved here
+     * so that out-of-order messages arriving later can still be decrypted.
+     */
+    private val skippedKeys = mutableMapOf<Pair<Int, Int>, KeyNonceGeneration>()
+
+    /** Maximum number of skipped key entries to retain (prevents unbounded memory growth). */
+    private companion object {
+        const val MAX_SKIPPED_KEYS = 1000
+    }
+
     init {
         // Seed the root
         treeSecrets[BinaryTree.root(leafCount)] = encryptionSecret
@@ -111,11 +124,27 @@ class SecretTree(
     /**
      * Get the (key, nonce) for a specific generation, consuming secrets up to that point.
      * Used when decrypting an out-of-order message.
+     *
+     * When fast-forwarding past intermediate generations, their key/nonce pairs
+     * are cached in [skippedKeys] so that out-of-order messages arriving later
+     * can still be decrypted.
      */
     fun applicationKeyNonceForGeneration(
         leafIndex: Int,
         generation: Int,
     ): KeyNonceGeneration {
+        // Check skipped keys cache first (out-of-order message for a previously skipped generation)
+        val cachedKey = skippedKeys.remove(Pair(leafIndex, generation))
+        if (cachedKey != null) {
+            // Still mark as consumed for replay detection
+            val senderConsumed = consumedGenerations.getOrPut(leafIndex) { mutableSetOf() }
+            require(generation !in senderConsumed) {
+                "Replay detected: generation $generation from sender $leafIndex already consumed"
+            }
+            senderConsumed.add(generation)
+            return cachedKey
+        }
+
         val state = getOrInitSender(leafIndex)
 
         require(generation >= state.applicationGeneration) {
@@ -129,10 +158,16 @@ class SecretTree(
         }
         senderConsumed.add(generation)
 
-        // Fast-forward the ratchet
+        // Fast-forward the ratchet, caching intermediate key/nonce pairs
         var secret = state.applicationSecret
         var gen = state.applicationGeneration
         while (gen < generation) {
+            // Save the intermediate generation's key/nonce for later out-of-order retrieval
+            val intermediateKng = deriveKeyNonce(secret, gen)
+            val cacheKey = Pair(leafIndex, gen)
+            if (skippedKeys.size < MAX_SKIPPED_KEYS) {
+                skippedKeys[cacheKey] = intermediateKng
+            }
             secret = MlsCryptoProvider.expandWithLabel(secret, "secret", generationContext(gen), MlsCryptoProvider.HASH_OUTPUT_LENGTH)
             gen++
         }