perf(e2ee): cache optimization

- shared secret key cache
- remove uncommitted messages from the cache

app/src/main/kotlin/me/rhunk/snapenhance/e2ee/E2EEImplementation.kt

@@ -3,6 +3,7 @@ package me.rhunk.snapenhance.e2ee
 import me.rhunk.snapenhance.RemoteSideContext
 import me.rhunk.snapenhance.bridge.e2ee.E2eeInterface
 import me.rhunk.snapenhance.bridge.e2ee.EncryptionResult
+import me.rhunk.snapenhance.core.util.EvictingMap
 import org.bouncycastle.pqc.crypto.crystals.kyber.*
 import java.io.File
 import java.security.MessageDigest
@@ -23,25 +24,33 @@ class E2EEImplementation (
     }}
     private val pairingFolder by lazy { File(context.androidContext.cacheDir, "e2ee-pairing").also {
         if (!it.exists()) it.mkdirs()
+        else {
+            it.deleteRecursively()
+            it.mkdirs()
+        }
     } }
 
+    private val sharedSecretKeyCache = EvictingMap<String, ByteArray?>(100)
+
     fun storeSharedSecretKey(friendId: String, key: ByteArray) {
         File(e2eeFolder, "$friendId.key").writeBytes(key)
+        sharedSecretKeyCache[friendId] = key
     }
 
     fun getSharedSecretKey(friendId: String): ByteArray? {
-        return runCatching {
-            File(e2eeFolder, "$friendId.key").readBytes()
-        }.onFailure {
-            context.log.error("Failed to read shared secret key", it)
-        }.getOrNull()
+        return sharedSecretKeyCache.getOrPut(friendId) {
+            runCatching {
+                File(e2eeFolder, "$friendId.key").readBytes()
+            }.onFailure {
+                context.log.error("Failed to read shared secret key", it)
+            }.getOrNull()
+        }
     }
 
     fun deleteSharedSecretKey(friendId: String) {
         File(e2eeFolder, "$friendId.key").delete()
     }
 
-
     override fun createKeyExchange(friendId: String): ByteArray? {
         val keyPairGenerator = KyberKeyPairGenerator()
         keyPairGenerator.init(
@@ -117,12 +126,7 @@ class E2EEImplementation (
     }
 
     override fun getSecretFingerprint(friendId: String): String? {
-        val sharedSecretKey = runCatching {
-            File(e2eeFolder, "$friendId.key").readBytes()
-        }.onFailure {
-            context.log.error("Failed to read shared secret key", it)
-            return null
-        }.getOrThrow()
+        val sharedSecretKey = getSharedSecretKey(friendId) ?: return null
 
         return MessageDigest.getInstance("SHA-256")
             .digest(sharedSecretKey)
@@ -132,11 +136,7 @@ class E2EEImplementation (
     }
 
     override fun encryptMessage(friendId: String, message: ByteArray): EncryptionResult? {
-        val encryptionKey = runCatching {
-            File(e2eeFolder, "$friendId.key").readBytes()
-        }.onFailure {
-            context.log.error("Failed to read shared secret key", it)
-        }.getOrNull()
+        val encryptionKey = getSharedSecretKey(friendId) ?: return null
 
         return runCatching {
             val iv = ByteArray(16).apply { secureRandom.nextBytes(this) }
@@ -152,12 +152,7 @@ class E2EEImplementation (
     }
 
     override fun decryptMessage(friendId: String, message: ByteArray, iv: ByteArray): ByteArray? {
-        val encryptionKey = runCatching {
-            File(e2eeFolder, "$friendId.key").readBytes()
-        }.onFailure {
-            context.log.error("Failed to read shared secret key", it)
-            return null
-        }.getOrNull()
+        val encryptionKey = getSharedSecretKey(friendId) ?: return null
 
         return runCatching {
             val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")

core/src/main/kotlin/me/rhunk/snapenhance/core/features/impl/experiments/EndToEndEncryption.kt

@@ -16,6 +16,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import me.rhunk.snapenhance.common.data.ContentType
+import me.rhunk.snapenhance.common.data.MessageState
 import me.rhunk.snapenhance.common.data.MessagingRuleType
 import me.rhunk.snapenhance.common.data.RuleState
 import me.rhunk.snapenhance.common.util.protobuf.ProtoEditor
@@ -312,7 +313,7 @@ class EndToEndEncryption : MessagingRuleFeature(
             if (messageTypeId == ENCRYPTED_MESSAGE_ID) {
                 runCatching {
                     eachBuffer(2) {
-                        if (encryptedMessages.contains(clientMessageId)) return@eachBuffer
+                        if (decryptedMessageCache.containsKey(clientMessageId)) return@eachBuffer
 
                         val participantIdHash = getByteArray(1) ?: return@eachBuffer
                         val iv = getByteArray(2) ?: return@eachBuffer
@@ -373,10 +374,15 @@ class EndToEndEncryption : MessagingRuleFeature(
         return outputContentType to outputBuffer
     }
 
-    private fun messageHook(conversationId: String, messageId: Long, senderId: String, messageContent: MessageContent) {
+    private fun messageHook(conversationId: String, messageId: Long, senderId: String, messageContent: MessageContent, committed: Boolean) {
         val (contentType, buffer) = tryDecryptMessage(senderId, messageId, conversationId, messageContent.contentType ?: ContentType.CHAT, messageContent.content!!)
         messageContent.contentType = contentType
         messageContent.content = buffer
+        // remove messages currently being sent from the cache
+        if (!committed) {
+            decryptedMessageCache.remove(messageId)
+            encryptedMessages.remove(messageId)
+        }
     }
 
     override fun asyncInit() {
@@ -520,11 +526,13 @@ class EndToEndEncryption : MessagingRuleFeature(
         context.event.subscribe(BuildMessageEvent::class, priority = 0) { event ->
             val message = event.message
             val conversationId = message.messageDescriptor!!.conversationId.toString()
+            val isMessageCommitted = message.messageState == MessageState.COMMITTED
             messageHook(
                 conversationId = conversationId,
                 messageId = message.messageDescriptor!!.messageId!!,
                 senderId = message.senderId.toString(),
-                messageContent = message.messageContent!!
+                messageContent = message.messageContent!!,
+                committed = isMessageCommitted
             )
 
             message.messageContent!!.instanceNonNull()
@@ -535,7 +543,8 @@ class EndToEndEncryption : MessagingRuleFeature(
                     conversationId = conversationId,
                     messageId = quotedMessage.getObjectField("mMessageId")?.toString()?.toLong() ?: return@also,
                     senderId = SnapUUID(quotedMessage.getObjectField("mSenderId")).toString(),
-                    messageContent = MessageContent(quotedMessage)
+                    messageContent = MessageContent(quotedMessage),
+                    committed = isMessageCommitted
                 )
             }
         }