From d3a516b05db38107883668b68317d474b3ad824b Mon Sep 17 00:00:00 2001
From: ariskotsomitopoulos <aris.kotsomitopoulos@gmail.com>
Date: Tue, 31 May 2022 11:26:26 +0300
Subject: [PATCH] Enhance key sharing to respect matrix configuration

---
 .../crypto/algorithms/megolm/MXMegolmDecryption.kt | 14 ++++++++++++--
 .../crypto/keysbackup/DefaultKeysBackupService.kt  | 12 +++++++++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmDecryption.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmDecryption.kt
index 53ff4b83ce..479c2654ed 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmDecryption.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmDecryption.kt
@@ -17,6 +17,7 @@
 package org.matrix.android.sdk.internal.crypto.algorithms.megolm
 
 import dagger.Lazy
+import org.matrix.android.sdk.api.MatrixConfiguration
 import org.matrix.android.sdk.api.logger.LoggerTag
 import org.matrix.android.sdk.api.session.crypto.MXCryptoError
 import org.matrix.android.sdk.api.session.crypto.NewSessionListener
@@ -41,6 +42,7 @@ internal class MXMegolmDecryption(
         private val olmDevice: MXOlmDevice,
         private val outgoingKeyRequestManager: OutgoingKeyRequestManager,
         private val cryptoStore: IMXCryptoStore,
+        private val matrixConfiguration: MatrixConfiguration,
         private val liveEventManager: Lazy<StreamEventsManager>
 ) : IMXDecrypting {
 
@@ -247,7 +249,7 @@ internal class MXMegolmDecryption(
                 forwardingCurve25519KeyChain = forwardingCurve25519KeyChain,
                 keysClaimed = keysClaimed,
                 exportFormat = exportFormat,
-                sharedHistory = roomKeyContent.sharedHistory ?: false
+                sharedHistory = roomKeyContent.getSharedKey()
         )
 
         when (addSessionResult) {
@@ -298,7 +300,15 @@ internal class MXMegolmDecryption(
     }
 
     /**
-     * Check if the some messages can be decrypted with a new session.
+     * Returns boolean shared key flag, if enabled with respect to matrix configuration
+     */
+    private fun RoomKeyContent.getSharedKey(): Boolean {
+        if (!matrixConfiguration.cryptoConfig.shouldShareKeyHistory) return false
+        return sharedHistory ?: false
+    }
+
+    /**
+     * Check if the some messages can be decrypted with a new session
      *
      * @param roomId the room id where the new Megolm session has been created for, may be null when importing from external sessions
      * @param senderKey the session sender key
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt
index 3514dae3f2..f8b00007bb 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt
@@ -27,6 +27,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.withContext
 import org.matrix.android.sdk.api.MatrixCallback
+import org.matrix.android.sdk.api.MatrixConfiguration
 import org.matrix.android.sdk.api.MatrixCoroutineDispatchers
 import org.matrix.android.sdk.api.auth.data.Credentials
 import org.matrix.android.sdk.api.crypto.MXCRYPTO_ALGORITHM_MEGOLM_BACKUP
@@ -120,6 +121,7 @@ internal class DefaultKeysBackupService @Inject constructor(
         private val updateKeysBackupVersionTask: UpdateKeysBackupVersionTask,
         // Task executor
         private val taskExecutor: TaskExecutor,
+        private val matrixConfiguration: MatrixConfiguration,
         private val inboundGroupSessionStore: InboundGroupSessionStore,
         private val coroutineDispatchers: MatrixCoroutineDispatchers,
         private val cryptoCoroutineScope: CoroutineScope
@@ -1457,7 +1459,7 @@ internal class DefaultKeysBackupService @Inject constructor(
                 },
                 forwardedCount = olmInboundGroupSessionWrapper.sessionData.forwardingCurve25519KeyChain.orEmpty().size,
                 isVerified = device?.isVerified == true,
-                sharedHistory = olmInboundGroupSessionWrapper.sessionData.sharedHistory,
+                sharedHistory = olmInboundGroupSessionWrapper.getSharedKey(),
                 sessionData = mapOf(
                         "ciphertext" to encryptedSessionBackupData.mCipherText,
                         "mac" to encryptedSessionBackupData.mMac,
@@ -1466,6 +1468,14 @@ internal class DefaultKeysBackupService @Inject constructor(
         )
     }
 
+    /**
+     * Returns boolean shared key flag, if enabled with respect to matrix configuration
+     */
+    private fun MXInboundMegolmSessionWrapper.getSharedKey(): Boolean {
+        if (!matrixConfiguration.cryptoConfig.shouldShareKeyHistory) return false
+        return sessionData.sharedHistory
+    }
+
     @VisibleForTesting
     @WorkerThread
     fun decryptKeyBackupData(keyBackupData: KeyBackupData, sessionId: String, roomId: String, decryption: OlmPkDecryption): MegolmSessionData? {