EncryptionKeyPair: only set a public key for 1-1 message case

libsession/src/main/java/org/session/libsession/messaging/messages/control/ClosedGroupControlMessage.kt

@@ -170,7 +170,7 @@ class ClosedGroupControlMessage() : ControlMessage() {
                 }
                 is Kind.EncryptionKeyPair -> {
                     closedGroupControlMessage.type = DataMessage.ClosedGroupControlMessage.Type.ENCRYPTION_KEY_PAIR
-                    closedGroupControlMessage.publicKey = kind.publicKey
+                    closedGroupControlMessage.publicKey = kind.publicKey ?: ByteString.EMPTY
                     closedGroupControlMessage.addAllWrappers(kind.wrappers.map { it.toProto() })
                 }
                 is Kind.NameChange -> {

libsession/src/main/java/org/session/libsession/messaging/sending_receiving/MessageSenderClosedGroup.kt

@@ -277,7 +277,9 @@ fun MessageSender.sendEncryptionKeyPair(groupPublicKey: String, newKeyPair: ECKe
         val ciphertext = MessageSenderEncryption.encryptWithSessionProtocol(plaintext, publicKey)
         ClosedGroupControlMessage.KeyPairWrapper(publicKey, ByteString.copyFrom(ciphertext))
     }
-    val kind = ClosedGroupControlMessage.Kind.EncryptionKeyPair(ByteString.copyFrom(Hex.fromStringCondensed(groupPublicKey)), wrappers)
+    // we only set public key of EncryptionKeyPair if we send the message to a one-on-one contact, otherwise if sent to a group it is set tu null as we use the one of the envelope
+    val kind = if (targetUser != null) ClosedGroupControlMessage.Kind.EncryptionKeyPair(ByteString.copyFrom(Hex.fromStringCondensed(groupPublicKey)), wrappers)
+        else ClosedGroupControlMessage.Kind.EncryptionKeyPair(null, wrappers)
     val sentTime = System.currentTimeMillis()
     val closedGroupControlMessage = ClosedGroupControlMessage(kind)
     closedGroupControlMessage.sentTimestamp = sentTime