From b3b50f6da8e44ade7baf9c00b0bee2d3bd41012c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Maciejo=C5=84czyk?=
 <32327281+lmaciejonczyk@users.noreply.github.com>
Date: Wed, 26 May 2021 23:03:48 +0200
Subject: [PATCH] [mac] always set Key Identifier for Transmit Security (#6678)

For multi-layer application, the radio requires from the upper layer
to provide information for security processing like Key Identifier,
in the Auxiliary Security Header according to IEEE802.15.4-2015.

This change matters for handling security processing by radio only.
---
 src/core/mac/sub_mac.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/core/mac/sub_mac.cpp b/src/core/mac/sub_mac.cpp
index 5b4f67e16..fea69f28b 100644
--- a/src/core/mac/sub_mac.cpp
+++ b/src/core/mac/sub_mac.cpp
@@ -328,10 +328,16 @@ void SubMac::ProcessTransmitSecurity(void)
     const ExtAddress *extAddress = nullptr;
     uint8_t           keyIdMode;
 
-    VerifyOrExit(ShouldHandleTransmitSecurity());
     VerifyOrExit(mTransmitFrame.GetSecurityEnabled());
     VerifyOrExit(!mTransmitFrame.IsSecurityProcessed());
 
+    if (!mTransmitFrame.IsARetransmission())
+    {
+        mTransmitFrame.SetKeyId(mKeyId);
+    }
+
+    VerifyOrExit(ShouldHandleTransmitSecurity());
+
     SuccessOrExit(mTransmitFrame.GetKeyIdMode(keyIdMode));
     VerifyOrExit(keyIdMode == Frame::kKeyIdMode1);
 
@@ -341,7 +347,6 @@ void SubMac::ProcessTransmitSecurity(void)
     {
         uint32_t frameCounter = GetFrameCounter();
 
-        mTransmitFrame.SetKeyId(mKeyId);
         mTransmitFrame.SetFrameCounter(frameCounter);
         UpdateFrameCounter(frameCounter + 1);
     }