From d79ba4d77693dd6a459f545dc5f900f5ab57825b Mon Sep 17 00:00:00 2001
From: Rahul Tank <rahul.tank@espressif.com>
Date: Tue, 14 Sep 2021 09:28:59 +0530
Subject: [PATCH] Nimble/host: Compare only x component of public key before
 pairing

Update fix of MITM vulnerability during public key exchange in secure connection
---
 nimble/host/src/ble_sm_sc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/nimble/host/src/ble_sm_sc.c b/nimble/host/src/ble_sm_sc.c
index 562f33b51..ace49e34a 100644
--- a/nimble/host/src/ble_sm_sc.c
+++ b/nimble/host/src/ble_sm_sc.c
@@ -612,6 +612,14 @@ ble_sm_sc_public_key_rx(uint16_t conn_handle, struct os_mbuf **om,
 
     cmd = (struct ble_sm_public_key *)(*om)->om_data;
 
+    /* Check if the X component of peer public key is same as X component of our generated public key.
+     * Return fail if they match. */
+    if (memcmp(cmd, ble_sm_sc_pub_key, 32) == 0) {
+        res->enc_cb = 1;
+        res->sm_err = BLE_SM_ERR_AUTHREQ;
+        return;
+    }
+
     ble_hs_lock();
     proc = ble_sm_proc_find(conn_handle, BLE_SM_PROC_STATE_PUBLIC_KEY, -1,
                             NULL);