diff --git a/target/linux/ramips/image/mt7621.mk b/target/linux/ramips/image/mt7621.mk
index 8fba65e0ec6..d2ba00f85ad 100644
--- a/target/linux/ramips/image/mt7621.mk
+++ b/target/linux/ramips/image/mt7621.mk
@@ -120,8 +120,13 @@ define Build/haier-sim_wr1800k-factory
   mkdir -p "$@.tmp"
   mv "$@" "$@.tmp/UploadBrush-bin.img"
   $(MKHASH) md5 "$@.tmp/UploadBrush-bin.img" | head -c32 > "$@.tmp/check_MD5.txt"
-  $(TAR) -czf "$@.tmp.tgz" -C "$@.tmp" UploadBrush-bin.img check_MD5.txt
-  $(STAGING_DIR_HOST)/bin/openssl aes-256-cbc -e -salt -in "$@.tmp.tgz" -out "$@" -k QiLunSmartWL
+  $(TAR) -C "$@.tmp" \
+	--numeric-owner --owner=0 --group=0 --mode=go-w --sort=name \
+	$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
+	-cf - UploadBrush-bin.img check_MD5.txt | gzip -n -9 > "$@.tmp.tgz"
+  $(STAGING_DIR_HOST)/bin/openssl aes-256-cbc -e \
+	-S 4f70656e57727421 \
+	-in "$@.tmp.tgz" -out "$@" -k QiLunSmartWL
   printf %32s $(DEVICE_MODEL) >> "$@"
   rm -rf "$@.tmp" "$@.tmp.tgz"
 endef