--- fit_tools/fit-add-avm-header.sh
+++ fit_tools/fit-add-avm-header.sh
@@ -30,6 +30,7 @@
 # This script takes a FIT image built with U-boot's 'mkimage' command and adds a header using AVM's   #
 # extension format.                                                                                   #
 # The data part, which looks like a cryptographic signature to me, will be filled with zeros.         #
+### [cuma] optional copy this data part from given source file [cuma]                               ###
 #                                                                                                     #
 #######################################################################################################
 #                                                                                                     #
@@ -149,6 +150,7 @@
 		printf -- "Usage: %s [ options ] <standard-fit-image>\n\n" "$0"
 		printf -- "Options:\n\n"
 		printf -- "-d or --debug - show some extra info on STDERR\n"
+		printf -- "-k or --key FILE - extract 512bit key from FILE\n"
 		printf -- "\n"
 		exec 1>&2
 	}
@@ -159,12 +161,20 @@
 	fdt32_size=4
 
 	dbg=0
+	key=
 	while [ "$(expr "$1" : "\(.\).*")" = "-" ]; do
 		[ "$1" = "--" ] && shift && break
 
 		if [ "$1" = "-d" ] || [ "$1" = "--debug" ]; then
 			dbg=1
 			shift
+		elif [ "$1" = "-k" ] || [ "$1" = "--key" ]; then
+			shift
+			key=$1
+			! [ -n "$key" ] && printf -- "A file is mandatory for key parameter\a\n" 1>&2 && exit 1
+			! [ -e "$key" ] && printf -- "File not found: %s\a\n" "$key" 1>&2 && exit 1
+			! [ -s "$key" ] && printf -- "File is empty: %s\a\n" "$key" 1>&2 && exit 1
+			shift
 		elif [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
 			usage
 			exit 0
@@ -215,6 +225,16 @@
 	fi
 
 	# TODO: further investigations to find the algorithm used to fill this area
+	# UNTIL THEN: just copy from given source file, in case its something magic
+if [ "$key" != "" ]; then
+	debug "Copying so called signature area ..."
+	if dd if="$key" bs=1 skip=8 count=64 iflag=skip_bytes,count_bytes 2>"$null"; then
+		result 0 " OK"
+	else
+		result 1 " failed"
+		exit 1
+	fi
+else
 	debug "Writing zeros to (assumed) signature area ..."
 	if dd if="$zeros" bs=64 count=1 2>"$null"; then
 		result 0 " OK"
@@ -222,6 +242,7 @@
 		result 1 " failed"
 		exit 1
 	fi
+fi
 
 	debug "Copying standard FIT data ..."
 	if dd if="$img" bs=$(( 1024 * 1024 )) 2>"$null"; then