contrib: add sign.sh

contrib/sign.sh

+#!/bin/sh
+
+if [ $# -eq 0 -o "-h" = "$1" -o "-help" = "$1" -o "--help" = "$1" ]; then
+	cat <<EOHELP
+Usage: $0 <secret> <manifest>
+EOHELP
+	exit 1
+fi
+ 
+SECRET=$1
+ 
+manifest=$2
+upper=$(mktemp)
+lower=$(mktemp)
+ 
+awk "BEGIN    { sep=0 }
+     /^---\$/ { sep=1; next }
+              { if(sep==0) print > \"$upper\";
+                else       print > \"$lower\"}" \
+    $manifest
+ 
+ecdsasign $upper < $SECRET >> $lower
+ 
+cat  $upper  > $manifest
+echo ---    >> $manifest
+cat  $lower >> $manifest
+ 
+rm -f $upper $lower