shellcheck: zero_length_keys.sh issues

In zero_length_keys.sh line 22:
if [ $# -eq 0 ] || [ ! -f ${1} ] || [ ! -x ${1} ]; then
                          ^-- SC2086: Double quote to prevent globbing and word splitting.
                                           ^-- SC2086: Double quote to prevent globbing and word splitting.


In zero_length_keys.sh line 34:
DATA_DIR=`mktemp -d -t tor_zero_length_keys.XXXXXX`
         ^-- SC2006: Use $(..) instead of legacy `..`.


In zero_length_keys.sh line 43:
trap "rm -rf '$DATA_DIR'" 0
              ^-- SC2064: Use single quotes, otherwise this expands now rather than when signalled.