Open design would seem to favor the attacker, because it certainly opens the implementation and perhaps also the design for the attacker to study. Justify that open design overrides this seeming advantage and actually leads to solid security

What will be an ideal response?

Open
design
allows
for
much
closer
inspection
of
the
security
system—more
awareness
of
the
security
practices
in
place
is
more
likely
to
reveal
vulnerabilities
to
enable
resolving
those
vulnerabilities
rather
than
their
exploitation.
Obscurity
is
an
insufficient
security
mechanism,
open
design
allows
a
more
thorough
inspection,
and
knowing
that
a
design
will
be
open
should
make
designers
more
careful.