No connected system is ever going to be both useful and  absolutely impenetrable , and no single defence of that system aside can guarantee impenetrability. It therefore makes sense to protect it proportionately to the level of risk involved if it were to be compromised, and that means applying multiple levels of  security  so that if one level fails, others are standing guard  – a “defence in depth”  approach .   Secure application code represents just one component  in  such a strategy.     

Across the sectors, the  rise of connectivity and the need to  systematically implement correspondingly secure systems has been a challenge.  The established approach of developing and refining process  standards over many years that has proved so  successful  in achieving functional safety  is only partially  suited to the world of  security , not least because of the ever-changing nature of security threats . It is much easier to protect the world from a system, than it is to protect a system from the world.  

T h at said, the  wise words offered by the likes of  DefStan 05-138, NIST SP 800-171 and ISO/IEC 27001:2013  are potentially applicable to  securing the systems of digital battlefield.  In particular, the  g lobally  renowned  aerospace standards of the ‘DO’ family  include  DO-326A  which might lend itself admirably to the circumstances, give n   its  consideration of the implications of  security  for certification.