Gaming Security by Obscurity
Shannon sought security against the attacker with unlimited computational powers: if information source conveys some information, then Shannon's attacker will surely extract that information. Diffie and Hellman refined Shannon's attacker model by taking into account the fact that the real attackers are computationally limited. This idea became one of the greatest new paradigms in computer science, and led to modern cryptography. Shannon also sought security against the attacker with unlimited logical and observational powers, expressed through the maxim that "The enemy knows the system". This view is still endorsed in cryptography.