If the hardware's physical security was compromised the sensitive data it contained should remain impenetrable even to government instigated attacks. The facility needs to be publicly available online 24 hours - 7 days a weeks across insecure public networks, but still not hackable. Any idea of building then administering some trusted public-key encryption scheme for such user volume and profile was considered impractical. As it could be up-to ten year between when data retrieval maybe required. Other encryption schemes where dismissed by the sufficient strength to be unbreakable, while technology was easily exportable dilemma.
Traditional cryptography is weakest when the same cipher is used identically on multiple occasion.
The shorter the key length the more effective are standard statistical frequency attacks. Hardwired solutions are vulnerable to reverse engineering when attackers can monitor devices known plaintext inputs and the output cryptogram. But most importantly all the above share common assumptions about how the concealment task should be tackled. Therefore the most promising path to a new solution space is through breaking the accepted conventions, particularly by corrupting ubderlying assumptions. Another promising path to alternative solution space is by investigating recent developments outside of the traditional cryptography mathematics nexus.