Provided with equipment, space and operating expenses by the National Security Agency (NSA), the museum is immediately next to NSA’s headquarters in Ft Meade Maryland. It contains many very nice examples of systems, starting with completely manual systems and progressing through mechanical, electromechanical and then some very heavy duty computer-based systems, both for the transfer of secret messages, and also for breaking open those secret communications.
All of the examples in the museum represented coding systems that were actually broken, sometimes only after considerable effort, or systems that, using modern methods including massively parallel computing systems, would have eventually been broken.
Almost all such systems, given enough time and compute power, can be broken.
But not one-time pads. They are impervious. If generated and then used correctly, they literally cannot be broken.
But they’re not in the museum.
Why would the NSA leave them out, I wonder?