Precise timing -- that's the key to my idea for a highly effective PAL. First, design the weapon to make the firing sequence as inherently complex and critical as possible. Vary the chemical composition and detonation velocities of the various pieces of high explosive so they have to be detonated non-simultaneously. Then store all of the required timing data in encrypted form in the weapon's memory. Better yet, encrypt everything (program and data) except for a small bootstrap that accepts an external key and decrypts everything for firing. Include this decryption key in the "nuclear weapons release" message from the "National Command Authority"
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