This blog item appears to have been plagiarized from Steve Bellovin's page:<p><a href="https://www.cs.columbia.edu/~smb/nsam-160/pal.html" rel="nofollow">https://www.cs.columbia.edu/~smb/nsam-160/pal.html</a>
What does the PAL do when it detects unauthorized tampering?<p>For fission weapons, isn't the most critical part the core? One design criterion for a PAL is to prevent scattering of fissile material, so the core remains intact, right? How hard can it be for a rogue state or group to create a new bomb given that the fissile core is the most valuable part of a fission bomb?<p>For a fusion bomb, I guess the PAL would damage the aerogel ("fogbank") among other things. That would take some advanced knowledge to redesign, but whoever has the weapon would still have the fissile material from the first stage even if they can't get the fusion part of humpty dumpty back together again.<p>The original fission bombs were designed in the 1940s with slide rules. It seems to me that PALs do a better job of protecting against unauthorized fusion detonations than of protecting against unauthorized re-engineering of the bombs into fission or radiological versions using the fission core.
PALs and the START tamper sensors are some of the most amazing implementations of tamper resistance in the history of mankind. They are what got me interested in the stuff in the mid 1990s, followed by the weirdness of DRM schemes for anti piracy.