[Cryptography] nuclear arming codes

[Peter Gutmann]

Peter Fairbrother <zenadsl6186 at zen.co.uk> writes:

>One technique I'm told is still in use is to affix glitter in random patterns
>in clear epoxy to missile and/or warhead parts, then shine lights on it from
>variable positions and compare the return sparkle images to a known set for
>that patch. Very hard to forge.

This was developed over a number of years in the 1980s, read using an embedded
x86 system programming in Pascal (an impressive piece of image processing for
the time).  It was just getting ready for deployment when the Soviet Union
collapsed, and was replaced by a mechanism that was described to me as "magic
marker on the side of the missile".  There were some (hard-to-find) papers
published on it after the project was canned, it was basically PUFs two
decades before they were called PUFs.

Peter.