This paper outlines simple changes that can be made to insert vulnerabilities into silicon that are invisible to current reverse-engineering techniques:
http://people.umass.edu/gbecker/BeckerChes13.pdf It uses Intel's random number generator as an example, detailing precisely how it can be weakened such that it has predictable output yet still appear perfectly random. This hack can be done by unobtrusive changes to the production masks in the chip fabs. One interesting note in the paper is that Intel has intentionally not included the normal JTAG-style debugging interfaces on the RNG that would allow you to spot this sort of tricker, ostensibly for security. The trade-off here is "attackers can't discreetly snoop on your RNG internals by physically connecting to pins on your CPU (though they can still snoop on everything else on your system including the RNG _output_)" vs "no one can validate the RNG behavior". This choice seems a little suspect. Secondly, the company Syphermedia does this sort of silicon-level trickery as a business: www.smi.tv/SMI_SypherMedia_Library_Intro.pdf Their primary customers appear to be companies making set-top boxes, but it would be interesting to investigate if they have any links to the NSA. -- Mathematics is the supreme nostalgia of our time. -- Liberationtech is public & archives are searchable on Google. Violations of list guidelines will get you moderated: https://mailman.stanford.edu/mailman/listinfo/liberationtech. Unsubscribe, change to digest, or change password by emailing moderator at compa...@stanford.edu.
