This subtitle has been carefully sanitized for your convenience and protection.
R
eaders of this blog may recall that in the Fall of 2005, my graduate
students (Micah Sherr, Eric Cronin, and Sandy Clark) and I discovered
that the telephone wiretap technology commonly used by law enforcement
agencies can be misled or disabled altogether simply by sending various low-level audio signals on the target's line [link our full pdf paper here]. Fortunately, certain newer tapping systems, based on the 1994 CALEA regulations,
have the potential to neutralize these vulnerabilities, depending on
how they are configured. Shortly after we informed the FBI about our
findings, an FBI spokesperson reassured the New York Times that the problem was now largely fixed and affects less than 10 percent of taps [link].
<snip>
Are you a Stooge, a Dimwit, or a Savant?
When I published Safecracking for the Computer Scientist [pdf] a few years ago,
I worried that I might be alone in harboring
a serious interest in the cryptologic aspects of physical security.
Yesterday I was delighted to discover that I had been wrong. It turns out that more than
ten years before I wrote up my safecracking survey, a detailed
analysis of the keyspaces of mechanical safe locks had already been
written, suggesting a simple and practical dictionary attack of which I was completely
unaware. But I have an excuse for my ignorance: the study was published
in secret, in Cryptologic Quarterly, a classified technical
journal of the US National Security Agency.
From the turtles-all-the-way-down department.
Computer security depends ultimately on the security of the computer --
it's an indisputable tautology so self-evident that it seems almost
insulting to point it out. Yet what may be obvious in the abstract is
sometimes dangerously under-appreciated in practice. Security people
come predominantly from software-centric backgrounds and we're often
predisposed to relentlessly scrutinize the things we understand best
while quietly assuming away everything else. But attackers, sadly, are
under no obligation to play to our analytical preferences. Several
recent research results make an eloquent and persuasive case that a
much broader view of security is needed. A bit of simple hardware
trickery, we're now reminded, can subvert a system right out from under
even the most carefully vetted and protected software.
Earlier this year, Princeton graduate student Alex Halderman and seven of his colleagues discovered practical
techniques for extracting the contents of DRAM memory, including cryptographic keys, after a computer has been turned off [link].
This means, among other worries, that if someone -- be it a casual
thief or a foreign intelligence agent -- snatches your laptop, the fact
that it had been "safely" powered down may be insufficient to protect
your passwords and disk encryption keys. And the techniques are simple
and non-destructive, involving little more than access to the memory
chips and some canned-air coolant.
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