[Cryptography] Regulations of Tempest protections of buildings
Bill Frantz
frantz at pwpconsult.com
Mon Apr 10 21:40:54 EDT 2017
On 4/10/17 at 2:31 PM, iang at iang.org (iang) wrote:
>Like Ham radio operators yelling at you if you start using crypto...
In the US, and I suspect almost everywhere else, it is illegal
to attempt to hide the meaning of communications via ham radio.
(There's an exception for controlling a satellite.) All of the
codes used by hams (e.g. the Q codes) are published, the data
encoding techniques are also published, and cyphers aren't used.
Hams generally want to be seen by government regulators as being
good actors as a way of protecting the spectrum allocations they
have. Hence bristling when you start using crypt.
As an aside, I think we are safer if people with scanners can
understand police radio communication than if these
communications are encrypted, as is becoming more common.
As I read the regulations, crypto can be used for
authentication. There are a number of applications where this
would actually be useful, including limiting control of
repeaters to authorized people. In this application, replay
prevention is the biggest problem.
When I was working on the E communication protocol, the US
government was trying like mad to suppress the legal use of
crypto for secrecy. I looked at what it would take to yank the
secrecy while keeping the authentication, and it turned out to
be a hard problem. The tokens the E runtime passed between
machines to identify remote objects needed to be kept secret. I
think the problem could have been solved, but I am very glad I
didn't have to solve it.
Cheers - Bill
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