[FoRK] Crypto protocol for only good news?
Dave Long <
dave.long at bluewin.ch
> on >
Fri Aug 18 15:53:13 PDT 2006
> First, to sidestep the geopolitical issues of gender selection, I'll
> use a new example: you've taped the big game, and you don't want your
> friend to tell you who won before you've had a chance to watch it...
There's a square root in keeping covert channels obscure, so they're
more efficient for relatively infrequent events (like births) than for
relatively frequent events (like big games).*
For instance, for only 1 bit, the only possibilities are one-sided, and
the result is guaranteed to be as far from the expectation value as
possible. (The latter is no longer the case for two bits, but half of
the possibilities are still single-outcome)
Consider the LFSR, which looks very random locally yet globally very
:: :: ::
* the story goes that the allied group who were in charge of producing
bombing missions in hopes of provoking known-plaintext reports went to
some trouble to bury their signal in the noise, but they needn't have
bothered, as the german top brass didn't expect enigma was compromised.
(I was very disappointed to discover that the "humboldt squids" which
are said to fear Bruce Schneier are mere cephalopods, and not some kind
of weak-link woodpecker super tempest devices useful for
over-the-horizon clipping of a few quanta from the bits in your
network, at the cost of consuming both truly astronomical amounts of
LN2 and bushels of arcata's finest)
see also "physics & philosophical pyromania"
"audio subliminal channels"
or, for the math involved, "more random stuff"
all of which basically rotate around this article:
Haldane, "The Faking of Genetical Results", Eureka 27, 1941
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