> Cryptography can be supplemented by
> plain old detective work.
Possibly the only disadvantage of strong cryptography is that it will make
"plain old detective work" cheaper than breaking your encrypted
messages...
> Why is that the point? There is nothing casual about this. Recognizing
> the various kinds of pseudorandom sequences produced by various
> encryption schemes is not easy;
But that's not what you're trying to do. The strongly encrypted data would
be *superencrypted* with the RNG output. So you're not even looking for
data from a different sequence, but encrypted data that has been XOR-ed
with the RNG output. That's an even harder task. I don't think that you
can do it without cracking the RNG, otherwise you'll get false positives
from compressed data.
[Suppose the NSA has loads of money]
> Then a lot of things become possible.
Well, let's try a thought-experiment... Suppose you convert every atom of
the Earth into DNA (converting iron into other elements as appropriate)
and use it as a DNA computer (the fastest method anyone I know has
suggested to crack conventional ciphers), and that a DNA structure of
1,000,000 atoms can try ten possible keys or RNG seeds every nanosecond.
If my rough calculations are correct, your DNA computer will only take
about 10^32 years to break a 3-key triple-DES message or determine the
seed of a strong 192-bit PRNG.
However, if we were only using 64-bit PRNGs and changing the key once per
second then with those parameters you'd potentially need only 1.5 kg of
DNA to read all Internet traffic (of course the real amount would be
rather larger but not impossible), so you may be correct for weak PRNGs --
that would include ordinary 56-bit DES. Ouch.
> If there is a standard covering
> that most people use, and somebody uses a different, more opaque
> covering, that person has called attention to himself.
I disagree. It's more like everyone paints their windows black to keep
their business private, but some people also have a further layer of
opaque and bulletproof windows inside just in case someone breaks the
outer windows.
Mark
|-----------------------------------------------------------------------|
|Mark Grant M.A., U.L.C. EMAIL: mark@unicorn.com |
|WWW: http://www.c2.org/~mark MAILBOT: bot@unicorn.com |
|-----------------------------------------------------------------------|