Dean Anderson wrote:
Then using the IETF list as an example, you would need the entire list of
recipients and their public keys, and you would need to send a message
either directly to each of them, one by one, or send a single message with
a session key for each recipient (thousands). This isn't going to work.
Let's not mix apples with speedboats. These are some options with the
proposal:
#1: no encryption is used either way, the list address is in a whitelist
for each recipient.
#2: each recipient can only send encrypted msgs (possibly, also
signed) to the list, with the list's key, for distribution. The listserver
verifies and resends the messages in plain text, where #1 applies for
each recipient.
#3: the list receives messages as in #2 but the listserver sends the
msgs as encrypted mail to each recipient, with each recipient's key.
IETF.ORG, possibly, should be #1. No problem in using postcards
here. However, to help prevent spam, IETF.ORG can use #2.
Second, even if the above weren't a problem, one still has the problem
that a virus infected user will still be sending messages, just like
everyone else.
Again, his would not work well with the proposal, due to the encryption
being per message. And the hijacked user would tend to notice any heavy
usage.
You can't make it more expensive without shooting yourself in the foot.
In information theory-speak, you can't prevent a covert channel** unless
you have no channel at all.
By the addition of a correction channel (Shannon's 10th theorem),
a covert channel can be detected with a probability as close to 100%
as I wish.
Covert-channel detection is a whack-a-mole game.
Not really. It can be modeled, it can be improved.
Putting it in different terms, how can the government make sure those
"government use only" stamped envelopes are only used for government
business?
Easy. By applying Shannon's 10th theorem. Sample enough mail at
distribution centers (going back to the source, which is possible
even without a legal mandate to open the envelopes) and bar the
culprits from sending govt. mail until the probability that any
mail is incorrectly using govt. envelopes is a close to zero as desired.
There is no scheme in which the rules can't be broken by someone intent on
breaking them.
This may sound good but is incorrect. Systems can be designed
such that a set of properties remain effective if most or even
all parts of the system fail (for whatever reason, including
attacks).
The only path is to detect them, and prosecute them.
There is no world law, no unified way to prosecute. Even
venue is hard to guarantee (allowing you to prosecute
the culprit).
In
the case of spam, detection is easy, but not automatic. Prosecution is
now possible. Its still a whack-a-mole game. It won't end unless you can
get past the virus infection to the virus operator, and hopefully, there
aren't really too many virus operators. Of course, we aren't stopping
spam either in a very real sense, but rather abusers who are annoying and
mailbombing people. But by my count of my inbox, if you stop those
people, I can certainly handle the rest which amounts to maybe 1% of my
current junk mail.
When you outlaw spam, only the outlaws spam. So what? The
problem still remains, even if you call them outlaws. Also,
users should not have to sue spammers, or have any other burden,
in order to protect the users' resources. Imagine if I would
have to manage 300 lawsuits a day (the average spam rate that
my system cannot automatically detect as spam)?