PGP Signature and Melissa Stuff

[Steve Lamb]

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On Tue, 27 Apr 1999 16:13:25 -0500, John Thompson wrote:

>I think this is the "security through obscurity" approach.  As long as
>only a few people are using encryption only for specific purposes, anybody
>monitoring such use will be able to target those people for cracking their
>secret keys.  OTOH, if everybody used encryption regardless of the message
>content, then those people whose encrypted messages carry "interesting"
>information will be harder to target for cracking since there's no way of
>distinguishing an "interesting" message from an uninteresting one without
>decrypting each and every message.  Which puts it in the category of "too
>much work."

    I just wanted to add that this is a good use of security through
obscurity.  It is not depending on obsucirty for all of the security, just
using it to add to the security already present.

    There are three models.  No encryption, some encryption, all encryption.

No Encryption.

    This method relies on security through obscurity.  The theory is that
there is so much information out there that it would be impossible, or, at
the very least, highly improbable that someone can pick your messages out of
the noise.  Patently untrue.  As a former postmaster for a local ISP, rest
assured, it is easier than most people think for people to isolate and obtain
messages.


Some Encryption.

    IE, only the "important messages" are encrypted.  This is a little better
than before except that any messages that are encrypted in a stream of
unencrypted messages is screaming "CRACK ME, I HAVE IMPORTANT INFORMATION!!!
HERE I AM!!!"  Granted, there is no easy way to crack anything 56bit
encryption and above that is publicly known.  Key word, publicly.  Projects
like distributed.net are proving that the lower bit counts are entirely too
easy to break with the brute force method.


All Encryption

    This combines the two methods above.  By encrypting all messages none of
them stand out of the crowd.  Furthermore, if what I read on this list
recently is correct, the encrypted messages are also compressed at a fairly
high compression ratio.  That means the difference between a "small" message
and a "large" message is diminished.  So now a potential bad guy is faced
with a stream of encrypted data which removes one flag, as well as the
individual messages being closer in size, so going for the "larger" message
does not mean much either.  Once s/he's chosen one and cracks it (taking
hours, weeks, months) and finds out it is, "Mom, thanks for the donuts, your
son" I bet they would find that rather discouraging.


    The point is that by encrypting everything regardless of importance one
removes a potential flag for which message to target for a brute-force or
other cryptological attack against those messages you *DO* want to remain
secure.

    To that end, that is why I sign all my messages currently.  I do it to
get people used to the idea of PGP, electronic signatures and encryption.
The importance, or lack there of, of the message is irrelevent to me.

- --
         Steve C. Lamb         | I'm your priest, I'm your shrink, I'm your
         ICQ: 5107343          | main connection to the switchboard of souls.
- -------------------------------+---------------------------------------------

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