Re: Encrypt at which level?


PADLIPSKY@USC-ISI.ARPA
8 Apr 1986 16:07:17 EST


In response to your message sent Mon, 7 Apr 86 20:03:10 EST

Mike--
   Oh, dear, now you've gone and made me violate my vow not to work
up a sweat over ISOmetrics in public anymore....
   After several drafts that got too esoteric, I'll try to confine
myself to a couple of brief (possibly cryptic, but no pun is
intended) observations: In the first place, by Sutton's Law
it does make sense to "floogle" at L6; it's where the data are.
However, doing so would leave the lower L's headers unfloogled,
which I don't believe is consistent with what its proponents
seemed to think "end-to-end encryption" implied back in the bygone
days when I occasionally talked to them (informally, of course).
Let's pretend you meant "data encryption." (Or not, since it's
more or less a purist's point, along the lines of trying to
prevent anybody who has a different set of associations/connotations
with/for E-E E from being misled.)
   In the second place, putting floogling at L6 gives rise to all
sorts of questions I don't know the answers to about the nature
of the L7-L6 interface (which led me down a devious route I don't
want to go into here to a perception of still another architectural
inelegancy in the Seven Story Highrise). For a while, I thought
L6 floogling would require L6 to take inappropriate cognizance of
L7's distinction between control and data. Then I thought that
floogling didn't but being able to virtualize and devirtualize the
data did. Now from Steve's response I begin to wonder if I was
right in the first place (and I still think I'm part right in
the second place). Perhaps Steve will respond further if I just
assert that it's not obvious to me that you HAVE TO floogle
at L7, unless it has something to do with needing the control
information to be in the clear while the data are still encrypted
(or befloogled, as the case may be).
   Anyway, as of now I wish I hadn't asked...and if I let myself
go on any longer I imagine everybody else will wish so too,
so I'll steer clear of such fun topics as whether floogled sessions,
transport connections, and network-layer connectionless whatevers
(associations, maybe) are or aren't meaningful, muchless the
possible significance of floogling at the top, middle, or bottom
of a layer. (But it would be delightful to take them up one at a
time if anybody else feels like it.)
   cheers, map
P.S. In case anybody's curious, Sutton was "Willie-the-Actor," and
when asked why he robbed all those banks he's alleged to have replied
"Because that's where they keep the money."
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