[122434] in cryptography@c2.net mail archive
RE: New result in predicate encryption: disjunction support
daemon@ATHENA.MIT.EDU (Jonathan Katz)
Sun May 4 19:55:02 2008
Date: Sun, 4 May 2008 13:20:19 -0400 (EDT)
From: Jonathan Katz <jkatz@cs.umd.edu>
To: cryptography@metzdowd.com
In-Reply-To: <003701c8ae05$24766eb0$6901a8c0@BigDell>
On Sun, 4 May 2008, Scott Guthery wrote:
> One useful application of the Katz/Sahai/Waters work is a counter to traffic
> analysis. One can send the same message to everyone but ensure that only a
> defined subset can read the message by proper key management. What is less
> clear is how to ensure that decrytion with the wrong key doesn't yield an
> understandable (and actionable) message.
This is actually pretty easy to do by, e.g., padding all valid messages
with sufficiently-many 0s. Decryption with an incorrect key will result in
something "random" that is unlikely to end with the requisite number of 0s
(and so will be discarded).
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