very short plaintexts symmetrically encrypted
wk at gnupg.org
Tue Jan 12 09:35:17 CET 2010
On Mon, 11 Jan 2010 13:06:03 -0500, lists.gnupg-users at mephisto.fastmail.net wrote:
> Forgive me, but how is a MitM attack possible against a symmetric cypher
> using a shared, secret key?
For example by swapping messages. Two messages are sent on two
out-of-band events one which says Yes and the other says No. If you
can mount an active MitM attack you can revert the meaning. A MitM
may also inject faults to make the received message look like a
transmission error and thereby triggering another message.
Right, you can counter such attacks by adding more information to the
message. However, the original post was about two short messages.
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