[HGI-News] HGI-Seminar, Montag 23.04.2007: Plaintext awareness

[Newsletter des Horst Görtz Instituts]

          Dr. Alex Dent, Royal Holloway University of London

            Montag 23. April 2007, 13:15 Uhr IC 4 / 39-41

                        Plaintext awareness

Plaintext awareness is the property of an encryption scheme that means
that no attacker can create a ciphertext without "knowing" the underlying
plaintext (or that the ciphertext is invalid and won't be decrypted).
This renders a decryption oracle useless to an attacker. For any
ciphertext that the attacker submits to the decryption oracle, that
attacker must already know underlying plaintext; hence, they get no new
information when the decryption oracle returns this plaintext.

The notion of plaintext awareness was first developed as a method to
prove IND-CCA2 security. It has turned out not to be very useful in this
regard -- it is almost always significantly more difficult to prove that
a scheme is plaintext aware, than simply to prove that it is IND-CCA2
directly. However, it is useful in giving some insight as to why a
particular scheme achieves IND-CCA2 security.

This talk will survey the known results in standard model plaintext
awareness that have been developed over the last couple of years. This
will include discussions of several new results that have not yet been
published.

_____________________________________________________________________________
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-- 
Für das HGI, Michael Psarros <michael.psarros at nds.rub.de>