## Cryptology ePrint Archive: Report 2002/100

Encryption-Scheme Security in the Presence of Key-Dependent Messages

J. Black and P. Rogaway and T. Shrimpton

Abstract: Encryption that is only semantically secure should not be used on messages that depend on the underlying secret key; all bets are off when, for example,one encrypts using a shared key K the value K. Here we introduce a new notion of security, KDM security, appropriate for key-dependent messages. The notion makes sense in both the public-key and shared-key settings. For the latter we show that KDM security is easily achievable within the random-oracle model. By developing and achieving stronger notions of encryption-scheme security it is hoped that protocols which are proven secure under formal'' models of security can, in time, be safely realized by generically instantiating their primitives.

Category / Keywords: foundations / Definitions, formal'' cryptography, semantic security, symmetric encryption

Publication Info: To appear at SAC'02