Paper 2005/054

Comment on cryptanalysis of Tseng et al.¡¦s authenticated encryption schemes

Yi-Hwa Chen and Jinn-Ke Jan

Abstract

Recently, Xie and Yu proposed a forgery attack on the Tseng et al¡¦s authenticated encryption schemes and showed that their schemes are not secure in two cases: the specified verifier substitutes his secret key, or the signer generates the signature with these schemes for two or more specified verifiers. In addition, Xie and Yu made a small modification for the Tseng et al¡¦s schemes and claimed that the modified schemes can satisfy the security requirement. However, we show that the modified schemes are still insecure.

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