Cryptanalysis of a convertible authenticated encryption scheme based on the ElGamal cryptosystem
Fagen Li, Zhiguang Qin · IETE Technical Review · 2010
AbstractA convertible authenticated encryption scheme allows a designated recipient to retrieve an authenticated ciphertext and convert the authenticated ciphertext into an ordinary signature. Recently, Lee, Hwang, and Tzeng proposed a new convertible authenticated encryption scheme based on the ElGamal cryptosystem. In this paper, we show that the Lee-Hwang-Tzeng scheme is not secure against chosen plaintext attacks. In addition, we give a solution to repair it.