Secure communication between set-top boxes (STBs) and smart cards is directly related to the benefit of the service providers and the legal rights of users, while key exchange is the essential part of a secure communication. In 2004, Jiang et al. proposed a key exchange protocol for STBs and smart cards based upon Schnorr's digital signature protocol and a one-way hash function. This paper, however, demonstrates that Jiang et al.'s protocol is vulnerable to an impersonation attack and does not

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... rovide perfect forward secrecy. In addition, in order to isolate such problems, we present a new secure key exchange protocol based on a one-way hash function and Diffie-Hellman key exchange algorithm. , South Korea. His current research interests are cryptography, authentication technologies, smart card security, network security, DRM security, and steganography. He has published over a hundred technical and scientific international journals on a variety of information security topics.