Tie Manxia

A Correctness Proof of WAPI Certificate Authentication Protocol

WAPI certificate authentication protocol is the core and key component of WAPI security mechanism proposed by Chinese WLAN standard. This protocol adopts pubfic key cryptographic technique, ASUE (authentication supplicant entity) and AE (authenticator entity) implement the mutual identity authentication aided by their trusting third ASE (authentication security entity) to realize secure access and negotiate the corresponding BK. Using a formal logic of PCL, WAPI certificate authentication protocol is programmed and its security properties are proved. The results show that if all the entities involved in the protocol do not reveal their long-term keys or short-term keys, this protocol provides the properties of strong session authentication and key secrecy and achieves its predefined security goals.

A novel variable-rate MELP speech coder

In MELP coder, LPC coefficients are quantized to 25 bit/frame by MSVQ. The overall bit of MELP is 54 bit/frame, so more than 45% of the required bandwidth is spent on transmission of LPC coefficients. In this paper, based on LPC adaptive forward-backward quantization, a novel variable-rate MELP coder is proposed, in which linear prediction is done by using either the currently (forward LPC) or previously decoded (backward LPC) speech frame. The backward LPC scheme shall be applied, i.e., the LPC coefficients based on the previously decoded optimal speech frame are used to encode the current frame and only the time delay shall be transmitted to the decoder, so, average LPC bit number becomes smaller. Computer simulation shows significant average overall bit rate reduction is achieved without compromising the decoded speech quality.

The architecture and experiment of the customer premises network for a microwave ATM network

The paper discusses the architecture of an experimental research prototype for a microwave ATM customer premises network (CPN). Based on the architecture of the CPN, some of the key technologies for realizing the CPN functional blocks are discussed and part of the application specific integrated circuit (ASIC) design results are reported.<<ETX>>