Overcoming glitches and dissipation timing skews in design of DPA-resistant cryptographic hardware
Cryptographic embedded systems are vulnerable to Differential Power Analysis (DPA) attacks. In this paper, we propose a logic design style, called as Precharge Masked Reed-Muller Logic (PMRML) to overcome the glitch and Dissipation Timing Skew (DTS) problems in design of DPA-resistant cryptographic hardware. Both problems can significantly reduce the DPA-resistance. To our knowledge, the DTS problem and its countermeasure have not been reported. The PMRML design can be fully realized using common CMOS standard cell libraries. Furthermore, it can be used to implement universal functions since any Boolean function can be represented as the Reed-Muller form. An AES encryption module was implemented with multi-stage PMRML. The results show the efficiency and effectiveness of the PMRML design methodology.
In this paper, we study the behavior of voice over IP (VoIP) traffic over IEEE 802.11 wireless networks. Specifically, we propose a QoS provisioning mechanism for VoIP traffic, and suggest a practical solution to configuring the 802.lie enhanced distributed control access (EDCA) parameter sets for different types of traffic. With our mechanism, the EDCA parameter sets can be easily configured via software interface in off-the-shelf WiFi phone products and it is not required to modify the operations of access points or 802.11 MAC layer protocols. The performance of our mechanism is evaluated via ns-2 simulations and via laboratory experiments over Quanta's 02 dual-mode handsets. The results show our mechanism can provide effective and efficient QoS provisioning for VoIP traffic over IEEE 802.11 WLANs.