Conflict-based cache side-channel attacks against the last-level cache (LLC) is a widely exploited method for information leaking. Cache randomization has recently been accepted as a promising defense. Most of recent designs randomize skewed caches rather than classic set-associative caches; however, skewed caches incur substantial performance overhead both in area and runtime. We cautiously argue that randomized set-associative caches can be sufficiently strengthened and possess a better chance to be adopted in the near future. For the first time, a dynamically randomized set-associative cache has been implemented in the LLC of a Linux capable multicore processor. A single-cycle hash logic is designed for randomizing the cache set indices. A multi-step relocation scheme is used to reduce the cost in remapping the cache layout. The randomized cache layout is remapped periodically for limiting the time window available to attackers. An attack detector is implemented to catch attacks in action and consequently trigger extra remaps. The evaluation results show that the randomized LLC has been sufficiently strengthened to thwart all existing fast algorithms for searching eviction sets with only marginal runtime overhead, and small area and power overhead.

Eviction sets are essential components of the conflict-based cache side-channel attacks. However, it is not an easy task to construct eviction sets on modern Intel processors. As a promising defense against conflict-based cache side-channels, dynamic cache randomization makes the construction of eviction sets even more difficult by periodically randomizing the mapping between addresses and cache set indices. It forces attackers to develop fast search algorithms to find an eviction set at runtime with the lowest latency. Several fast search algorithms have been proposed in recent years. By using these algorithms, attackers regain the capability of launching useful attacks on dynamically randomized caches. Consequently, a detector was recently introduced to catch the fast search algorithms in action according to the uneven distribution of cache evictions. All existing fast search algorithms fail to work.

This paper presents a new isolated bidirectional DC/DC converter for auxiliary power supplies in electric vehicles where high power density, bidirectional power flow and electric isolation are required. Compared to conventional bidirectional converters, this modified half-bridge circuit further minimizes components to 2 capacitors without any other change based on the existing highest power density circuit. With a novel PWM plus phase-shift (PPS) control strategy, it minimizes device current stresses over a wide input voltage range. Moreover, a natural zero-voltage switching method for the whole switches is achieved without additional device to reduce switching loss and device inrush voltage stresses. These advantages make the new converter promising for high power density applications, especially to overcome the high device current stresses problem caused by wide range ultra-capacitor voltage variation. In this paper, firstly, a complete design consideration and principle of the new topology is presented; secondly, an analysis of static state mode is provided; finally, a 15V/50W prototype is built up after a 60V/4kW modeling simulation on computer and it successfully proved this converter's device current stresses minimization and high power density characteristics.