基于FPGA集群的Office口令恢复优化实现

Optimized Implementation of Office Password Recovery Based on FPGA Cluster

口令恢复是口令找回和电子取证的关键技术,而加密的Office文档被广泛使用,实现Office加密文档的有效恢复对信息安全具有重要的意义。口令恢复是计算密集型任务,需要硬件加速来实现恢复过程,传统的CPU和GPU受限于处理器结构,大大限制了口令验证速度的进一步提升。基于此,文中提出了基于FPGA集群的口令恢复系统。通过详细分析Office加密机制,给出了各版本Office的口令恢复流程。其次,在FPGA上以流水线结构优化了核心Hash算法,以LUT(Look Up Table)合并运算优化改进了AES(Advanced Encryption Standard)算法,以高速并行实现了口令生成算法。同时,以多算子并行设计了FPGA整体架构,实现了Office口令的快速恢复。最后,采用FPGA加速卡搭建集群,配合动态口令切分策略,充分发掘了FPGA低功耗高性能的计算特性。实验结果表明,无论在计算速度还是能效比上,优化后的FPGA加速卡都是GPU的2倍以上,具有明显的优势,非常适合大规模部署于云端,以缩短恢复时间找回口令。

Password recovery is the key technology of password back and electronic forensics.While encrypted office documents are widely used,it is of great significance to achieve the effective recovery of office encrypted documents for information security.Password recovery is a computation-intensive task and requires hardware acceleration to implement the recovery process.Traditional CPUs and GPUs are limited by the processor structure,which greatly limits the further increase in password verification speed.In view of this,this paper proposes a password recovery system based on FPGA cluster.Through detailed analysis of the office encryption mechanism,the password recovery process of each version of office is given.Secondly,the core Hash algorithm is optimized with a pipeline structure on FPGA,the AES algorithm is improved by LUT merging operation,and the password generation algorithm is implemented in parallel at high speed.At the same time,the architecture of FPGA is designed with multiple algorithm sub-modules in parallel,which realizes the fast recovery of office password.Finally,the FPGA accelerator card is used to build the cluster,and the dynamic password segmentation strategy is used to fully explore the low-power and high-performance computing features of FPGAs.The experimental results show that the optimized FPGA accelerator card is more than twice the GPU in terms of computing speed and energy efficiency ratio,which has obvious advantages and is very suitable for large-scale deployment in the cloud to shorten the recovery time and retrieve the password.