To find the optimal deployment of allocating the maximum number of virtual Field Programmable Gate Array (vFPGA) in the minimum number of Field Programmable Gate Array (FPGA) in reconfigurable cryptographic resource pool, the traditional Ant Colony Optimization (ACO) algorithm was optimized, and a vFPGA deployment strategy based on optimized ACO algorithm with considering FPGAs’ characteristics and actual requirements was proposed. Firstly, the load balancing among FPGAs was achieved by giving ants the ability of perceiving resource status, at the same time, the frequent migration of vFPGAs was avoided. Secondly, the free space was designed to effectively reduce the Service Level Agreement (SLA) conflicts caused by dynamical demand change of tenants. Finally, CloudSim toolkit was extended to evaluate the performance of the proposed strategy through simulations on synthetic workflows. Simulation results show that the proposed strategy can reduce the usage number of FPGAs by improving the resource utilization under the promise of guaranteeing the system service quality.

Aiming at the problem of cryptographic performance being affected by the excessive interrupt transmission cost of the cipher device in virtual environment, an interrupt path optimization method for virtual cryptographic device with Reducing Context Switching (RCS) was proposed. Firstly, a host to Virtual Cipher Machine (VCM) relationship mapping table was established in the kernel of the virtual machine. Then, the types of the interrupt requests that the host transmits to the VCM were judged by the relational mapping table, and the unassigned types in VCM were registered. Finally, the interrupts were handled by the VCM interrupt handler directly. In the process, the system context switching overhead was reduced due to the host intervening and the cryptographic performance was improved. The speed at which the VCM executes the encryption was selected as a performance reference in the experiment. The results show that the speed of VCM using Advanced Encryption Standard (AES) algorithm is increased by 16.35% and that using Secure Hash Algorithm (SHA256) is increased by 12.25%.

To balance load in cryptography cloud systems, a Virtual cipher machine Scheduling Method based on Entropy Weight Evaluation (VSMEWE) was proposed. In order to improve the quality of cryptography service and economize resources of cryptography cloud effectively, a virtual cipher machine migration selection solution was presented, according to the comparison results of comprehensive evaluation values of cloud cipher machine. To achieve the best comprehensive evaluation values, it evaluated the resource states of cloud cipher machine with the main indexes including the utilizations of resources, such as CPU, memory, network bandwidth and throughput bandwidth of cipher card. Finally, a migration selection scheme of virtual cipher machine was decided by the scheduling method. Compared with Entropy algorithm and Baseline algorithm, the experimental results show that the proposed algorithm has characteristics of wholeness and chronergy, the effect of load balancing is improved, and the execution efficiency is increased by 6.8% and 22.7% respectively.

Since the current cloud task scheduling algorithm in the cryptography cloud environment cannot achieve the target that tasks are processed in real-time, a real-time threshold scheduling method based on rolling optimization window was proposed. Firstly, a cryptography cloud service architecture was given by integrating the link of key calling into the process of cryptographic task; secondly, to realize real-time scheduling, a cryptographic task scheduler model based on the rolling window and a throughput analysis model which was used to obtain the real-time throughput data were established; finally, to meet the objective needs of high-speed cryptographic service for cloud tenants, a throughput threshold scheduling algorithm was proposed, which migrates virtual cipher machine in real-time according to the changes of real-time throughput relative to throughput threshold. The simulation results show that compared with the method without the rolling optimization window or virtual machine migration technology, the proposed method has characteristics of shorter task completion time and lower CPU utility, meanwhile the real-time throughput of it can be continuously kept in 70%-85% of the network bandwidth, thus verifying its effectiveness and real-time performance in the cryptography cloud environment.