Performance Analysis of Encryption in Securing the Live Migration of Virtual Machines

Virtual machine (VM) migration is a technique for transferring the execution state of a VM from one physical host to another. While VM migration is critical for load balancing, consolidation, and server maintenance in virtualized data centers, it can also increase security risks. During VM migration, an attacker with sufficient privileges can compromise a VM by modifying its memory contents during transit to subvert its applications or the guest operating system. One could maintain dedicated, and presumably more secure, control networks to carry the migration traffic, but at significant hardware and administrative complexity. Alternatively, one could encrypt the migration traffic, which eliminates the need for dedicated control networks, but might introduce performance overheads. To date, there has been no systematic study of how encryption affects VM migration, especially in high-bandwidth low-delay networks that are common within data centers. In this paper, we present a study of the impact of AES and 3DES encryption algorithms on two widely used live VM migration approaches - pre-copy and post-copy. Our key findings are as follows. The encryption algorithm used can have a significant impact on the total migration time. The impact of encryption on downtime varies with the type of the migration technique. The overhead of encryption also depends upon the relative speeds of source and target machines. Finally, an application's performance within a VM during encrypted migration varies with the type of the application and the migration mechanism.