On the security of virtual machine migration and related topics

The extension of trusted computing to virtual environments in order to provide secure storage and ensure system integrity presents several challenges. In particular, techniques to share a hardware TPM between several virtual machines (VM) on the same host and to appropriately secure these VMs during migration need to be devised. In this work, we provide a comprehensive overview of trusted computing and its extension to virtualization by means of virtual TPMs (vTPM). We analyze existing vTPM designs and related VM-vTPM migration protocols and derive a set of requirements for the secure VM-vTPM migration. We then propose a secure migration protocol using a novel vTPM key hierarchy that satisfies these requirements. We implement our protocol and evaluate its performance using different ciphers and VM RAM sizes. Our results show that both RC4 and 128-bit AES are efficient as underlying ciphers as opposed to 3DES which introduces a significant overhead on the migration process. Moreover, the end-to-end migration time experienced by the end user (using RC4 or 128-bit AES as the underlying cipher) increases only by approximately 10% compared to the insecure migration when VM RAM size is larger than 512 MB. This overhead may be tolerable in certain applications depending on the used hardware. Thus, secure VM-vTPM migration can be practical.