iCloud: Identifying Faulty Cloudlets in Cloud Services

In cloud services, users can remotely store their data into the cloud so as to enjoy the on-demand high quality applications and services. However, when something goes wrong - information leakage or incorrect computing results - it is quite difficult to find out which cloudlet (i.e., individual node or server) should be responsible for that and whether there's solid evidence to prove it. In this paper, we introduce iCloud, a mechanism that can identify faulty cloudlets in cloud services. iCloud ensures that Byzantine faults whose effects are observed by a correct cloudlet can eventually be detected and irrefutably linked to a faulty cloudlet. On the other hand, iCloud can prevent a correct cloudlet from false accusations. iCloud works by maintaining a secure record of the messages sent and received by each cloudlet. iCloud is easily applicable: it only requires that cloudlets can sign messages, that a correct cloudlet's behaviors are deterministic, and that each cloudlet is periodically checked by a correct cloudlet.