Reconsidering Leakage Prevention in MapReduce

Trusted Execution Environment introduces a promising avenue for protecting MapReduce jobs on untrusted cloud environment. However existing works pointed out that simply protecting MapReduce workers with trusted execution environment and protecting cross-worker communications with encryption still leak information via cross-worker traffic volumes. Although several countermeasures were proposed to defeat such a side-channel attack, in this paper, we showed that previous countermeasures not only fail in completely eliminating such a side-channel, but also have limitations from other aspects. To address all the discovered limitations, we further discussed possible strategies.