Currently all HDFS RPCs performed by NNs/DNs/clients can be optionally encrypted. However, actual data read or written between DNs and clients (or DNs to DNs) is sent in the clear. When processing sensitive data on a shared cluster, confidentiality of the data read/written from/to HDFS may be desired.
This change is already done in Hadoop 2 and trunk.
The task is to port this change to Hadoop 1.