1. A method of encrypting hierarchically structured information, the hierarchically structured information including at least a first set and a second set of hierarchically structured information, including a particular node and one or more descendent nodes, each node having a name and zero or more additional data for the node, the method comprising: encrypting the name of the particular node at a computer; storing the encrypted name at the computer; storing data associated with at least one descendent node of the one or more descendent nodes in unencrypted form at the computer; storing the one or more descendent nodes with parent-child relationships of the one or more descendent nodes exposed at the computer; and performing a differencing operation on the hierarchically structured information for identifying differences between the first set and the second set of hierarchically structured information, wherein said differencing operation comprises: identifying elements of the first set and of the second set of hierarchically structured information and their parent-child relationships at the computer: comparing corresponding elements of the first set and of the second set of hierarchically structured information at the computer: and identifying differences between the first set and the second set of hierarchically, structured information at the computer.