15. A processing device-readable storage medium storing instructions that upon execution cause a processing device to: generate an ordered set of sensitive character strings; store in a memory a tree corresponding to the ordered set of sensitive character strings, wherein the tree comprises a plurality of nodes containing sensitive characters of the sensitive character strings and leaf nodes corresponding to ends of the sensitive character strings; provide a set of ordered desensitization characters; desensitize the sensitive characters on the nodes of the tree in depth-first order, wherein the desensitizing includes assigning selected desensitization characters from the set of ordered desensitization characters to respective ones of the sensitive characters on the nodes of the tree; and upon reaching a particular leaf node, store in the memory a desensitized string extending between a root node and the particular leaf node, wherein the desensitized string includes a group of the assigned desensitization characters.
15. A processing device-readable storage medium storing instructions that upon execution cause a processing device to: generate an ordered set of sensitive character strings; store in a memory a tree corresponding to the ordered set of sensitive character strings, wherein the tree comprises a plurality of nodes containing sensitive characters of the sensitive character strings and leaf nodes corresponding to ends of the sensitive character strings; provide a set of ordered desensitization characters; desensitize the sensitive characters on the nodes of the tree in depth-first order, wherein the desensitizing includes assigning selected desensitization characters from the set of ordered desensitization characters to respective ones of the sensitive characters on the nodes of the tree; and upon reaching a particular leaf node, store in the memory a desensitized string extending between a root node and the particular leaf node, wherein the desensitized string includes a group of the assigned desensitization characters. 16. The processing device-readable storage medium as recited in claim 15 , wherein the instructions are executable to: generate a first portion of the tree to store in the memory, wherein the first portion corresponds to a first portion of the ordered set of sensitive character strings; and wherein desensitizing the sensitive characters comprises: determining whether the sensitive characters are on an unknown node; and if so, restricting selection of desensitization characters for assignment to the unknown node to a limited portion of the set of ordered desensitization characters, else, selecting desensitization characters from the complete set of ordered desensitization characters.