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. 18. The processing device-readable storage medium of claim 15 , wherein the instructions are executable to further: receive a query referencing a particular sensitive character string, the query to access data in a database, wherein the ordered set of sensitive character strings includes the particular sensitive character string, and wherein the desensitizing includes desensitizing the particular sensitive character string.