11. A system comprising: a memory to store a plurality of classified data patterns for personal identifiers, the plurality of classified data patterns corresponding to variations of personal identifier formats, the personal identifiers including confidential information of a plurality of entities; a processor, coupled to the memory, to: search a text document for data expressed in a format that matches any of the plurality of classified data patterns corresponding to the variations of personal identifier formats, find, in the text document, one or more personal identifier candidates matching any of the plurality of classified data patterns, and validate each of the personal identifier candidates using one or more personal identifier validators to provide accurate detection of the confidential information in the text document.
15. The system of claim 11 wherein the validators comprise one or more of a checksum algorithm, a check against valid ranges of numbers within a personal identifier candidate, a check against invalid ranges of numbers within a personal identifier candidate, a check against invalid personal identifiers, a check for a valid prefix of a personal identifier candidate, a check for a valid suffix of a personal identifier candidate, a check for a valid format of a personal identifier candidate, a check for valid digits within a personal identifier candidate, a check for a valid number of digits or characters within a personal identifier candidate, or a search of the document for one or more keywords.