Abstract: Techniques for protecting electronic documents from unauthorized access by insiders create a protected document fingerprint of each document to be protected and comparing a similar fingerprint of a suspected document or text. When the two fingerprints match to a certain degree of similarity, a security alert is activated. The techniques can be installed on devices in order to notify a security official, prevent an email from being sent; prevent a document from being printed, prevent packets from being forwarded, prevent copying of the suspect document to a removable medium and the like. A document fingerprint is created by algorithmically selecting words to be used in creating the fingerprint and algorithmically selecting characters from those words to be included in the document fingerprint. The techniques permit identification of text that comes from a protected document even if it has been retyped to rephrase the content of the protected document.