Xerox 6180N Generic MICR Fundamentals Guide  - Page 135

Security Tampering methods There are several methods by which data on a check may be altered. The security papers on which negotiable documents are printed are designed to thwart these forms of tampering. Chemical tampering Many inks can be affected by particular chemicals, making chemical alteration of checks possible. These chemicals could be some combination of solvent and bleach. Certain inks can be bleached without materially affecting the paper stock. Other inks can be selectively removed without affecting the rest of the image. Select check stocks that contain materials that make altering the printed transaction information difficult. For example, if ballpoint pens will be used to complete the check, the paper should contain indicators for ballpoint ink solvents. If organic dye based inks, which are susceptible to bleaching, will be used, select papers containing a bleach indicator. (Because dry ink images are encapsulated in a plastic resin, they are almost impossible to bleach.) Check stock must also remain compatible with the MICR printing system on which it is used. Some chemical security features can damage printer subsystems. A marginally effective security feature could actually degrade overall document security. Mechanical tampering Mechanical alterations include erasing, picking ink out of a document, and scraping to remove sections of the original document. The part of the image that is removed is replaced with a section that looks similar. Mechanical alterations are often attempted on xerographic images. Ways to discourage this kind of alteration include: • Repeating critical information at several locations on the document. This turns a simple change of vital information into an extensive modification of large areas of the document. Generic MICR Fundamentals Guide 8-7