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Secure Printing or Improved Process of Printing Impress Encoded Documents



Technical Challenge:

To assure that a file is printed correctly on a printer.


An electronic file can contain N-number of printed pages. For example, a word document may be thousands of pages long; however, it is all contained in one electronic file stored on a hard drive or floppy. Printing all or part of this file requires the "trust" of the user that what gets printed is exactly what was in the file. This process uses mathematical methods to ensure that what gets printed is exactly what is in the electronic file.

Embedded in the print language (PostScript or IMPRESS) are sequences and checksum values. The sequence ensures that the records are ordered without the deletion or insertion of "illegal" print records. The checksum value is a mathematical function of the print language data. The stored checksum value is compared to the run-time computed value to ensure that no data has been changed. These values are checked every time the print process interacts with the data.

Demonstration Capability:

A printer can easily be set up to demonstrate the printer's capabilities.

Potential Commercial Application(s):

This software method can be used for any similarly formatted files.

Patent Status:

Issued: United States Patent Number 6657740 (Updated)

Reference Number: 1115

If you are interested in exploring this technology further, please express your interest in writing to the:

National Security Agency
NSA Technology Transfer Program
9800 Savage Road, Suite 6541
Fort George G. Meade, Maryland 20755-6541


Date Posted: Jan 15, 2009 | Last Modified: Jan 15, 2009 | Last Reviewed: Jan 15 2009