Xerox 5755, 5790, 5775, 5745, 5740, 5735 manual Algorithm, User Behavior, Overwrite Timing, Page 41 of

XEROX WorkCentre 5735/5740/5745/5755/5765/5775/5790 Information Assurance Disclosure Paper

4.5.1. Algorithm

The overwrite mechanism for both IIO and ODIO conforms to the U.S. Department of Defense Directive 5200.28-M (Section 7, Part 2, paragraph 7-2022.

The algorithm for the Image Overwrite feature is:

Step 1: Pattern #1 is written to the sectors containing temporary files (IIO) or to the entire spooling area of the disks (ODIO). (hex value 0x35 (ASCII “5”)).

Step 2: Pattern #2 is written to the sectors containing temporary files (IIO) or to the entire spooling area of the disks (ODIO). (hex value 0xCA (ASCII compliment of 5)).

Step 3: Pattern #3 is written to the sectors containing temporary files (IIO) or to the entire spooling area of the disks (ODIO). (hex value 0x97 (ASCII “ú”)).

Step 4: 10% of the overwritten area is sampled to ensure Pattern #3 was properly written. The 10% sampling is accomplished by sampling a random 10% of the overwritten area.

4.5.2. User Behavior

IIO can be enabled at the local UI only. Once enabled, IIO is invoked automatically immediately prior to the completion of a print, network scan, internet fax, network fax, or e-mail job. If IIO completes successfully, status is displayed in the Job Queue. However, if IIO fails, a popup will appear on the Local UI recommending that the user run ODIO, and a failure sheet will be printed.

ODIO may be invoked either from the Local UI in Tools Pathway or from the CentreWare Internet Services Web UI. Network functions will be delayed until the overwrite is completed. Copying is unavailable while the overwrite itself is underway, but copies may be made while the controller is booting.

Upon completion and verification of the ODIO process, a confirmation sheet is printed which indicates the status of the overwrite. The completion status can be successful, failed, cancelled, or timed-out.

Please note that invocation of ODIO will cause currently processing print jobs to be aborted. However, scan jobs will not be aborted and so ODIO might fail. The user should insure that all scan jobs have been completed before invoking ODIO.

Please refer to the customer documentation for a description on how failures are logged.

4.5.3. Overwrite Timing

The ODIO overwrite time is dependent on the type of hard disk in the product. The overwrite and reset average time is 10 minutes, but longer times are possible.

IIO is performed as a background operation, with no user-perceivable reduction in copy, print or scan performance.

2http://www.dtic.mil/whs/directives/corres/archives/520028m_0173/p520028m.pdf

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