US 7,321,737 B2 | ||
System for authenticating modules installed in machines, such as printing apparatus | ||
Kevin Swann, St. Albans (United Kingdom); and Roger Huggins, Knebworth (United Kingdom) | ||
Assigned to Xerox Corporation, Norwalk, Conn. (US) | ||
Filed on Jun. 30, 2005, as Appl. No. 11/172,309. | ||
Prior Publication US 2007/0003293 A1, Jan. 04, 2007 | ||
Int. Cl. G03G 15/00 (2006.01) |
U.S. Cl. 399—12 | 18 Claims |
1. A method of operating a machine, comprising:
installing into the machine a module having a first random number generator associated therewith;
incidental to installing the module, initiating a second random number generator associated with the machine;
each of the first random number generator and the second random number generator outputting a series of random numbers over
time; and
at a predetermined time, checking that a random number recently output by the second random generator is of a predetermined
relationship to a random number recently output by the first random number generator.
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