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\ctrline{INVENTION DISCLOSURE BY ROBERT FLOYD AND JOHN MCCARTHY}
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\ctrline{February 6, 1980}
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\ctrline{THEFT PROTECTION BY PROVIDING EQUIPMENT WITH PASSWORDS}
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	This invention is a scheme for protecting equipment from
theft by making it inoperable without a password.

	Electronic equipment to be protected includes computers,
calculators, televisions, and high fidelity equipment and any other
having a substantial electronic component not easily removable.

	We suppose that the equipment uses an integrated circuit
as an essential component or can have one added.  We also suppose
that it has a numerical keyboard or can have one added.  The keyboard
can be the same as is used for some other purpose.

	A 10 or more digit randomly chosen password different for
each unit is included in the integrated circuit.  When power is
first turned on, the unit requires the entry of this password
before it will function.

	Since the entry of ten digits is inconvenient each time the
equipment is used, shorter temporary passwords may be entered once
the original ten digit password has been given.  If the user feels
that the equipment is safe for the time being this can even be the
null password, i.e. the equipment operates without password.  The
memory of the temporary password is maintained in battery supported
CMOS when the equipment is turned off.  The user may also set a
lifetime for the temporary password, so that after this time, the
long password must be used to restore function.

	This means that stolen equipment cannot be used without
the short password, and its continued functioning cannot be
guaranteed without the long password.

	Manufacturers may (if they choose or are required to) keep
records of the long passwords, which they will furnish to users who
lose theirs, provided the equipment hasn't been reported stolen and
provided the requester furnishes satisfactory identification.

	Besides protecting the ultimate purchaser, the system can
protect the equipment in transit between manufacturer and dealer,
since the passwords can be sent by mail separately from the equipment
itself.

	The equipment easiest to protect is a calculator since it
uses a keyboard and ROM memory already.  The more closely the
password is integrated with the essential function of the equipment,
the harder it is to steal, but even if the password unit is an
add-on, it will thwart most present day thieves and fences.
Even if the password checker can be disconnected, it potential
purchasers of the stolen equipment will not find it so easy as at
present to believe that the equipment is not stolen.

	If legislatures think it worthwhile, laws can be passed making
possession of passworded equipment without the password {\it prima facie}
evidence of unlawful possession of stolen goods.

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