Integrated circuits with persistent data storage
First Claim
1. A method for a radio frequency identification (RFID) tag comprising:
- receiving a first code transmitted by an RFID reader, the first code generated by an XOR calculation; and
comparing a second code within the tag to the first code;
if the first code and second code do not match, muting the tag, wherein the muting the tag comprises creating a time delay of at least 1 second to prevent receiving other codes by the tag and wherein the first code is an access code.
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Accused Products
Abstract
The circuitry introduced in this invention selectively slows down the functioning of an electronic circuit maintaining a particular state for a prolonged period of time. This circuitry is used not only to achieve the desired effect in maintaining security from electronic thieves trying to circumvent codes but also in other applications such as enabling a circuit to continue to function in the event of a brief loss of power. For example, in an RFID system, if a reader is frequency hopping, a tag loses power for as long as about 400 milliseconds when the reader changes to other frequencies. In a preferred embodiment, the disclosed circuitry is used in conjunction with a destruct sequence.
92 Citations
15 Claims
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1. A method for a radio frequency identification (RFID) tag comprising:
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receiving a first code transmitted by an RFID reader, the first code generated by an XOR calculation; and comparing a second code within the tag to the first code; if the first code and second code do not match, muting the tag, wherein the muting the tag comprises creating a time delay of at least 1 second to prevent receiving other codes by the tag and wherein the first code is an access code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for a passive radio frequency identification (RFID) tag comprising:
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receiving an access code transmitted by a reader, the access code generated by an XOR calculation; comparing a second code within the passive RFID tag to the access code; and if the access code and second code do not match, muting the passive RFID tag, wherein the passive RFID tag includes a dipole antenna, wherein the muting the tag comprises creating a time delay of at least 1 second to prevent receiving other codes by the tag, and wherein the passive RFID tag is configured for a half-duplex, reader talks first protocol. - View Dependent Claims (11)
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12. A method for a radio frequency identification (RFID) reader comprising:
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transmitting, by the RFID reader, an access code, the access code generated by an XOR calculation; if the access code matches a second code contained within an RFID tag, receiving a CRC code from the RFID tag, wherein the RFID reader includes a linear antenna. - View Dependent Claims (13, 14, 15)
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Specification