Rolling code encryption process for remote keyless entry system
First Claim
1. A method of generating a sequence of encoded data bits for a remote keyless entry system, said method comprising the steps of:
- providing a first pseudo random number generator including a first shift register having a predetermined number of bit locations and a first logic gate;
cycling the first pseudo random number generator a first number of times, said step of cycling the first pseudo random number generator including the step of combining two predetermined bit locations of the first shift register through said first logic gate and applying the result to the first bit location of the first shift register;
providing a second pseudo random number generator including a second shift register having a predetermined number of bit locations and a second logic gate;
cycling the second pseudo random number generator a second number of times, said step of cycling the second pseudo random number generator including the step of combining two predetermined bit locations of the second shift register through said second logic gate and applying the result to the first bit location of the second shift register; and
combining through a plurality of third logic gates each bit location of a series of bit locations of the first shift register with each corresponding bit location of a series of bit locations of the second shift register and applying the results to bit locations in a security code register.
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Accused Products
Abstract
An encryption process for a rolling code of a remote keyless entry system. The encryption process makes use of a command code shift register, a security code shift register, and a sequence code shift register in which the contents of these registers is transmitted from a portable transmitter to a receiver associated with the vehicle in order to perform a desirable function. The command code shift register provides the code of the function to be performed and the sequence code shift register provides a sequence code for updating the sequence of the receiver. The security code shift register includes a security code which is updated by a first and second pseudo random number generator after each transmission. Each of two pseudo random number generators include associated shift registers and exclusive NOR gates such that a first bit location and a tap bit location of each of the shift registers are exclusively NORed to provide a first bit location in the shift register. A series of the bit locations of the first and second shift registers are exclusively ORed together to set the bits of the security code register.
133 Citations
30 Claims
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1. A method of generating a sequence of encoded data bits for a remote keyless entry system, said method comprising the steps of:
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providing a first pseudo random number generator including a first shift register having a predetermined number of bit locations and a first logic gate; cycling the first pseudo random number generator a first number of times, said step of cycling the first pseudo random number generator including the step of combining two predetermined bit locations of the first shift register through said first logic gate and applying the result to the first bit location of the first shift register; providing a second pseudo random number generator including a second shift register having a predetermined number of bit locations and a second logic gate; cycling the second pseudo random number generator a second number of times, said step of cycling the second pseudo random number generator including the step of combining two predetermined bit locations of the second shift register through said second logic gate and applying the result to the first bit location of the second shift register; and combining through a plurality of third logic gates each bit location of a series of bit locations of the first shift register with each corresponding bit location of a series of bit locations of the second shift register and applying the results to bit locations in a security code register. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for generating a sequence of encoded data bits for a remote keyless entry system, said system comprising:
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a first pseudo random number generator including a first shift register having a predetermined number of bit locations and a first logic gate, wherein the bit values of each bit location of the first shift register are determined by combining through said first logic gate a tap bit location with a predetermined bit location of the first shift register, applying the output from said first logic gate to the first bit location of the first shift register and shifting the other bits over one position; a second pseudo random number generator including a second shift register having a predetermined number of bit locations and a second logic gate, wherein the bit values of each bit location of the second shift register are determined by combining through said logic gate a tap bit location and a predetermined bit location of the second shift register, applying the output from said second logic gate to the first bit location of the second bit register and shifting the other bits over one position; and a security code register having a predetermined number of bit locations, wherein the bit values of the bit locations of the security code register are determined by a series of logic gates, said series of logic gates combining each bit location of a series of bit locations of the first shift register and a series of corresponding bit location of the second shift registers and applying the results to the bit locations in the security code register. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. In a remote keyless entry system including a transmitter for transmitting an encoded data signal in accordance with the data word contained in a pseudo random number generator and a receiver for initiating the performance of a predefined task upon the receipt of a valid encoded data signal, the method of changing said encoded data signal after a transmission comprising the steps of:
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cycling said pseudo random number generator in a predetermined manner a number of times determined by the content of said generator so as to create a new data word in said generator; and transmitting an encoded data signal in accordance with said new data word. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. In a remote keyless entry system including a transmitter for transmitting an encoded data signal in accordance with the data word contained in a pseudo random number generator and a receiver for initiating the performance of a predefined task upon the receipt of a valid encoded data signal, the method of changing said encoded data signal after a transmission comprising the steps of:
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cycling said pseudo random number generator in accordance with a predetermined algorithmic process to produce a new data word; incrementing a sequence counter each time said cycling step is completed and a new data word is produced; and transmitting the content of said sequence counter and an encoded data signal in accordance with said new data word. - View Dependent Claims (25, 26)
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27. In a remote keyless entry system including a transmitter for transmitting an encoded data signal in accordance with an internally generated digital code word and a receiver for initiating the performance of a predefined task upon the receipt of a valid encoded data signal, the method of transmitting an encoded data signal comprising the steps of:
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providing a pseudo random number generator containing a digital code word comprised of a first number of data bits; cycling said pseudo random number generator in accordance with a predetermined algorithmic process to produce a new digital code word; and transmitting an encoded data signal in accordance with said new digital code word, wherein said encoded data signal contains a second number of encoded data bits less than said first number. - View Dependent Claims (28, 29, 30)
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Specification