Resynchronizing transmitters to receivers for secure vehicle entry using cryptography or rolling code
First Claim
1. A method of synchronizing transmitter and receiver in a keyless entry system of the type which uses encrypted access codes to prevent unauthorized access, comprising:
- storing secret information data in the transmitter and storing the same secret information data in the receiver, said secret information including a resynchronization authorization code;
storing at least a first access code in said transmitter and at least a first access code in said receiver, the access codes serving to permit access if transmitter and receiver first access codes match and to prevent access if transmitter and receiver first access codes do not match;
initiating a resynchronization sequence and in response to initiating a resynchronization sequence, generating a first random number access code at said transmitter;
using said transmitter to transmit said resynchronization authorization code and said first random number access code to said receiver;
substituting said first random number access code for the first access code in said transmitter;
in said receiver comparing the transmitted resynchronization authorization code with the resynchronization authorization code stored in said receiver;
if the transmitted resynchronization authorization code and the resynchronization authorization code stored in said receiver match, substituting said first random number access code for the first access code in said receiver;
whereby the first access codes of transmitter and receiver are reset to match one another, thereby synchronizing transmitter and receiver.
11 Assignments
0 Petitions
Accused Products
Abstract
Secret Information is stored in the transmitter and receiver of the keyless entry system. The information includes a resynchronization authorization code. When resynchronization is requested by the user pressing the appropriate key fob button, a random number is generated in the transmitter and sent to the receiver along with the resynchronization authorization code. The receiver tests the authorization code received with its stored code. If the codes match, the receiver substitutes the random number received from the transmitter for its existing stored access code, thereby placing the transmitter and receiver back in synchronization.
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Citations
7 Claims
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1. A method of synchronizing transmitter and receiver in a keyless entry system of the type which uses encrypted access codes to prevent unauthorized access, comprising:
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storing secret information data in the transmitter and storing the same secret information data in the receiver, said secret information including a resynchronization authorization code; storing at least a first access code in said transmitter and at least a first access code in said receiver, the access codes serving to permit access if transmitter and receiver first access codes match and to prevent access if transmitter and receiver first access codes do not match; initiating a resynchronization sequence and in response to initiating a resynchronization sequence, generating a first random number access code at said transmitter; using said transmitter to transmit said resynchronization authorization code and said first random number access code to said receiver; substituting said first random number access code for the first access code in said transmitter; in said receiver comparing the transmitted resynchronization authorization code with the resynchronization authorization code stored in said receiver; if the transmitted resynchronization authorization code and the resynchronization authorization code stored in said receiver match, substituting said first random number access code for the first access code in said receiver; whereby the first access codes of transmitter and receiver are reset to match one another, thereby synchronizing transmitter and receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification