Method of secure remote access
First Claim
1. In a secure remote access system having a base unit and a remote unit coupled by a communication link, the remote unit containing a private key known only to that particular remote unit, a method of authentication of the remote unit comprising the steps of:
- registering the remote unit with the base unit by establishing a randomly selected common key through communication between the base unit and the remote unit in a manner that maintains the privacy of the common key, and storing the common key and an encrypted form of the common key in the base unit;
then authenticating the remote unit by encrypting a random number with the common key in the base unit, passing the encrypted common key and a challenge number from the base unit to the remote unit wherein the challenge number comprises one of the random number and the encrypted random number, decrypting the common key in the remote unit, operating on the challenge number with the common key in the remote unit and passing the result to the base unit, and comparing the results.
2 Assignments
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Accused Products
Abstract
Access to a vehicle by a remote electronic key via a radio link is secured by an exchange of encrypted signals. A remote unit having a secret number is introduced to a base unit and a common key is agreed upon by an exponential key exchange. The common key is encrypted using the secret number and stored in the base unit. Thereafter, the base unit is able to authenticate the identity of the remote unit by sending the encrypted common key and a random number to the remote unit which decrypts the key and uses it to encrypt the random number. The random number is also encrypted in the base unit and compared with the encrypted random number from the remote unit.
198 Citations
12 Claims
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1. In a secure remote access system having a base unit and a remote unit coupled by a communication link, the remote unit containing a private key known only to that particular remote unit, a method of authentication of the remote unit comprising the steps of:
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registering the remote unit with the base unit by establishing a randomly selected common key through communication between the base unit and the remote unit in a manner that maintains the privacy of the common key, and storing the common key and an encrypted form of the common key in the base unit; then authenticating the remote unit by encrypting a random number with the common key in the base unit, passing the encrypted common key and a challenge number from the base unit to the remote unit wherein the challenge number comprises one of the random number and the encrypted random number, decrypting the common key in the remote unit, operating on the challenge number with the common key in the remote unit and passing the result to the base unit, and comparing the results. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a secure remote access system having a base unit and a remote unit coupled by a communication link, a method of encrypted communication comprising the steps of:
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secretly establishing a common key by communication between the base unit and the remote unit; encrypting the common key in the remote unit by using a secret code in the remote unit; passing the encrypted common key to the base unit for storage in the base unit; then authenticating the remote unit by passing the encrypted common key and a random number from the base unit to the remote unit, decrypting the common key in the remote unit, encrypting the random number with the common key in both units, passing the result from the remote unit to the base unit, and comparing the results.
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9. In a secure remote access system for an automotive vehicle having a base unit in the vehicle and a remote unit coupled to the base unit by a radio link subject to eavesdropping, the remote unit having a secret code, a method of authenticating the remote unit comprising the steps of:
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initializing the system by providing the base unit and the remote unit with a common key, and encrypting the common key in the remote unit using the secret code for encryption and passing the encrypted common key via the radio link to the base unit for storage; and
thenauthenticating the remote unit when access is attempted by passing the encrypted common key and a random number to the remote unit, decrypting the common key in the remote unit, encrypting the random number with the common key in both units, and comparing the encrypted random numbers to determine authenticity. - View Dependent Claims (10, 11, 12)
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Specification