Patent ID: 8051286

Claim:
A vehicle antitheft system comprising: an immobilizer unit including: a first data processor; a memory storing a first set of computer instructions; a first communication part connected with the first data processor; a first antenna connected with the first communication part; a first storage connected with the first data processor, the first storage preliminarily storing first data for mutual authentication; and a second storage connected with the first data processor; the immobilizer unit further includes an information reception part connected with the first data processor; and a portable unit including: a second data processor; a memory storing a second set of computer instructions; a second communication part connected with the second data processor; a second antenna connected with the second communication part; a third storage connected with the second data processor, the third storage preliminarily storing the first data for mutual authentication; and a fourth storage connected with the second data processor, the fourth storage preliminarily storing second data for mutual authentication different from the first data for mutual authentication; wherein the first data processor executes the first set of computer instructions and the second data processor executes the second set of computer instructions to perform the following functions comprising: when a first instruction is fed into the information reception part, the first data processor and the second data processor authenticate each other by an authentication comprising: (1) the first data processor transmitting via the first antenna an encrypted data based on the first data for mutual authentication stored in the first storage and (2) the second data processor receiving the encrypted data via the second antenna, decrypting the encrypted data and comparing the decrypted data to the first data for mutual authentication stored in the third storage; and the first data processor and the second data processor, responsive to the authentication between the first data processor and the second data processor, interchange the second data for mutual authentication to set the portable unit for the immobilizer unit in a way comprising: 1) the second data processor transmitting the second data for mutual authentication stored in the fourth storage via the second antenna, 2) the first data processor further storing, into the second storage, the second data for mutual authentication received via the first antenna and transmitting the second data for mutual authentication stored in the second storage via the first antenna, and 3) the second data processor further storing, into the third storage, the second data for mutual authentication received via the second antenna.