Procedure for increasing the manipulation security for a bi-directional contactless data transmission
US6842493B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 11, 2000 |
| Grant date | Jan 11, 2005 |
| Priority date | — |
| Expiry date | Sep 27, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/0008
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a bi-directional contactless data transmission, a procedure aims to prevent the communication distance from being extended by unauthorized persons using radio repeaters. The procedure involves establishing a fixed relationship of a selected physical parameter of an electromagnetic signal. For example, the frequency of the signal received by a transponder is multiplied with a number to provide a different frequency, and a response signal having this different frequency is transmitted back to a base unit. In the base unit, the received frequency of this response signal is divided by the same number and the result is compared to the frequency of the originally emitted signal. If the resulting difference is below a preset threshold, then there is a fixed frequency relationship between the two signals, the process concludes that there has been no unauthorized extension of the communication distance by using repeaters, and the further authentication is carried out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.