Transistor integrated device, particularly usable for coding purposes
US4409434A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 1980 |
| Grant date | Oct 11, 1983 |
| Priority date | — |
| Expiry date | Dec 1, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D89/00
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a transaction card such as a credit or payment card provided with an integrated circuit for performing and recording the transaction, communications between the card and an access terminal must be coded so as to prevent fraud attempts. An integrated circuit coding device for coding or decoding a message in accordance with a confidential coding key comprises active transistors, and passive transistors, i.e. permanently blocked and/or permanently conductive, interconnected in such a way that observation of such circuit by means of an electronic microscope does not allow the determination of the confidential key which is implemented by the circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.