Hiding a authentication code in an electric signal
US6094722A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 22, 1998 |
| Grant date | Jul 25, 2000 |
| Priority date | — |
| Expiry date | Jan 22, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/328
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In order to hide an authentication code or signature (101, 402, 504) in an electric signal (100, 400, 401), which consists of data parts with a certain value, certain data parts are selected from the electric signal for processing on the basis of the contents of the authentication code. The value of each data part selected for processing is re-determined by a filter (200, 403, 504), which uses certain other predetermined data parts of the electric signal as input data. For detecting the authentication coding, the signal is filtered with the same filter (403) and those data parts (406) which have their value unchanged after the second filtering are marked. The electric signal can be a file (particularly an image file) or a temporally continuous signal. The device for implementing the method comprises a memory (501, 502) for saving the electric signal and a processing unit (500) for reading the data from the memory and for changing the value of its data parts. The device also comprises a filter (503), which uses the other data parts of the signal as input data and which determines the new value of the data parts selected for processing. The device can interact with the user (506, 507…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.