The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 25, 2000
Filed:
Jan. 22, 1998
Jaakko Astola, Kangasala, FI;
Pauli Kuosmanen, Kangasala, FI;
Nokia Technology GmbH, Bochum, DE;
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) or it can be a sealed authentication coding circuit.