Title:
DOCUMENT PROTECTING METHOD AND DEVICE AS WELL AS DOCUMENT USED THEREFOR
Document Type and Number:
Japanese Patent JPS5774772
Kind Code:
A
Abstract:
1. A method of producing and later checking documents which are to be protected from counterfeiting, falsification and misuse using a pair of codes or algorithms which are connected via a "trap-door" function and consist of a code (B) which has to be kept secret and a code (A) which does not have to be kept secret, wherein uncoded information in clear (K) is entered on the document to be protected during its preparation, coded information (C) is derived from the uncoded information in clear, using the code or algorithm (B) which is kept secret and is likewise entered on the document to be protected, and wherein, during the checking of the document, the coded information (C) is decoded using the code or algorithm (A) which does not have to be kept secret, the information (K) thus obtained is compared with the uncoded information (K) present on the document and the validity of the document is made evident with reference to the result of the comparison characterised in that, during the preparation of the document, the uncoded information in clear (K) is stored in a store (4) of the document which is accessible or not accessible from the outside and the coded information (C) is stored in a store (3) of the document which is not accessible from the outside, and that during the checking of the document, following an external start instruction, the decoding of the coded information (C) and the comparison of the information (K) thus obtained with the uncoded information (K) stored on the document are carried out in circuit stages (12, 13) provided on the document itself and the result of the comparison is made evident to the outside.
Inventors:
KURUTO SHIETSUFUERU
Application Number:
JP17148680A
Publication Date:
May 11, 1982
Filing Date:
December 06, 1980
Export Citation:
Assignee:
GUREI RABU ESUDABURITSUSHIYUME
International Classes:
G06F21/12; G06F21/14; G09C1/00; G06K19/06; G06K19/073; G07C11/00; G07D7/00; G07D7/0047; G07D7/01; G07F7/10; G07F7/12; (IPC1-7): G09C5/00