Patent ID: 7080252

Claim:
A method for making an electronic exchange of an image using a digital signature, wherein the image to be exchanged is obtained by processing an original image of written information read out of a recording medium, between a data transmission side and a data reception side via a network, said method comprising: a data transmission step on said data transmission side; and a data reception step on said data reception side; wherein said data transmission step comprises: a first step of processing said original image so as to produce partial image which forms a part of said original image, a second step of applying a digital signature to said original image so as to produce first signed data, a third step of ciphering said first signed data with a public key of said data reception side so as to produce a ciphered signed data, a fourth step of merging said partial image and said first signed data, applying a one-way function to the merged data, and ciphering an output of said one-way function with a secret key of said data transmission side so as to obtain second signed data, and a fifth step of transmitting said partial image, said second signed data and said ciphered signed data to said data reception side; wherein said data reception step comprises: a sixth step of obtaining said partial image, said second signed data and said ciphered signed data, a seventh step of deciphering said obtained ciphered signed data with a secret key of said data reception side so as to obtain third signed data, an eighth step of merging said obtained partial image and said third signed data and applying a one-way function to the merged data, a ninth step of deciphering said received second signed data with a private key of said data transmission side, and a tenth step of comparing results of said eighth and ninth steps so as to verify data validity.