Device and method for authenticating and certifying printed documents

• US 6,567,530 B1
• Filed: 11/23/1998
• Issued: 05/20/2003
• Est. Priority Date: 11/25/1997
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Demetriou, Stamatios, Keronen, Seppo Reino
• Primary Examiner(s): Mehta, Bhavesh
• Assistant Examiner(s): Tabatabai, Abolfazl
• Application Number:
  US09/197,472
• Time in Patent Office: 1,639 Days
• Field of Search: 380/246, 380/51, 380/54, 382/100, 235/380, 399/367
• US Class Current: 382/100
• CPC Class Codes: G09C 5/00 Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages
• CPC Class Codes: H04L 2209/34 Encoding or coding, e.g. Huffman coding or error correction
• CPC Class Codes: H04L 9/3249 using RSA or related signature schemes, e.g. Rabin scheme

Abstract

A certifier device (90) for producing a certified document (101) of an original document (100) and a verifier device (300) for verifying the certified document (101). The certifier device (90) includes a scanner (102) for scanning the original document (100) to generate a true copy image. The certifier has also an encoder (104) for computing a digital code which is representative of the true copy image; an encryptor (108) for encrypting the digital code according to a private key associated with a certifier identification; and a compositor (107) for compositing an image including the true copy image together with the encrypted digital code and certifier identification. The verifier device (300) includes a scanner (301) for scanning the certified document (101); a decryptor (307) for decrypting the encrypted digital code according to a public key associated with the certifier identification; and a encoder (309) for computing a digital code which is representative of the true copy image. The verifier (300) also has a comparator (308) for comparing the digital code supplied by said encoder (309) and said decrypted digital code supplied by said decryptor (307); wherein a match of the digital codes indicates the certified document is authentic and a mismatch indicates the document is not authentic.

Claims

1. A certifier device for producing a certified document of an original document, the certifier device comprising:

a scanner for scanning the original document to generate a true copy image of the original document;

an encoder for computing a digital code from said true copy of the original document in accordance with a two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy image;

an encryption device for encrypting the digital code according to a private key associated with a certifier identification; and

a compositor for compositing an image including the true copy image together with the encrypted digital code and certifier identification.

2. A certifier device as claimed in claim 1, wherein said encoder computes the digital code in accordance with a grey scale.

3. A certifier device as claimed in claim 1, wherein said encryption device computes the encrypted digital code in accordance with a RSA algorithm.

4. A certifier device as claimed in claim 1, wherein the certifier device further comprises a printer for printing the composited true copy image together with the encrypted digital code and certifier identification.

5. The certifier device as claimed in claim 1, wherein the certifier identification includes a certifier identification number.

6. A certifier device as claimed in claim 1, wherein the certifier device further comprises a reduction device for reducing a size of the true copy image of the original document and wherein said encoder computes said digital code using said reduced true copy image.

7. A certifier device as claimed in claim 6, wherein the composited image comprises the reduced true copy image in a first section, the encrypted digital code in a second section and the certifier identification in a third section of the composited image.

8. A certified document comprising;

a true copy image of an original document;

a certifier identification; and

an encrypted digital code, wherein the encrypted digital code is a result of encryption of a digital code by a private key associated with the certifier identification and said digital code is a result of coding said true copy of the original document in accordance with a two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy image.

9. A certified document as claimed in claim 8, wherein the digital code has been coded in accordance with a grey scale.

10. A certified document as claimed in claim 8, wherein the encrypted digital code has been encrypted in accordance with a RSA algorithm.

11. A certified document as claimed in claim 8, wherein the true copy image is a reduced image of the original document.

12. A certified document as claimed in claim 11, wherein the certified document comprises the reduced true copy image in a first section, the encrypted digital code in a second section, and the certifier identification in a third section of the certified document.

13. A verifier device for verifying a certified document, the certified document comprising:

a true copy image of an original document;

a certifier identification; and

an encrypted digital code, wherein the encrypted digital code is a result of encryption of a digital code by a private key associated with the certifier identification and said digital code is a result of coding said true copy of the original document in accordance with a two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy image, the verifier device comprising;

a scanner for scanning the certified document;

a decryption device for decrypting the encrypted digital code according to a public key associated with the certifier identification;

an encoder for computing a digital code from said true copy of the original document in accordance with said two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy images; and

a comparator for comparing the digital code supplied by said encoder and said decrypted digital code supplied by said decryption device,

wherein a match of the digital codes indicates the certified document is authentic and a mismatch indicates the certified document is not authentic, and wherein those parts of the digital codes that do not match indicates those portions of the certified document which are not authentic.

14. A verifier device as claimed in claim 13, wherein said encoder computes the digital code in accordance with a grey scale.

15. A verifier device as claimed in claim 13, wherein said decryption device decrypts the encrypted digital code in accordance with a RSA algorithm.

16. A verifier device as claimed in claim 13, wherein the verifier device further comprises a display for showing where any mismatch between the certified document and the original document may occur.

17. A method of producing a certified document of an original document, said method comprising the steps of:

scanning the original document to generate a true copy image of the original document;

computing a digital code from said true copy of the original document in accordance with a two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy image;

encrypting the digital code according to a private key associated with a certifier identification; and

compositing an image including the true copy image together with the encrypted digital code and the certifier identification.

18. A method of verifying a certified document, the certified document comprising:

a true copy image of an original document;

a certifier identification; and

an encrypted digital code, wherein the digital code is a result of encryption of a digital code by a private key associated with the certifier identification and said digital code is a result of coding said true copy of the original document in accordance with a two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy image, said method comprising the steps of;

scanning the certified document;

decrypting the encrypted digital code according to a public key associated with the certifier identification;

computing a digital code from said true copy of the original document in accordance with said two dimensional error detecting block code, wherein parts of the digital code are associated with corresponding portions of the true copy image; and

comparing said decrypted digital code and said computed digital code,

wherein a match of the digital codes indicates the certified document is authentic and a mismatch indicates the certified document is not authentic, and wherein those parts of the digital codes that do not match indicates those portions of the certified document which are not authentic.