Cryptography – By modifying optical image
Reexamination Certificate
2000-10-16
2003-08-26
Smithers, Matthew (Department: 2134)
Cryptography
By modifying optical image
C713S176000, C705S064000
Reexamination Certificate
active
06611598
ABSTRACT:
FIELD OF THE INVENTION
This disclosure provides means and methods for self-authentication of value documents which can be produced on and digitally signed by various printing methods or by conventional laser printers.
BACKGROUND OF THE INVENTION
The subject involved herein is about the authentication of the validity of important and valuable documents such as personal checks, commercial checks, traveler checks, credit cards, event tickets, passports driver's licenses, motor vehicle titles and certain negotiable instruments. There is a great impetus to reduce fraud, that is to say, to prevent counterfeits and forgeries which are often elements of existing fraudulent use of the types of documents listed above. Counterfeit documents can be produced by criminals who copy or scan a legitimate check to extract the bank data, signature data, and account data and then produce checks which, for all practical purposes, look identical to the genuinely issued documents. An altered check or even other types of altered documents may use a genuine check or a genuine document, but where the payee, or the amount of the check that is to be paid, is altered, and presents difficulty of detection. It is also possible that stolen check stock may be utilized in order to forge checks where the payee, the amount and signature is fraudulently imprinted.
In order to provide a higher level of security and to detect fraudulent documents, it is most desirable to provide a machine readable authentication or verification method in order to eliminate the problem of the merchant or the bank teller not being properly trained in the art of document security analysis. Also to counteract the threat of espionage, the machine readable authentication techniques must not rely on the secrecy of certain algorithms, or the wide distribution of secret decryption/encryption keys, or on the access to special inks or compounds which are often used to mark the paper.
Public key encryption, and more specifically, public key digital signatures provide a very high level of security which is not available through the previously known algorithms and the decryption/encryption keys or special inks. Easy access to the machine readable data on a: check is made because that data is contained in a 2-D bar-coded symbol in clear text. This is typical of negotiable checks and often used in other valuable documents. However, that particular data (2-D bar-coded symbols in clear text) is highly protected against alteration because that data is used along with the MICR (Magnetic Ink Character Recognition) code line data to produce a digital signature using the private key of thee person who owns the particular account or who digitally signed the document.
Successful authentication by use of the certified public key of the account holder insures that not one bit of the data, which is digitally signed, has been altered, as well as that the person who did the digital signing is the person who he says he is.
An additional level of document security, above that of pure digital signature authentication, is provided by the use of a unique or random pattern provided by a taggant which is permanently applied to the document wherein the pattern code is also included in the clear text and then digitally signed along with the other signed data.
Access to the public key may be provided by a trusted third party who acts as the certificate authority and who encrypts each of the public keys using their own private key. The verification process then uses the public key of the certificate authority in order to expose the required public key of the account holder thereby guarding against any fraudulent keys getting to be used.
CORPORATE CHECK PRINTING: The printing and issue of checks by corporations and small businesses is now primarily done with the use of laser printers. These laser printers use any one of the following two methods.
I. The first method uses blank check stock without any MICR printing in the specific location called the MICR print band. The blank check stock usually contains human visual security features which allow detection of attempted alterations or counterfeiting, although because of the ready availability of basic check stock, the use of it is no guarantee of the validity of the check. MICR provides for bank automation using magnetic ink and utilizes a special font called E-13B. Printing of MICR requires that the laser printer system contain a special font and also a custom magnetic toner cartridge, in order, to print checks that comply with the ANSI magnetic signal level requirements for the E-13B characters and symbols. When printing the MICR code line, the entire customized printing of the issued check is printed using MICR ink. The customized printing usually includes the issuing firm's name and its bank logos, in addition to the check serial number, the payee name, the date, the amount in words, the convenience amount (written in numbers) and optionally, the issuing authority's signature. When the signature facsimile is not printed by the laser printer, then the checks must be manually signed.
II. The second method of printing and issuing checks by corporations and small business uses pre-printed MICR check stock. Each check provided by the check printer is serialized, and the MICR code line is completely printed with the required account number and bank codes required for bank processing. Here the checks are provided on sheets in accordance with a specific accounting application to be used. With this method, the laser printer prints the variable information on the check as was done in the first method, but here is using an ordinary laser printer with standard toner. This method cannot print MICR characters because the toner usually does not contain the required magnetic components necessary to meet the magnetic signal level requirements. Theses type of preprinted checks are usually more expensive than using blank check stock. Additionally, more care is required in keeping the preprinted check stock in a safe place because if stolen, they can easily be used to write fradulent checks.
SUMMARY OF THE INVENTION
In order to enhance the method and means of authenticating data contained in valuable documents such as checks, deeds, passports, negotiable instruments or other authoritative documents, there are now provided enhanced code symbols and elements in addition to the public key based digital signature which can now more properly authenticate the data contained in the document and also can verify the authorship of the digital signer of the document. Thus in order to provide additional encoded information for authentication which would permit the detection of any alteration of the payee's name or the amount involved in the document, the data which is signed is to be made available in machine readable form either from the MICR code line or else contained in a bar code symbol along with its digital signature itself. A laser printer is useful here in printing a two-dimensional (2-D) bar code that can easily contain, upwards of up to 360 8-bit ASCII characters per square inch of label.
Also as part of the system, it is capable of utilizing a code with a moderate amount of in-built error correction that will allow for error recovery and data integrity. Here it is possible to use a security level
2
that provides for recovery from up to 6 unreadable or missed-coded code-words within the 2-D symbol. This level of data integrity is easily feasible without adding significant overhead to the bar code.
The present invention provides an organization of data that is contained in the laser printed 2-D symbol that includes the type and version number, a mandatory license identification field, a mandatory public key identifier, a mandatory check (or document) digital signing date, a optional numerical amount (such as a check amount), an optional name of the payee, an optional identification ID field, an optional magnetic tag data which includes an estimate of the track speed when the taggant symbol was first read, and a mandato
Rasmussen David S.
Rode Lise A.
Smithers Matthew
Starr Mark T.
Unisys Corporation
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