(12) United States Patent
`Teppler
`
`USOO6792536B1
`US 6,792,536 B1
`Sep. 14, 2004
`
`(10) Patent No.:
`(45) Date of Patent:
`
`(54) SMART CARD SYSTEM AND METHODS
`FOR PROVING DATES IN DIGITAL FILES
`
`(75) Inventor: Steven W. Teppler, Washington, DC
`(US)
`(73) Assignee: TimeCertain LLC, Washington, DC
`(US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(*) Notice:
`
`(21) Appl. No.: 09/421,279
`(22) Filed:
`Oct. 20, 1999
`(51) Int. Cl. .................................................. H04L 9/00
`(52) U.S. Cl. ...............
`... 713/178; 713/415; 713/201
`(58) Field of Search ................................. 713/178, 175,
`713/207; 705/44
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,001,752 A 3/1991 Fischer
`5,022,080 A 6/1991. Durst et al.
`5,136,643 A 8/1992 Fischer
`5,136,646 A 8/1992 Haber et al.
`5,136,647 A 8/1992 Haber et al.
`5,189,700 A
`2/1993 Blandford
`5,373,561 A 12/1994 Haber et al.
`RE34,954 E
`5/1995 Haber et al.
`5,422953 A 6/1995 Fischer
`5,500.897 A 3/1996 Hartman, Jr.
`5,619,571 A 4/1997 Sandstrom et al.
`5,748,738 A 5/1998 Bisbee et al.
`5,781,629 A 7/1998 Haber et al.
`5,781,630 A 7/1998 Huber et al.
`5,903,882 A * 5/1999 Asay et al. ................... 705/44
`5,910,988 A
`6/1999 Ballard
`5,923,763 A 7/1999 Walker et al.
`5,970,146 A 10/1999 McCall et al.
`6,047.282 A 4/2000 Wilson et al.
`6,081.899 A
`6/2000 Byrd
`6,209,090 B1
`3/2001 Aisenberg et al.
`6,209,091 B1 * 3/2001 Sudia et al. ................ 713/175
`6,226,744 B1 * 5/2001 Murphy et al. ............. 713/200
`
`6,237,096 B1 *
`6.253,331 B1
`6,263.438 B1
`6,356,937 B1
`6,393,126 B1
`6,393,566 B1
`6,408,388 B1
`6,442,691 B1
`6,449.255 B1
`6,490,355 B1
`6,530,023 B1
`6,601,172 B1
`2001/0011350 A1
`
`5/2001 Bisbee et al. ............... 713/178
`6/2001 Kotami
`7/2001 Walker et al.
`3/2002 Montville et al.
`5/2002 van der Kaay et al.
`5/2002 Levine
`6/2002 Fischer
`8/2002 Blandford
`9/2002 Waclawsky
`12/2002 Epstein
`3/2003 Nissl et al.
`7/2003 Epstein
`8/2001 Zabetian
`
`FOREIGN PATENT DOCUMENTS
`
`GB
`
`2323455 A 9/1998
`
`OTHER PUBLICATIONS
`D. Mills, “Simple Network Time Protocol (SNTP) Version
`4 for IPva, IPv6, and OSI, Oct. 1996.
`* cited by examiner
`Primary Examiner Kim Vu
`Assistant Examiner Thanhnga B. Truong
`(74) Attorney, Agent, or Firm-Venable LLP, James R.
`Burdett; W. Russell Swindell
`(57)
`ABSTRACT
`A Smart card System and methods for proving dates of digital
`data files includes a trusted time Source, a first Subsystem for
`Saving the file at a moment in time, a Second Subsystem for
`retrieving from the trusted time Source a date and a time
`corresponding to the moment in time, a third Subsystem for
`appending the date and the time retrieved from the trusted
`time Source to the Saved file, a fourth Subsystem for Signing
`the saved file with the date and the time retrieved from the
`trusted time Source appended thereto, a fifth Subsystem for
`hashing the signed file to produce a digest, a sixth Subsystem
`for Signing the digest with a key to produce a certificate, a
`Seventh Subsystem for appending the certificate to the Saved
`file, and an eighth Subsystem for Saving the file with the
`certificate appended thereto. All of the Subsystems are
`preferably Sealed together within a Smart card.
`
`20 Claims, 10 Drawing Sheets
`
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`
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`560 N.
`
`
`
`
`
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`
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`SECONDAPPENDING MEANS
`
`SAVING MEANS
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 1 of 10
`
`US 6,792,536 B1
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`- - - - - - - - - - - - - - - - - - - - - - - - - - -
`
`
`
`
`
`30\/SSEW
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`
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 2 of 10
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`US 6,792,536 B1
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`OZZ
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`
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`
`
`- - - - - - - - - - - - - a -sh - a - - e - r - is
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`39WSSEW
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 3 of 10
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`US 6,792,536 B1
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 4 of 10
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`US 6,792,536 B1
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`
`
`
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`
`
`O)
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`400 \-
`
`SIGNED
`DATA
`FILE
`
`420
`
`is
`
`N
`st
`
`ass
`
`N480
`
`FIG. 4
`PRIOR ART
`
`
`
`520
`
`500-N-
`
`COMPUTING
`MEANS
`
`VERIFICATION
`MEANS
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`
`
`FRAUD
`PREVENTION
`MEANS
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`
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`
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`54 O
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`F.G. 5
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet S of 10
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`US 6,792,536 B1
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`560-N-
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`TRUSTEDLOCAL TIME SOURCE
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`RETREVING MEANS
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`FIRST APPENDING MEANS
`
`FIRST SIGNING MEANS
`
`HASHING MEANS
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`SECOND SIGNING MEANS
`
`
`
`
`
`60
`
`62O
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`630
`
`640
`
`650
`
`660
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`670
`
`690
`
`--730
`
`FIG. 6
`
`FIG. 7
`PRIOR ART
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 6 of 10
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`US 6,792,536 B1
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`TIMECERTAIN
`
`FIG. 8
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`
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`BATTERY
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`TRUSTED
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 7 of 10
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`US 6,792,536 B1
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 8 of 10
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`US 6,792,536 B1
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`SMARTCARD.AWAREAPPLICATION
`
`1260
`
`
`
`SERVICE PROVIDER
`
`1240
`
`SMART CARD RESOURCEMANAGER
`
`FD
`HANDLER
`
`1230
`
`FD
`HANDLER
`
`1230
`
`FD
`HANDLER
`
`1230
`
`
`
`1210 || WIRELESS N1220
`SMART
`CARD
`
`800
`
`1000
`
`SMART
`CARD
`
`1210
`
`SMART
`CARD
`
`800
`
`FIG. 12
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 9 of 10
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`US 6,792,536 B1
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`e - a a
`
`a s - - - a w
`
`as a
`
`v
`
`v
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`sr
`
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`
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`r
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`
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`ICC-AWARE
`APPLICATION
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`SERVICE
`REQUESTS
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`
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`
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`
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`ICC APPLICATION
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`: 1335
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`1340
`
`
`
`
`
`
`
`
`
`
`
`ICC SERVICE
`PROVIDER
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`ISO 7813
`APDU
`
`
`
`ECCOPERATING
`SYSTEM
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`1325
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`-1305
`1310
`
`1330
`
`INTERFACEDEVICE
`(FD)
`
`
`
`DATAEXCHANGE
`CONTROLLED BY
`ISO 7813
`PROTOCOL
`
`
`
`
`
`
`
`
`
`
`
`ICC COMMUNICATION
`CONTROLLER
`
`v
`
`roy an an up ou wa dih
`
`a
`
`us
`
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`
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`
`up
`
`w up up was go up a up up up a la p we no
`
`1315
`
`
`
`1320
`
`FIG. 13
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`1420
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`U.S. Patent
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`Sep. 14, 2004
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`Sheet 10 0f 10
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`US 6,792,536 B1
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`1
`SMART CARD SYSTEM AND METHODS
`FOR PROVING DATES IN DIGITAL FILES
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`This application claims the benefit of U.S. Provisional
`Application No. 60/142,132, filed on Jul. 2, 1999. This
`application is related to the following co-pending, com
`monly assigned applications: U.S. patent application Ser.
`No. 09/649,646, entitled 'METHOD AND SYSTEM FOR
`DETERMINING AND MAINTAINING TRUST IN DIGI
`TAL DATAFILES WITH CERTIFIABLE TIME,” filed Jul.
`3, 2000; U.S. patent application Ser. No. 09/429,360,
`entitled “PERSONAL COMPUTER SYSTEM AND
`15
`METHODS FOR PROVING DATES IN DIGITAL DATA
`FILES,” filed Oct. 28, 1999; and U.S. patent application Ser.
`No. 09/609,645, entitled “METHOD AND SYSTEM FOR
`DETERMINING AND MAINTAINING TRUST IN DIGI
`TAL IMAGE FILES WITH CERTIFIABLE TIME,” filed
`Jul. 3, 2000.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates generally to digital data
`files, and more particularly to a Smart card System and
`methods for proving dates in Such digital data files.
`2. Statement of the Prior Art
`
`25
`
`Scope of the Problem
`Digital data files come in many formats. None of those
`formats currently provide means for proving-with
`certainty-dates and times associated with access, creation,
`modification, receipt, or transmission of Such digital data
`files. This is not only due to the variety of application
`programs which are available for digital data file access,
`creation, modification, receipt, and transmission, but also
`due to the much more varied “Standards' and protocols put
`forth in the vain attempt to provide uniformity worldwide.
`Illustrative of the enormity of the problem are the fol
`lowing operating environments, within which the System
`and methods according to the present invention can provide
`the much-needed but often ignored time certainty.
`Digital Document Processing
`“Processing” may be viewed as the manipulation of data
`within a computer System. Since virtually all computer
`Systems today process digital data, processing is the Vital
`Step between receiving the data in binary format (i.e., input),
`and producing results (i.e., output)—the task for which
`computers are designed.
`The Microsoft(R) press Computer Dictionary, 3d Edition
`(1997) defines the term document as “...any self-contained
`piece of work created with an application program and, if
`Saved on disk, given a unique filename by which it can be
`retrieved.” Most people think of documents as material done
`by word processors alone. To the typical computer, however,
`data is little more than a collection of characters. Therefore,
`a database, a graphic, or a spreadsheet can all be considered
`as much a document as is a letter or a report. In the
`Macintosh environment in particular, a document is any
`user-created work named and Saved as a separate file.
`Accordingly, for the purpose of the invention described
`herein, digital document processing Shall be interpreted to
`mean the manipulation of digital (i.e., binary) data within a
`
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`computer System to create or modify any Self-contained
`piece of work with an application program and, if Saved on
`a disk or any other memory means, given a unique filename
`by which it can be retrieved. Examples of Such application
`programs with which the present invention may be used to
`assist in Such digital document processing are: MicroSoft(R)
`Access 97, Microsoft(R) Excel 97, and Microsoft(R) Word 97,
`each available from Microsoft Corporation, Redmond,
`Wash. U.S.A.
`
`Digital Communications
`“Communications” may be broadly defined as the vast
`discipline encompassing the methods, mechanisms, and
`media involved in information transfer. In computer-related
`areas, communications usually involve data transfer from
`one computer to another through a communications
`medium, Such as a telephone, microwave relay, Satellite link,
`or physical cable.
`Two primary methods of digital communications among
`computers presently exist. One method temporarily connects
`two computers through a Switched network, Such as the
`public telephone System. The other method permanently or
`Semi-permanently linkS multiple workStations or computers
`in a network. In reality, neither method is distinguishable
`from the other, because a computer can be equipped with a
`modem, which is often used to access both privately owned
`and public access network computers.
`More particular forms of digital communications (i.e.,
`eXchange of communications in which all of the information
`is transmitted in binary-encoded, digital format) include
`electronic mail (or less formally "e-mail'), facsimile,
`Voicemail, and multimedia communications.
`E-mail may be broadly defined as the exchange of text
`messageS/computer files over a communications network,
`Such as a local area network (LAN) or the Internet, usually
`between computers or terminals. Facsimile (or, again, less
`formally “fax”) comprises the transmission and reception of
`text or graphics over telephone lines in digitized form.
`Conventional fax machines Scan an original document,
`transmit an image of the document as a bit map, and
`reproduce the received image on a printer. Resolution and
`encoding of Such fax messages are Standardized in the
`CCITT Groups 1-4 recommendations. Fax images can like
`wise be sent and received by computers equipped with fax
`hardware and Software.
`The CCITT Groups 1-4 recommendations make up a set
`of standards recommended by the Comité Consultatif Inter
`national Télégraphique et Téléphonique (now known as the
`International Telecommunication Union) for encoding and
`transmitting images over fax machines. GroupS 1 and 2
`relate to analog devices, which are generally out of use.
`Groups 3 and 4 deal with digital devices, and are outlined
`below.
`Group 3 is a widespread Standard that Supports "standard”
`images of 203 horizontal dots per inch (dpi) by 98 vertical
`dpi, and “fine” images of 203 horizontal dpi by 198 vertical
`dpi. Group 3 devices Support two methods of data compres
`Sion. One is based on the Huffman code, and reduces an
`image to 10 to 20 percent of the original. The other, known
`as "READ" (for “relative element address designate”), com
`presses an image to about six to twelve percent (-6%–12%)
`of its original. Additionally, the READ method provides for
`password protection as well as polling, So that a receiving
`machine can request transmission as appropriate.
`Group 4 is a newer Standard, which Supports images of up
`to 400 dpi. Its method of data compression is based on a
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`3
`beginning row of white pixels, or "dots”, with each Suc
`ceeding line encoded as a Series of changes from the line
`before. Images are compressed to about three to ten percent
`(~3%-10) of the original. Group 4 devices do not include
`error-correction information in their transmission.
`Moreover, they require an Integrated Services Digital Net
`work (ISDN) phone line rather than a traditional dial-up line.
`FaX modems may also be used to Send and receive digital
`data encoded in known fax formats (e.g., one of the CCITT
`groups noted above). Such data is either sent or received by
`a fax machine or another modem, which then decodes the
`data and converts it to an image. If the data was initially sent
`by fax modem, the image must previously have been
`encoded on the computer hosting Such fax modem. Text and
`graphic documents can be converted into fax format by
`special software that is usually provided with the fax
`modem. Paper documents must first be Scanned in. AS is well
`known, fax modems may be internal or external and may
`combine fax and conventional modem capabilities.
`Voicemail generally comprises a System that records and
`Stores telephone messages in a computer's memory. Unlike
`a simple answering machine, Voicemail Systems include
`Separate mailboxes for multiple users, each of whom can
`copy, Store, or redistribute messages. Another type of digital
`communications involving voice is “voice messaging”, a
`term which generally refers to a System that sends and
`receives messages in the form of Sound recordings. Typical
`Voice messaging Systems may employ “voice modems',
`which are modulation/demodulation devices that Support a
`Switch to facilitate changes between telephony and data
`transmission modes. Such a device might contain a built-in
`loudspeaker and microphone for Voice communication, but
`more often it uses the computer's Sound card.
`Still another form of digital communications includes
`multimedia communications in the Style of “Video
`teleconferencing, as defined by the International Telecom
`munication Union (formerly CCITT) in “Visual Telephone
`Systems and Equipment for Local Area Networks Which
`provide a Non-Guaranteed Quality of Service,”
`(Recommendation H.323, Telecommunication Standardiza
`tion Sector of ITU, Geneva, Switzerland, May 1996) and
`other Similar Such Standards.
`Digital Imaging
`“Digital imaging encompasses those known processes
`involved in the capture, Storage, display, and printing of
`graphical images. They may involve devices known as a
`“digital camera', which broadly refers to a camera that
`Stores photographed images electronically instead of on
`traditional film. Digital cameras typically use charge
`coupled device (CCD) elements to capture the image
`through the lens when the operator releases the shutter in the
`camera. Circuits within the camera cause the image captured
`by the CCD to be Stored in a Storage medium, Such as
`Solid-State memory or a hard disk. After the image has been
`captured, it is downloaded by cable to the computer using
`Software Supplied with the camera. Once Stored in the
`computer, the image can be manipulated and processed
`much like the image from a Scanner or related input devices.
`Digital cameras come in the form of Still cameras and
`full-motion video recorders.
`Other forms of digital imaging include digitizing Systems,
`such as the “PhotoCD(R” system from Eastman Kodak
`Company, Rochester, N.Y. That system allows 35 mm film
`pictures, negatives, slides, and Scanned images to be stored
`on a compact disc. Images are then Stored in a file format
`
`4
`known as the Kodak PhotoCD Image pac File Format, or
`PCD. Many photography and film development businesses
`offer this service. Any computer with CD-ROM capabilities
`can usually view images stored on a PhotoCD and the
`Software required to read PCD. Additionally, Such images
`can be viewed by any one of a variety of players that are
`Specifically designed to display images Stored on CDs.
`Another photographic form of digital imaging is defined by
`the “Flashpix” specification, the cooperative endeavor of the
`Digital Imaging Group, MicroSoft, the Hewlett-packard
`Company, and Live picture, Inc. The Flashpix format builds
`on the best features of existing formats (e.g., Kodak Image
`pac, Live picture IVUE, Hewlett-packard JPEG, TIFF, TIFF/
`EP, etc.), and combines these features with an object orien
`tated approach.
`Still other forms of digital imaging include digital
`radiography, radiotherapy, X-ray, positron emission
`tomography, ultrasound, and magnetic resonance imaging
`according to the joint work of the American College of
`Radiology (ACR) and the National Electrical Manufacturers
`Association (NEMA), published in the Digital Imaging and
`Communications in Medicine PS 3-1998 (DICOM
`Standard).
`
`Digital Commerce
`An enormous amount of commercial activity now takes
`place by means of connected computers. Such commercial
`activity has been variously coined as digital commerce,
`electronic commerce, or just plain E-commerce. Regardless
`of its particular moniker, these activities generically involve
`a commercial transaction between a user and a Vendor
`through an online information Service, the Internet, or a
`BBS, or between vendor and customer computers through a
`Specialized form of E-commerce known as electronic data
`interchange (EDI).
`EDI is collectively known for its set of standards to
`control the transfer of business documents (e.g., purchase
`orders and invoices) between computers. The ultimate goal
`of EDI is the elimination of paperwork and increased
`response time. For EDI to be most effective, users must
`agree on certain Standards for formatting and exchanging
`information, such as the X.400 protocol and CCITT X
`SCCS.
`Other known forms of E-commerce include digital
`banking, Web-front Stores, and online trading of bonds,
`equities, and other Securities. Digital banking can take the
`form of access to a user's account, payment of bills
`electronically, or transfer of funds between a user's
`accounts. Web-front Stores (e.g., amazon.com) usually com
`prise a collection of web pages in the form of an electronic
`catalog, which offers any number of products for Sale. More
`often than not, transactions at Such web-front Stores are
`consummated when a purchaser enters his credit card
`number, and the issuing bank approves the purchase. These
`transactions may or may not be over Secure lines, Such as
`those designated “TRUSTe' participant web sites. Further
`details regarding known processes for establishing and
`maintaining Secure E-commerce connections may be found
`in the SET Secure Electronic Transaction Specification,
`Book 1: Business Description (Version 1.0), May 31, 1997,
`the contents of which are incorporated herein by reference.
`See also Book 2 (Programmer's Guide) and Book 3 (Formal
`Protocol Definition) of the SET Secure Electronic Transac
`tion Specification, as well as the External Interface Guide to
`SET Secure Electronic Transaction, Sep. 24, 1997, each of
`which is incorporated herein by reference.
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`US 6,792,536 B1
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`S
`One burgeoning form of E-commerce that has arisen in
`the past few years is that which involves dealing in Securities
`online. “Day traders” watch impatiently as ticker symbols
`Speed across their computer Screens. When the price is right,
`they electronically whisk their order off to a distant securi
`ties dealer-often buying and Selling the same Stock or bond
`in a fifteen-minute Span of time. One can only imagine the
`potential problems associated with the purchase or Sale of
`Securities when price-per-share movements on the order of
`a few cents make the difference to these day traders.
`Fortunately, the National Association of Securities Dealers
`(NASD) has come up with its Order Audit Trail Systems
`(OATS) to track all stock transactions. NASD Rule 6953
`also requires all member firms that have an obligation to
`record order, transaction, or related data under the NASD
`15
`Rules or Bylaws to Synchronize the business clocks that are
`used for recording the date and time of any market event.
`Computer System and mechanical clocks must be Synchro
`nized every business day before market open, at a minimum,
`in order to ensure that recorded order event timestamps are
`accurate.
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`6
`Internet appliances, wireleSS telephones, pagers, PDAS, fax
`machines, digital Still/video cameras, digital Voice/video
`recorders, digital copierS/Scanners, interactive television,
`hybrid combinations of any of the above-noted computing
`means and an interactive television (e.g., Set-top boxes), and
`any other apparatus, which generally comprises a processor,
`memory, the capability to receive input, and the capability to
`generate Output.
`Such computing means typically include a real time clock
`(“RTC) for keeping track of the time and date. Likewise,
`operating Systems and/or applications programs used in Such
`computing means usually stamp the time and date (as
`derived from the RTC) that each of the digital data files is
`accessed, created, modified, received, or transmitted. Such
`Stamping of digital data files with times and dates
`(collectively referred to as "time-Stamping') has, thus,
`become an integral part of all of the above known computing
`environments.
`Although the existing framework of time-Stamping can be
`used to catalogue and Sort one's own files, for other critical
`needs it suffers from two fatal flaws. Files are typically
`“time-stamped” with a value read from the RTC. There is no
`simple way of determining whether the RTC is set to the
`correct date and time. Indeed, it is quite trivial for a user to
`reset the RTC to any desirable date and time. Even if the
`computing means RTC had been correctly Set, nothing
`would prevent a user from arbitrarily changing the "time
`Stamps' themselves. This is readily accomplished through
`the direct manipulation of the digital data where the time
`Stamp is Stored.
`Thus, the known time-stamping framework is useless for
`any situation where the accuracy of the date or time of a
`digital data file is critical. Court filings, medical records,
`files presented as incriminating or exculpatory evidence in
`court cases, legal documents Such as wills, billing records,
`patent, trademark, and copyright claims, and insurance
`documents are only a few of the areas where the date and
`time that is associated with the file is critical. Conventional
`Systems and methods that time-Stamp digital data files fail to
`meet this need. Furthermore, there is no “open”, croSS
`platform, interoperable global Standard in place to create
`trusted time-Stamps.
`Cryptographic Systems and KeyS
`One approach that has been used in the past to provide
`Some level of Security in digital data files is the use of
`cryptographic Systems and keys. In general, cryptographic
`Systems are used to encrypt or “lock” a digital data file. A
`key is used, conversely, to decrypt or “unlock an encrypted
`digital data file. Digital data files are merely bits of data in
`memory or on a network. If this data is viewed as the mere
`representation of large numbers, then mathematical func
`tions or algorithms can be easily applied to the data.
`For example, where a particular digital data file is a text
`file, its unencrypted or “cleartext' version can be viewed as
`the variable X. The resulting function of this variable X, when
`encrypted by its associated cryptographic algorithm and
`coupled with its key k will be f(k, x). Accordingly, the
`encrypted text or “cyphertext' can be defined by the equa
`tion:
`
`By choosing the cryptographic algorithm carefully-Such
`that there is no easily discovered inverse mapping (i.e., for
`any given y, it will be extremely difficult to calculate X
`without knowing k, while at the same time, with knowledge
`of k it will be possible)-the data may be encrypted.
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`Digital Justice
`Even legal Scholars and Systems around the World have
`been unable to escape the problems of an online world. Utah
`became the first jurisdiction in the United States of America
`to enact legislation creating “cybernotaries'. Similar laws in
`Georgia, Florida, and Massachusetts quickly followed Utah.
`In August 1996, the American Bar Association (through
`its Information Security Committee of the Electronic Com
`merce and Information Technology Division, Section of
`Science and Technology) published the Digital Signature
`Guidelines-Legal Infrastructure for Certification Authori
`ties and Secure Electronic Commerce. The European Union,
`35
`as well, in a final report on the Legal Issues Of Evidence And
`Liability In The provision Of Trusted Services (CA and TTP
`Services), let its position be known in October 1998.
`Each of the environments noted above is fraught with
`potential fraud. Any reliance they may have on dates and
`times is merely for the purpose of determining whether the
`transaction is valid (i.e., authorized within a specified range
`of time), or what specific time delays occur in the transmis
`Sion of data between the computer Systems communicating
`with one another. However, none of those environments
`currently provide means for proving with certainty-dates
`and times associated with access, creation, modification,
`receipt, or transmission of digital data files, which may be
`used therein.
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`Prior Art Attempts to Solve the Problem
`Many-varied computing means pervade today's Society.
`PCS, web browsers, e-mail clients, e-mail Servers, network
`file Servers, network messaging Servers, mainframes, Inter
`net appliances, wireleSS telephones, pagers, PDAS, fax
`machines, fax modems, digital Still cameras, Video cameras,
`Voice recorders, Video recorders, copiers, and Scanners, and
`Virtually any other device using digital data files are fast
`becoming ubiquitous.
`Digital data is easy to modify. As a result, it has been
`nearly impossible in the prior art to establish with certainty
`the date and time a particular digital data file in a given
`computing means was accessed, created, modified, received,
`or transmitted. It should be understood that, by use of the
`term “computing means', the present invention is directed to
`general purpose computers, PCS, web browsers, e-mail
`clients/servers, network file/messaging Servers, mainframes,
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`Samsung Ex. 1031, Page 14 of 33
`Samsung Electronics America, Inc. v. RFCyber Corp.
`IPR2021-00980
`
`

`

`7
`Symmetric Cryptography
`If the key for encryption and decryption is the same
`shared Secret, then the cryptographic System and associated
`algorithm will be referred to as “symmetric'. Both the
`Sender and the receiver must share the key in Such symmet
`ric cryptographic Systems. A Sender first applies the encryp
`tion function using the key to the cleartext to produce the
`cyphertext, which is then Sent to a receiver. The receiver
`applies the decryption function using the same shared key.
`Since the cleartext cannot be derived from the cyphertext
`without knowledge of the key, the cyphertext can be sent
`over public networkS Such as the Internet.
`The current United States standard for symmetric
`cryptography, in which the same key is used for both
`encryption and decryption, is the Data Encryption Standard
`(DES), which is based upon a combination and permutation
`of shifts and exclusive orS. This approach can be very fast,
`whether implemented directly on hardware (e.g., 1 GByte/
`Sec throughput or better) or in general purpose processors.
`The current key size of 56 bits (plus 8 parity bits) is
`Sufficient, yet Somewhat Small, but the growing use of larger
`keys with “triple DES' generate much greater Security.
`Since the implementation of DES is fast, it can easily be
`pipelined with Software codecs and not impact System
`performance.
`An alternative and yet stronger form of Symmetric block
`encryption is IDEA. Its Security is based upon combining
`exclusive orS with addition and multiplication in modulo-16
`arithmetic. The IDEA approach is also fast on general
`purpose processors. It is comparable in Speed to known DES
`implementations. One major advantage of IDEA is its keys,
`which are 128 bits and are, thus, much stronger (i.e., harder
`to break) than standard 56-bit DES keys.
`One particular problem with the use of Such Symmetric
`Systems is the problem of getting the Sender and the receiver
`to agree on the key without anyone else finding out.
`Moreover, the problem becomes greatly complicated when
`additional users (i.e., potential Senders and receivers) are
`added to the System. Such Symmetric cryptographic Systems,
`nevertheless, are by far easier to implement and deploy than
`their asymmetric counterparts Since they require far leSS
`infrastructure. Sometimes with a symmetric cryptographic
`System, however, keys are Submitted over the network.
`Avoidance of this security risk would be desirable.
`Asymmetric Cryptography
`Systems that generate and employ a Secure key pair (i.e.,
`a “private key for creating the “digital Signature' and a
`"public key to verify that digital signature) are typically
`known as asymmetric cryptographic Systems. There are
`many known cryptographic algorithms (e.g., RSA, DSA,
`and Diffie Hellman) that involve a key pair. In such asym
`metric cryptographic Systems, the private key and the public
`key are mathematically linked. Anything that is encrypted
`by the public key can only be decrypted by the private key.
`Conversely, anything that is signed by the private key can
`only be verified by the public key. Asymmetric crypto
`graphic Systems are, thus, inherently more Secure than
`Symmetric or shared Secret Systems. The Sensitive private
`key need exist in only one place. No form of the private key
`is ever transmitted over the network. Typical asymmetric
`cryptographic Systems also Scale to many users more easily
`than Shared Secret Systems. However, the infrastructure that
`is necessary to field Systems of this type, commonly called
`a “public Key Infrastructure” (PKI), is non-trivial to imple
`ment. See, e.g., RFC 1422, Privacy Enhancement for Inter
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`US 6,792,536 B1
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`8
`net Electronic Mail: Part II: Certificate-Based Key Man
`agement (February 1996), the contents of which are
`incorporated herein by reference.
`Digital Signatures
`Referring now to FIGS. 1 and 2, wherein like reference
`characters or numbers represent like or corresponding parts
`throughout each of the Several views, an exemplary process
`100 for creating a digital signature is shown in FIG. 1. To
`Sign a document, or for that matter any other digital data file,
`a “signer” must first delimit the borders of the digital data
`file to be signed. AS used herein, the term Signer refers to any
`person who creates a digital Signature for a message, Such as
`message 110. The information delimited by the signer, in
`turn, refers to that message 110. A hash function 120 in the
`signer's Software is used to compute a hash result 130,
`which is unique for all practical pur