United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,805,702
`
`Curry et al.
`
`[45] Date of Patent:
`
`Sep. 8, 1998
`
`US005805702A
`
`[54] METHOD, APPARATUS, AND SYSTEM FOR
`TRANSFERRING UNITS OF VALUE
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`[75]
`
`Inventors: Stephen M. Curry, Dallas; Donald W.
`Loomis, Coppell; Christopher W. Fox,
`Dallas, all of Tex.
`
`12/1986 White .................................... .. 364/408
`4,630,201
`
`5,077,792 12/1991 Herring ......... ..
`5,577,121
`11/1996 Davis et al.
`............................ .. 380/24
`
`[73] Assignee: Dallas Semiconductor Corporation,
`Dallas, Tex.
`
`[21] Appl. No.: 595,014
`
`[22]
`
`Filed:
`
`Jan. 31, 1996
`
`Related U.S. Application Data
`
`[60]
`
`Provisional application No. 60/004,510, Sep. 29, 1995.
`
`Int. Cl.6 ...................................................... .. H04L 9/00
`[51]
`[52] U.S. Cl.
`.............................................................. .. 380/24
`[58] Field of Search ................................ .. 380/23, 24, 25
`380/30; 364/717, 464.02
`
`Primary Examiner—Thomas H. Tarcza
`Assistant Examiner—Carmen D. White
`
`Attorney, Agent, or Firm—Jenkens & Gilchrist
`
`[57]
`
`ABSTRACT
`
`The present invention relates to an electronic module used
`for secure transactions. More specifically,
`the electronic
`module is capable of passing encrypted information back
`and forth between a service provider’s equipment via a
`secure, encrypted technique so that money and other valu-
`able data can be securely passed electronically. The module
`is capable of being programmed, keeping track of real time,
`recording transactions for later review, and creating encryp-
`tion key pairs.
`
`15 Claims, 8 Drawing Sheets
`
`USER
`
`BANK/SERVICE PROVIDER
`
`F2
`
`
`
`
`
`READ MODULE ID
`
`NUMBER AND AMOUNT
`OF CASH REQUESTED
`
`
`
`
`F1
`
`WANTS TO ADD AN
`
`AMOUNT OF CASH
`TO MODULE
`
`
`
`
`REQUEST MODULE TO
`PRODUCE A RANDOM SALT
`
`
`
`
`
`
`F3
`
`CREATE RANDOM
`SALT NUMBER
`
`
`ID NUMBE
`OMBINE SALT,
`
`AND CASH AMOUNT AND
` F4
`ENCRYPT WITH SERVICE
`PROVIDERS PRIVATE KEY,
`
`THEREBY CREATING A
`SIGNED SERVICE
`PROVIDER CERTIFICATE
`
`
`
`
`
`
`
`DECRYPT SIGNE SERVICE
`PROVIDER CERTIFICATE
`WITH SERVICE PROV|DER'S
`PUBLIC KEY AND CHECK
`TH ID NUMBER AND
`RANDOM SALT NUMBER
`
`
`
`
`
`GROUPON - EXHIBIT 1001
`
`F5
`
`
`
`
`IF THE ID NUMBER AND
`RANDOM SALT NUMBER
`IS UNCHANGED THEN ADD
`HE CASH AMOUNT To TH
`MONEY REGISTER or
`
`THE MODULE
`
`
`
`
`
`
`
`GROUPON - EXHIBIT 1001
`
`

`
`U.S. Patent
`
`Sep.8,1998
`
`Sheet 1 of8
`
`5,805,702
`
`UNIQUE ID NUMBER
`
`MICRO PROCESSOR
`
`CLOCK
`
`10
`
`/1/
`
`14
`
`MATH COPROCESSOR
`
`-
`OUTPUT BUFFER
`
`' INPUT BUFFER
`
`ONE-WIRE
`
`INTERFACE
`
`CONTROL
`
`16
`
`22
`I NVRAM I 20
`
`24
`
`34
`
`ENERGY
`CIRCUITRY
`
`CREATE TRANSACTION GROUP
`
`GENERATE KEYS AND LOAD
`
`INTO A TRANSACTION GROUP
`
`PRIVATIZE DECRYPTION EXPONENT
`
`
`
`CREATE TRANSACTION SCRIPT
`
`LOCK TRANSACTION GROUP
`
`FIG. 2
`
`

`
`U.S. Patent
`
`Sep.8,1998
`
`Sheet 2 of8
`
`5,805,702
`
`USER RECEIVES SECURE E-MAIL
`AND ENCRYPTED IDEA KEY
`
`
`
`MODULE RECEIVES ENCRYPTED
`IDEA KEY IN AN INPUT OBJECT
`OF A TRANSACTION GROUP
`
`
`
`A3
`
`TRANSACTION SCRIPT DECRYPTS
`THE IDEA KEY
`
`DECRYPTED IDEA KEY IS PLACED
`IN AN OUTPUT DATA OBJECT
`
`IDEA KEY IS USED TO DECRYPT
`THE SECURE E-MAIL
`
` A4
`
`
`
`
`
`
`FIG. 3
`
`CREATE TRANSACTION GROUP FOR
`PERFORMING ELECTRONIC
`NOTARY FUNCTIONS
`
`
`
`
`CREATE OBJECT(S) FOR
`RSA ENCRYPTION KEYS
`
`CREATE OBJECT FOR IIMEKEEPING
`
`CREATE TRANSACTION SEQUENCE
`OBJECT (COUNTER)
`
`CREATE A TRANSACTION SCRIPT THAT CREATES A
`CERTIFICATE BY COMBINING AN INPUT DATA OBJECT
`WITH THE TRUE TIME. THE VALUE OF THE TRANSACTION
`COUNTER AND A UNIQUE NUMBER ASSOCIATED TO THE
`MODULE. THEN SIGNS THE CERTIFICATE
`
`
`B5
`
`B6
`
`
`
`
`PRIVATIZE OBJECTS
`
`LOCK TRANSACTION GROUP
`
`
`
`
`

`
`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 3 of 8
`
`5,805,702
`
`MESSAGE IS PLACED IN AN
`INPUT DATA OBJECT
`
`
`
`
`
`
`TRANSACTION SCRIPT COMBINES
`MESSAGE WITH OTHER DATA AND
`SIGNS THE COMBINATION WITH A
`PRIVATE KEY CREATING AN
`ENCRYPTED CERTIFICATE
`
`
`
`FIG. 5
`
`
`
`
`
`THE CERTIFICATE CAN BE READ
`AT A LATER TIME BY ENCRYPTING
`IT WITH THE PUBLIC KEY
`
`
`
`
`THE CERTIFICATE AND ORIGINAL
`DOCUMENT CAN BE
`STORED ELECTRONICALLY
`
`
`
`
`
`C2
`
`C3
`
`C4
`
`
`
`PREPARE MODULE
`
`
`
`CREATE TRANSACTION GROUP
`COMPRISING: MONEY OBJECT
`
`TRANSACTION COUNT OBJECT
`PRIVATE KEY AND
`
`PUBLIC KEY OBJECTS ETC.
`
`
`
`FIG. 6
`
`D2
`
`
`
`D3
`
`D4
`
`D5
`
`
`
`
`
`
`
`RSA ENCRYPTION KEYS
`
`
`
`
`
`

`
`U.S. Patent
`
`Sep.8,1998
`
`Sheet 4 of8
`
`5,805,702
`
`USER
`
`MERCHANT
`
`BANK/SERVICE PROVIDER
`
`E2
`
`E5
`
`E4
`
`E5
`
`E9
`
`E12
`RECEIVE MODULES
`SIGNED CERTIFICATE
`
`DECRYPT MODULES
`ceanncnz WITH sERvICE
`PROV|DER'S PUBLIC KEY
`
`DECRYPT MERCHANT'S
`CERTIFICATE wITH
`MERCHANT's PUBUC KEY
`
`E13
`
`E”
`
`IF BOTH CERTIFICATES
`ARE OK THEN ADD
`PURCHASE AMOUNT TO
`
`MERCHANT'S BANK BALANCE
`
`USER WANTS TO MAKE
`A PURCHASE
`USING A MODULE
`
`.
`REIBSNIIIBEIE”
`
`5‘
`
`
`
`
`CREATE DATA PACKET
`
`THAT INCLUDES A
`'RANDOM SALT’ AND
`
`MODULE ID NUMBER
`
`
`
`CREATE A SIGNED
`
`MERCHANT CERTIFICATE
`
`BY ENCRYPTING DATA
`
`PACKET WITH
`MERCHANT'S PRIVATE KEY
`
`
`
`
`
`E6
`
`
`
`SUBTRACT PURCHASE
`AMOUNT FROM
`MoNEY REGISTER
`
`AITACHES PURCHASE
`PRICE To MERCHANT'S
`SIGNED CERTIFICATE
`
`INCREMENT
`TRANSACTION AMOUNT
`
`E7
`
`COMBINE TRANSACTION
`COUNT WITH MERCHANT's
`5,GNED CERHHCATE
`AND PURCHASE AMOUNT;
`aw-=Twm«
`sERvICE PRovIDER's
`PRIVATE KEY THEREBY
`CREATING A SIGNED
`MODULE CERTIFICATE
`
`INCREMENT
`
`TR"”SA°“°” A”'°”'"
`E11
`
`RECEIVE SIGNED MODULE
`CERTIFICATE AND DECRYPT
`pRoII’§I'Ifs5§Se“I?§ KEY
`
`
`OONFIRM THAT;
`1) AMOUNT OF PURCHASE
`
`
`IS CORRECT
`2) DATA IN MERCHANTS
`
`
`CERTIFICATE IS THE
`
`
`SAME As ORIGINALLY SENT
`E10
`
`FIG. 7
`
`

`
`U.S. Patent
`
`Sep.8,1998
`
`Sheet 5 of8
`
`5,805,702
`
`[ER
`
`BANK/SERVICE PROVIDER
`
`
`
`
`READ MODULE ID
`NUMBER AND AMOUNT
`OF CASH REQUESTED
`
`
`
`WANTS TO ADD AN
`AMOUNT OF CASH
`TO MODULE
`
`
`F2
`
`F4
`
`
`REQUEST MODULE TO
`CREATE RANDOM
`PRODUCE A RANDOM SALT
`
`SALT NUMBER
`
`
`
`OMBINE SALT.
`ID NUMBE
`AND CASH AMOUNT AND
`
`DECRYPT 5|GNE SERVICE
`ENCRYPT WITH SERVICE
`
`PROVIDER CERTIFICATE
`PROVIDER'S PRIVATE KEY,
`
`WITH SERVICE PROV|DER'S
`THEREBY CREATING A
`PUBLIC KEY AND CHECK
`SIGNED SERVICE
`
`TH ID NUMBER AND
`PROVIDER CERTIFICATE
`RANDOM SALT NUMBER
`
`
`
`
`
`F5
`
`IF THE ID NUMBER AND
`RANDOM SALT NUMBER
`Is UNCHANGED THEN ADD
`HE CASH AMOUNT To TH
`MONEY REGISTER or
`THE MODULE
`
`
`
`
`F3
`
`EXAMPLE OF
`TRANSFER FROM USER'S MODULE TO MERCHANT'S MODULE
`
`USER/PAYER
`
`RECEIVE SALT AND
`
`MERCHANT/PAYEE
`
`1. CREATE RANDOM SALT
`REQUEST FOR MONEY
`2. DETERMINE AMOUNT OF
`MONEY TO BE
`RECEIVED FROM PAYER
`
`
`
`
`
`
`
`
`SUBTRACT REQUESTED
`MONEY AMOUNT FROM
`A MONEY REGISTER
`
` CREATE SIGNED PAYMENT
`ERTIFICATE BY COMBININ
`SALT WITH PAYMENT
`
`
`
`
`
`
`RECEIVED SIGNED PAYMENT
`
`CERTIFICATE AND DECRYPT
`PUBLIC KEY
` WITH BANK/SERVICE
`USING SERVICE PROVIDERS
`
`PROVlDER'S PRIVATE KEY
`
`
`G3
`
`G4
`
`
`
`
`PAYEE=MERCHANT
`pAYER=UsER
`CHECK DECRYPTED SALT
`AGAINST ORIGINALLY SENT SALT
`
`IF THEY ARE THE SAME
`ADD PAYMENT AMOUNT
`TO MONEY REGISTER
`
`
`FIG. 9
`
`
`
`
`
`
`
`

`
`U.S. Patent
`
`Sep.8,1998
`
`Sheet 6 of8
`
`5,805,702
`
`TRANSACTION OVER A NETWORK WITH A MODULE
`
`USER/PAYER
`
`MERCHANT/PAYEE
`
`
`RECEIVE PAYER SALT AND
`COMBINE WITH AMOUNT OF
`
`
`
`
`H1
`
`CREATE RANDOM
`PAYER SALT
`
`MONEY TO BE RECEIVED, AND
`INCLUDE A PAYEE SALT, THEN
`ENCRYPT WITH SERVICE
`PRovIDER'S PRIVATE KEY TO
`CREATE A FIRST DATA PACKE'|'
`
`
`
`
`
`
`
`H2
`
`
`
`
`
`
`
`RECEIVE SECOND DATA PACKET
`AND DECRYPT USING SERVICE
`PRoVIDER'S PUBLIC KEY
`
`EXTRACT DECRYPTED PAYEE
`
`SALT AND COMPARE WITH
`PAYEE SALT PROVIDED EARLIER
`
`H6
`
`H7
`
`H3
`
`RECEIVE FIRST DATA PACKET
`AND DECRYPT wITH SERVICE
`PRoVIDER'S PUBLIC KEY
`
`COMPARE ENCRYPTED
`PAYER SALT WITH ORIGINAL
`PAYER SALT
`
`IF THEY ARE THE SAME,
`SUBTRACT AMOUNT OF MONEY
`TO BE SENT FROM
`PAYER To REGISTER
`
`
`
`H4
`
`GENERATE A sECoND DATA
`PACKET CONSISTING or
`PAYEE'S SALT AND THE
`AMOUNT or MONEY T0
`
`BE SENT AND ENCRYPT
`USING SERVICE
`PROV|DER’S PRIVATE KEY
`
`H5
`
`FIG. 10
`
`
`
`IF BOTH ARE THE SAME ADD
`
`MONEY AMOUNT T0
`PAYEE MONEY REGISTER
`
`
`
`
`
`
`

`
`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 7 of 8
`
`COMMAND
`
`LOCKED
`TRANSACTION
`GROUP
`
`READ ONLY OBJECT COMMAND
`
`READ/WRITE OBJECT COMMANDS
`
`TRANSACTION
`GROUP
`
`READ ONLY OBJECT COMMAND
`
`READ/WRITE OBJECT COMMANDS
`
`TRANSACTION
`GROUP
`
`LOCKED
`OBJECTS (L)
`
`

`
`U.S. Patent
`
`Sep.8,1998
`
`Sheet 8 of8
`
`5,805,702
`
`I/O DATA BUFFERS
`
`TRANSACTION GROUP
`
`GROUP NAME,
`PASSWORD AND ATTRIBUTES
`
`OBJECT 1
`
`
`
`SYSTEM DATA
`
`COMMON PIN, RANDOM
`NUMBER REGISTER, ETC...
`
`OUTPUT DATA OBJECT #1
`
`OUTPUT DATA OBJECT #2
`
`WORKING REGISTER
`
`
`
`
`
`OBJECT 2
`
`
`
`OBJECT N
`
`TRANSACTION RECORD
`
`GROUP OBJECT
`ID
`ID
`
`DATE/TIME
`STAMP
`
`
`
`TRANSACTION GROUP 1
`
`TRANSACTION GROUP 2
`
`TRANSACTION GROUP N
`
`AUDIT TRAIL‘
`
`CIRCULAR BUFFER OF
`TRANSACTION RECORDS
`
`‘THE AUDIT TRAIL DOES
`NOT EXIST UNTIL THE
`MICRO—lN—A—CAN
`HAS BEEN LOCKED
`
`THE AUDIT TRAIL
`
`ONCE LOCKED ALL
`UNUSED RAM IS
`ALLOCATED FOR
`
`FIG. 12
`
`

`
`5,805,702
`
`1
`
`METHOD, APPARATUS, AND SYSTEM FOR
`TRANSFERRING UNITS OF VALUE
`
`BACKGROUND OF THE INVENTION
`
`1. Technical Field of the Invention
`
`The present invention relates to a method, apparatus and
`system for transferring money or its equivalent electroni-
`cally. In particular, in an electronic module based system, the
`module can be configured to provide at least secure data
`transfers or to authorize monetary transactions.
`2. Description of Related Art
`Presently, credit cards that have a magnetic strip associ-
`ated with them, are a preferred monetary transaction
`medium in the market place. A card user can take the card
`to an automatic cash machine, a local store or a bank and
`make monetary transactions. In many instances the card is
`used via a telephone interface to make monetary exchanges.
`The magnetic strip card is used to help identify the card and
`user of the card. The card provides a relatively low level of
`security for the transfer. Regardless, the card enables a card
`holder to buy products, pay debts and make monetary
`exchanges between separate bank accounts.
`Improvements have been made to the magnetic strip card.
`There have been cards created with microcircuits instead of
`
`magnetic strips. In general the microcircuit, like a magnetic
`strip, is used to enable a card-reader to perform a transaction.
`SUMMARY OF THE INVENTION
`
`The present invention is an apparatus, system and method
`for communicating encrypted information between a pref-
`erably portable module and a service provider’s equipment.
`The invention comprises a module,
`that has a unique
`identification, that is capable of creating a random number,
`for example, a SALT, and passing the random number, along
`with, for example, a request to exchange money, to a service
`provider’s equipment. The service provider’s equipment
`may in return encrypt the random number with a private or
`public key (depending on the type of transaction), along with
`other information and pass the encrypted information back
`to the module as a signed certificate. The module, upon
`receiving the signed certificate, will decrypt the certificate
`with a public or private key (depending on the type of
`transaction) and compare the decrypted number with the
`original random number. Furthermore, if the numbers are the
`same then the transaction that was requested may be deemed
`secure and thereby proceeds. The module is capable of time
`stamping and storing in memory information about
`the
`transaction for later review.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`A more complete understanding of the method and appa-
`ratus of the present invention may be had by reference to the
`following Detailed Description when taken in conjunction
`with the accompanying Drawings wherein:
`FIG. 1 is a block diagram of an embodiment of a module;
`FIG. 2 is an exemplary process for creating a transaction
`group;
`
`FIG. 3 is an exemplary technique for receiving an E-mail
`message;
`FIG. 4 is an exemplary technique for preparing a module
`for notary functions;
`FIG. 5 is an exemplary technique for using the module as
`a notary;
`FIG. 6 is an exemplary technique for preparing a module
`to perform a money transaction;
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`FIG. 7 is an exemplary technique for performing a money
`transaction using a module;
`FIG. 8 is an exemplary technique for performing a money
`transaction using a module;
`FIG. 9 is an exemplary technique for performing a money
`transaction using a module;
`FIG. 10 is an exemplary technique for passing data over
`a network;
`FIG. 11 is an exemplary organization of the software and
`firmware within a module; and
`FIG. 12 is an exemplary configuration of software and
`firmware within a module.
`
`DETAILED DESCRIPTION OF A PRESENTLY
`PREFERRED EXEMPLARY EMBODIMENT
`
`FIG. 1 depicts a block diagram of an exemplary module
`10 that
`incorporates an exemplary embodiment of the
`present invention. The module circuitry can be a single
`integrated circuit. It is understood that the module 10 could
`also be on multiple integrated or descrete element circuits
`combined combined together. The module 10 comprises a
`microprocessor 12, a real time clock 14, control circuitry 16,
`a math coprocessor 18, memory circuitry 20, input/output
`circuitry 26, and an energy circuit.
`The module 10 could be made small enough to be
`incorporated into a variety of objects including, but not
`limited to a token, a card, a ring, a computer, a wallet, a key
`fob, badge, jewelry, stamp, or practically any object that can
`be grasped and/or articulated by a user of the object.
`The microprocessor 12 is preferably an 8-bit
`microprocessor, but could be 16, 32, 64 or any operable
`number of bits. The clock 14 provides timing for the module
`circuitry. There can also be separate clock circuitry 14 that
`provides a continuously running real time clock.
`The math coprocessor circuitry 18 is designed and used to
`handle very large numbers. In particular, the coprocessor
`will handle the complex mathematics of RSA encryption and
`decryption.
`The memory circuitry 20 may contain both read-only-
`memory and non-volatile random-access-memory.
`Furthermore, one of ordinary skill in the art would under-
`stand that volatile memory, EPROM, SRAM and a variety of
`other types of memory circuitry could be used to create an
`equivalent device.
`Control circuitry 16 provides timing, latching and various
`necessary control functions for the entire circuit.
`An input/output circuit 26 enables bidirectional commu-
`nication with the module 10. The input/output circuitry 26
`preferably comprises at least an output buffer 28 and an
`input buffer. For communication via a one-wire bus, one-
`wire interface circuitry 32 can be included with the input/
`output circuitry 26.
`An energy circuit 34 may be necessary to maintain the
`memory circuitry 20 and/or aid in powering the other
`circuitry in the module 10. The energy circuit 34 could
`consist of a battery, capacitor, R/C circuit, photovoltaic cell,
`or any other equivalent energy producing circuit or means.
`The firmware architecture of a preferred embodiment of a
`secure transaction module and a series of sample applica-
`tions using the module 10 will now be discussed. These
`examples are intended to illustrate a preferred feature set of
`the module 10 and to explain the services that the module
`offers. These applications by no means limit the capabilities
`of the invention, but instead bring to light a sampling of its
`capabilities.
`
`

`
`5,805,702
`
`3
`I. OVERVIEW OF THE PREFERRED MODULE
`AND ITS FIRMWARE DESIGN
`
`The module 10 preferably contains a general-purpose,
`8051-compatible micro controller 12 or a reasonably similar
`product, a continuously running real-time clock 14, a high-
`speed modular exponentiation accelerator for large integers
`(math coprocessor) 18, input and output buffers 28, 30 with
`a one-wire interface 32 for sending and receiving data, 32
`Kbytes of ROM memory 22 with preprogrammed firmware,
`8 Kbytes of NVRAM (non-volatile RAM) 24 for storage of
`critical data, and control circuitry 16 that enables the micro
`controller 12 to be powered up to interpret and act on the
`data placed in an input circuitry 26. The module 10 draws its
`operating power from the one-wire line. The micro control-
`ler 12, clock 14, memory 20, buffers 28, 30, one-wire
`front-end 32, modular exponentiation accelerator 18, and
`control circuitry 16 are preferably integrated on a single
`silicon chip and packaged in a stainless steel microcan using
`packaging techniques which make it virtually impossible to
`probe the data in the NVRAM 24 without destroying the
`data. Initially, most of the NVRAM 24 is available for use
`to support applications such as those described below. One
`of ordinary skill will understand that there are many com-
`parable variations of the module design. For example,
`volatile memory can be used, or an interface other than a
`one-wire could be used. The silicon chip can be packaged in
`credit cards, rings etc.
`The module 10 is preferably intended to be used first by
`a Service Provider who loads the module 10 with data to
`
`enable it to perform useful functions, and second by an End
`User who issues commands to the module 10 to perform
`operations on behalf of the Service Provider for the benefit
`of the End User. For this reason,
`the module 10 offers
`functions to support the Service Provider in setting up the
`module for an intended application. It also offers functions
`to allow the End User to invoke the services offered by the
`Service Provider.
`Each Service Provider can reserve a block of NVRAM
`
`memory to support its services by creating a transaction
`group 40(refer to FIGS. 11 and 12). A transaction group 40
`is simply a set of objects 42 that are defined by the Service
`Provider. These objects 42 include both data objects
`(encryption keys, transaction counts, money amounts, date/
`time stamps, etc.) and transaction scripts 44 which specify
`how to combine the data objects in useful ways. Each
`Service Provider creates his own transaction group 40,
`which is independent of every other transaction group 40.
`Hence, multiple Service Providers can offer different ser-
`vices in the same module 10. The number of independent
`Service Providers that can be supported depends on the
`number and complexity of the objects 42 defined in each
`transaction group 40. Examples of some of the objects 42
`that can be defined within a transaction group 40 are the
`following:
`RSA Modulus Clock Offset
`
`RSA Exponent Random SALT
`Transaction Script Configuration Data
`Transaction Counter Input Data
`Money Register Output Data
`Destructor
`
`Within each transaction group 40 the module 10 will
`initially accept certain commands which have an irreversible
`effect. Once any of these irreversible commands are
`executed in a transaction group 40, they remain in effect
`until the end of the module’s useful life or until the trans-
`
`4
`to which it applies, is deleted from the
`action group 40,
`module 10. In addition, there are certain commands which
`have an irreversible effect until the end of the module’s life
`or until a master erase command is issued to erase the entire
`contents of the module 10. These commands will be dis-
`
`cussed further below. These commands are essential to give
`the Service Provider the necessary control over the opera-
`tions that can be performed by the End User. Examples of
`some of the irreversible commands are:
`
`Privatize Object Lock Object
`Lock Transaction Group Lock Micro-In-A-CanTM
`Since much of the module’s utility centers on its ability to
`keep a secret, the Privatize command is a very important
`irreversible command.
`
`Once the module 10, as a whole, is locked, the remaining
`NVRAM memory 24 is allocated for a circular buffer for
`holding an audit trail of previous transactions. Each of the
`transactions are identified by the number of the transaction
`group, the number of the transaction script 40 within the
`specified group, and the date/time stamp.
`The fundamental concept implemented by the firmware is
`that the Service Provider can store transaction scripts 44 in
`a transaction group 40 to perform only those operations
`among objects that he wishes the End User to be able to
`perform. The Service Provider can also store and privatize
`RSA key or keys (encryption keys) that allow the module 10
`to “sign” transactions on behalf of the Service Provider,
`thereby guaranteeing their authenticity. By privatizing and/
`or locking one or more objects 42 in the transaction group
`40, the Service Provider maintains control over what the
`module 10 is allowed to do on his behalf. The End User
`
`cannot add new transaction scripts 44 and is therefore
`limited to the operations on objects 42 that can be performed
`with the transaction scripts 44 programmed by the Service
`Provider.
`
`II. USAGE MODELS OF THE MODULE
`
`This section presents a series of practical applications of
`the module 10, ranging from the simplest
`to the most
`complex. Each of these applications is described in enough
`detail to make it clear why the module 10 is the central
`enabling technology for that application.
`
`A. BACKGROUND OF SECURE E-MAIL
`
`In this section we provide an example of how a module 10
`could be used to allow anyone to receive his or her own
`e-mail securely at any location.
`1. Standard E-Mail
`
`In a standard e-mail system, a user’s computer is con-
`nected to a provider of Internet services, and the user’s
`computer provides an e-mail password when polling the
`provider’s computer for new mail. The mail resides on the
`provider’s computer in plain text form, where it can be read
`by anyone working there. In addition, while traveling from
`its source, the mail passes through many computers and was
`also exposed at these locations. If the user receives his mail
`from his provider over a local area network, anyone else on
`the same network can capture and read the mail. Finally,
`with many e-mail systems that do not require the user to
`enter the password, anyone sitting at the user’s computer can
`retrieve and read his mail, since his computer automatically
`provides the password when it polls the provider’s com-
`puter.
`It is frequently also possible to copy the password from a
`configuration file in the user’s computer and use it to read his
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`
`5,805,702
`
`5
`mail from a different computer. As a result of this broad
`distribution of the e-mail in plain text form and the weakness
`of password protection, standard e-mail is regarded as very
`insecure.
`
`To counter this problem, the security system known as
`P.G.P. (Pretty Good Privacy) was devised. To use P.G.P., a
`user generates a complete RSA key set containing both a
`public and private component. He makes his public key
`widely available by putting it in the signature block of all his
`e-mail messages and arranging to have it posted in publicly
`accessible directories of P.G.P. public keys. He stores his
`private key on his own personal computer, perhaps in a
`password-protected form. When someone wishes to send
`private e-mail to this user, he generates a random IDEA
`encryption key and encrypts the entire message with the
`IDEA encryption algorithm. He then encrypts the IDEA key
`itself using the public key provided by the intended recipi-
`ent. He e-mails both the message encrypted with IDEA and
`the IDEA key encrypted with the user’s public key to the
`user. No one that sees this transmission can read it except the
`intended recipient because the message is encrypted with
`IDEA and the IDEA key is encrypted with the intended
`recipient’s public key. The recipient’s computer contains the
`corresponding private key, and hence can decrypt the IDEA
`key and use the decrypted IDEA key to decrypt the message.
`This provides security from those who might try to read the
`user’s mail remotely, but it is less effective when the user’s
`computer is accessible to others because the computer, itself,
`contains the private key. Even if the private key is password
`protected, it is often easy to guess the user’s password or
`eavesdrop on him when he enters it, so the user’s computer
`provides little security. In addition,
`the user can receive
`secure e-mail only at his own computer because his private
`key is stored in that computer and is not available elsewhere.
`Therefore, the weakness of P.G.P. is that it is tied strongly to
`the user’s computer where the private key resides.
`2. Module Protected E-Mail
`
`With the exemplary module 10 being used to protect
`e-mail, a user could have his e-mail forwarded to him
`wherever he goes without fear that it would be read by others
`or that his PC would be the weak link that compromises the
`security of his mail. The module protected e-mail system is
`similar to the P.G.P. system, except that the private key used
`for decrypting the IDEA key is stored in a privatized object
`in a transaction group of the module 10 instead of in a PC.
`The module protected e-mail system operates as follows:
`a. Referring to FIGS. 2, 11 and 12, the user creates a
`transaction group 40, S1, generates an RSA key set S2
`and loads it into three objects 42 of the transaction
`group 40 (one RSA modulus object, N, and two RSA
`exponent objects, E and D). He then privatizes the
`decryption exponent S3, D. Finally, he creates a trans-
`action script 44, S4 to take data placed in the input data
`object, encrypt
`it with the modulus N and private
`exponent D and place the result in the output data
`object. He locks the group S5 to prevent any additional
`transaction scripts 44 from being added. He “forgets”
`the value of D and publishes the values of E and N in
`public directories and in the signature blocks of his
`e-mail messages. Since he has forgotten D and since the
`D exponent object has been privatized, there is no way
`that anyone will ever find out the value of D.
`b. Referring to FIG. 3, to send secure e-mail to the user,
`the P.G.P. system is used. When the user receives the
`secure e-mail A1, he transmits the encrypted IDEA key
`into the input data object of the transaction group 40,
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`A2 and then calls the transaction script 44 to decrypt
`this key A3 and place the decrypted result in the output
`data object A4. He then reads the decrypted IDEA key
`from the output data object and uses it to decrypt his
`mail A5. Note that it is now impossible for anyone,
`including the user, to read any new mail without having
`physical possession of the module 10. There is there-
`fore no way that a user’s mail can be read without his
`knowledge, because the module 10 must be physically
`present on the computer where the mail is read. The
`user can carry his module 10 wherever he goes and use
`it
`to read his forwarded mail anywhere. His home
`computer is not the weak point in the security system.
`Secure e-mail, as described above, is the simplest possible
`module application, requiring only one RSA key and one
`transaction script 44. It is unnecessary even to store the
`public key E in the module 10, but it is a good idea to do so
`because the public key is supposed to be publicly accessible.
`By storing E in an exponent object and not privatizing that
`object or the modulus object, N, the user insures that the
`public key can always be read from the module 10. There are
`no transaction scripts 44 involving E because the module 10
`will never be required to perform an encryption.
`B. DIGITAL NOTARY SERVICE
`
`This section describes a preferred notary service using the
`module 10.
`
`1. Background of a Standard Notary Service
`A conventional Notary Service Provider receives and
`examines a document from an End User and then supplies an
`uncounterfeitable mark on the document signifying that the
`document was presented to the notary on a certain date, etc.
`One application of such a notary service could be to record
`disclosures of new inventions so that the priority of the
`invention can later be established in court if necessary. In
`this case, the most important service provided by the notary
`is to certify that the disclosure existed in the possession of
`the inventor on a certain date. (The traditional method for
`establishing priority is the use of a lab notebook in which
`inventors and witnesses sign and date disclosures of signifi-
`cant inventions.)
`2. Electronic Notary Service Using The Module
`A company, hereafter referred to as the Service Provider,
`decides to go into business to supply a notary service
`(strictly, a priority verification service) for its customers,
`hereafter referred to as the End Users. The Service Provider
`
`chooses to do this by using the module 10 as its “agents” and
`gives them the authority to authenticate (date and sign)
`documents on his behalf. The preferred operation of this
`system is as follows:
`a. Referring to FIGS. 4, 11 and 12, the Service Provider
`creates a transaction group 40 for performing electronic
`notary functions in a “registered lot” of modules 10,
`B1.
`
`b. The Service Provider uses a secure computing facility
`to generate an RSA key set and program the set into
`every module 10 as a set of three objects 42, a modulus
`object and two exponent objects B2. The public part of
`the key set is made known as widely as possible, and
`the private part is forgotten completely by the Service
`Provider. The private exponent object is privatized to
`prevent it from being read back from the modules 10.
`c. The Service Provider reads the real-time clock 14 from
`
`each module 10 and creates a clock offset object that
`contains the difference between the reading of the
`real-time clock 14 and some convenient reference time
`
`

`
`5,805,702
`
`7
`
`(e.g., 12:00 a.m. Jan. 1, 1970). The true time can then
`be obtained from any module 10 by adding the value of
`the clock offset object to the real-time clock B3.
`d. The Service Provider creates a transaction sequence
`counter object initialized to zero B4.
`e. The Service Provider creates a transaction script 44
`which appends the contents of the input data object to
`the true time (sum of real-time clock 14 and the value
`of the clock offset object) followed by the value of the
`transaction counter followed by the unique lasered
`registration number. The transaction script 44 then
`specifies that all of this data be encrypted with the
`private key and placed in the output data object. The
`instructions to perform this operation are stored in the
`transaction group 40 as a transaction script object B5.
`f. The Service Provider privatizes any other objects 42
`that
`it does not wish to make directly readable or
`writable B6.
`
`g. The Service Provider locks the transaction group 40,
`preventing any additional transaction scripts 44 from
`being added B7.
`h. Referring to FIG. 5, now the Service Provider distrib-
`utes the modules to paying customers (End Users) to
`use for notary services. Anytime an End User wishes to
`have a document certified, the End User performs the
`Secure Hash Algorithm (Specified in the Secure Hash
`Standard, FIPS Pub. 180) to reduce the entire document
`to a 20 byte message digest. The End User then
`transmits the 20 byte message digest to the input data
`object C1 and calls on the transaction script 44 to bind
`the message digest with the true time,
`transaction
`counter, and unique lasered serial number and to sign
`the resulting packet with the private key C2.
`i. The End User checks the certificate by decrypting it
`with the public key and checking the message digest,
`true time stamp, etc. to make sure they are correct C3.
`The End User then stores this digital certificate along
`with the original copy of the document in digital form
`C4. The Service Provider will attest to the authenticity
`of the certificates produced by its modules.
`j. After a period of time specified by the Service Provider,
`the user returns his module 10, pays a fee, and gets a
`new module containing a new private key. The old
`modules can be recycled by erasing the entire transac-
`tion group and reprogramming them. The Service Pro-
`vider maintains an archive of all the public keys it has
`ever used so that
`it can testify as needed to the
`authenticity of old certificates.
`
`C. DIGITAL CASH DISPENSER
`
`This exemplary usage model focuses on the module 10 as
`a cash reservoir from which payments can be made for
`goods or services. (To simplify the discussion, the subject of
`refilling the module 10 with cash is postponed until later). In
`this case the Service Provider is a bank or other financial
`institution, the End User is the bank’s customer who wishes
`to use the module 10 to make purchases, and the Merchant
`is the provider of the purchased goods or services. The roles
`of the Service Provider, the Merchant, and the End User in
`these transactions are explained in detail below.
`The fundamental concept of the digital cash purse as
`implemented in the module 10 is that the module 10 initially
`contains a locked money object containing a given cash
`value, and the module 10 can generate, on demand, certifi-
`cates which are essentially signed documents attesting to the
`
`8
`fact that the amount of money requested was subtracted
`from the value of the money object. These signed documents
`are equivalent to cash, since they attest to the fact that the
`internal money object was decreased in value by an amount
`corres