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`QC100 .U57 NO.500-157 1988 V19 C.1 NIST-
`
`St.
`(formerly National Bureau of Standards)
`
`NBS
`
`PUBLICATIONS
`
`Computer Science
`and Technology
`
`NIST Special Publication 500-157
`
`Smart Card Technology:
`New Methods for Computer
`Access Control
`
`Martha E. Haykin
`
`Robert B. J. Warnar
`
`IPR2022-00600
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`

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`

`

`Computer Science
`and Technology
`
`iwi
`
`NIST Special Publication 500-157
`
`Smart Card Technology:
`New Methods for Computer
`Access Control
`
`Martha E. Haykin and Robert B. J. Warnar
`
`Security Technology Group
`Institute for Computer Sciences and Technology
`National Institute of Standards and Technology
`Gaithersburg, MD 20899
`
`September 1988
`
`/ w %
`
`NOTE: As of 23 August 1988, the National Bureau of
`Standards (NBS) became the National Institute of
`Standards and Technology (NIST) when President
`Reagan signed Into law the Omnibus Trade and
`Competitiveness Act.
`
`U.S. DEPARTMENT OF COMMERCE
`C. William Verity, Secretary
`
`National Institute of Standards and Technology
`
`(formerly National Bureau of Standards)
`
`Ernest Ambler, Director
`
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`

`

`Reports on Computer Science and Technology
`
`The National Institute of Standards and Technology has a special responsibility within the Federal
`Government for computer science and technology activities. The programs of the NIST Institute for
`Computer Sciences and Technology are designed to provide ADP standards, guidelines, and technical
`advisory services to improve the effectiveness of computer utilization, and to perform appropriate re-
`search and development efforts as foundation for such activities and programs. This publication series will
`report these NIST efforts to the Federal computer community as well as to interested specialists in the
`governmental, academic, and private sectors. Those wishing to receive notices of publications in this
`series should complete and return the form at the end of this publication.
`
`Library of Congress Catalog Card Number: 88-600577
`National Institute of Standards and Technology
`Special Publication 500-157, 52 pages (Sept. 1988)
`CODEN: XNBSAV
`
`U.S. GOVERNMENT PRINTING OFFICE
`WASHINGTON: 1988
`
`For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402
`
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`

`

`CONTENTS
`
`ABSTRACT
`
`1.0 INTRODUCTION
`Overview and Scope of this Document
`1.1
`The Definition of a Smart Card
`Smart Cards and the International Organization
`for Standardization
`Security in a Generalized Smart Card
`
`1.2
`
`1.3
`
`1.4
`
`page
`
`1
`
`1
`
`1
`
`2
`
`2
`
`4
`
`2.0 SMART CARD INTEGRATED CIRCUIT TECHNOLOGIES ... 5
`Integrated Circuits (ICs)
`2.1
`Limitations of IC Technology
`
`5
`
`6
`
`2.2
`
`3.0 THE SMART CARD MICROCOMPUTER
`Single-chip Versus Multiple-chip Smart Card Microcomputers .
`3.1
`The Smart Card Microprocessor
`Smart Card Memories
`Smart Card Input/Output (I/O)
`Contact and Non-contact Smart Card Interfaces
`3.4.1
`The Smart Card Reader/Writer Device
`
`3.2
`3.3
`3.4
`
`3.4.2
`
`6
`
`7
`
`8
`
`8
`
`10
`
`10
`
`13
`
`4.0 OTHER CARD TECHNOLOGIES AND THE
`CURRENT ROLE OF THE SMART CARD
`Storage Card Technologies—Machine- and Human- Readable
`4.1
`Storage Card Technologies—Machine-Readable Only
`
`4.2
`
`Early Approaches
`4.2.1
`4.2.2 The Magnetic Stripe Card
`4.2.3 The Laser- Written Optical Memory Card
`The Integrated Circuit (IC) Storage Card
`4.2.4
`Current Constraints on the Role of the Smart Card
`Factors in the Placement of the Smart Card IC Chip(s)
`4.3.1
`Cost Factors of the Smart Card
`
`4.3.2
`
`4.3
`
`5.0 ACCESS CONTROL AND THE SMART CARD
`Basic Access Control Concepts
`5.1
`Cryptographic Techniques:
`Encryption and Message Authentication
`User Authentication
`Device Authentication
`5.1.3
`The Smart Card and Authentication
`
`5.1.1
`
`5.1.2
`
`5.2
`
`iii
`
`13
`
`. 13
`
`14
`
`14
`
`15
`
`15
`
`16
`
`17
`.... 17
`18
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`18
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`18
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`18
`
`19
`20
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`. 21
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`23
`
`24
`
`26
`
`28
`
`28
`29
`.... 29
`... 31
`31
`
`33
`
`34
`
`34
`
`35
`35
`
`36
`
`. 37
`40
`
`41
`
`43
`
`5.3
`
`5.4
`
`5.5
`
`Smart Card Encryption Capabilities
`Secure Storage: Smart Card Memory Zones
`Smart Card Life Cycle
`
`6.0 NBS ACCESS CONTROL RESEARCH
`6.1 NBS Plastic Memory Key Access Control Systems
`Access Control System for "Dumb" Terminals
`6.1.1
`Access Control System for Cryptographic Workstations
`6.1.2
`The NBS Biometric Smart Card Access Control System
`Future NBS Investigations in Access Control
`
`6.2
`6.3
`
`7.2
`
`7.3
`
`7.4
`
`7.0 FUTURE SMART CARD FORECAST
`Future Smart Card Costs
`7.1
`Future Changes in Smart Card Integrated Circuitry
`The Role of EPROM in Future Smart Cards
`7.2.1
`The Role of EEPROM in Future Smart Cards
`7.2.2
`Expected Changes in the Appearance and Construction
`of the Smart Card
`Expected Changes in Smart Card Operations
`and Applications
`The Role of Standards in the Future of Smart Cards
`
`7.5
`
`APPENDIX: STANDARDS ACTIVITIES
`FOR INTEGRATED CIRCUIT CARDS
`
`REFERENCES
`
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`LIST OF FIGURES
`
`Figure 1: A Generalized Smart Card System
`
`Figure 2: Expected ISO Specifications for Placement
`
`of Contact- Type I/O Connector
`
`Figure 3: Expected ISO Specifications for Functions of Pins
`
`in Contact-Type I/O Interface
`
`Figure 4: Contact-Type Smart Card Interface
`
`Figure 5: Non-Contact- Type Smart Card Interface
`
`Figure 6: A General System of Authentication
`Figure 7: A System of Authentication Using Smart Cards
`
`Figure 8:
`
`Possible Smart Card Memory Zones
`
`Figure 9:
`
`Life Cycle of a Smart Card
`
`Figure 10: Access Control System for Cryptographic Workstations
`
`Figure 11: Biometric Smart Card Access Control System
`Figure 12: Approximate Storage Capacity of Dedicated EPROM Chips
`
`Figure 13: Current Smart Card Characteristics
`
`Figure 14:
`
`Possible Features for Future Smart Cards
`
`Figure Al: ISO IC Card Standards Groups
`
`Figure A2: ANSI IC Card Standards Groups
`
`page
`
`4
`
`11
`
`11
`
`12
`
`12
`
`21
`
`23
`
`25
`
`27
`
`30
`
`32
`
`36
`
`38
`
`39
`
`41
`
`42
`
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`

`ALU
`ANSI
`ATM
`CMOS
`DES
`EEPROM
`EPROM
`FTC
`
`IC
`
`ICC
`
`I/O
`
`ISO
`LAN
`MAC
`NBS (now NIST)
`
`NMOS
`PIN
`PC
`RAM
`ROM
`
`LIST OF ACRONYMS
`
`arithmetic logic unit
`
`American National Standards Institute
`
`automated teller machine
`
`complementary metal-oxide semiconductor
`
`Data Encryption Standard
`
`electrically erasable programmable read-only memory
`
`erasable programmable read-only memory
`
`financial transaction card
`
`integrated circuit
`
`integrated circuit card
`
`input/output
`
`International Organization for Standardization
`
`local area network
`
`message authentication code
`
`National Bureau of Standards
`
`(now National Institute of Standards and Technology)
`
`n-channel metal-oxide semiconductor
`
`personal identification number
`
`personal computer
`
`random access memory
`
`read-only memory
`
`ACKNOWLEDGMENTS
`
`The authors would like to thank the following people for their assistance in the prepa-
`
`ration of this document: Miles Smid, Dennis Gilbert, Dana Grubb, and especially Donna
`
`Fogle Dodson. Ms. Dodson's unfailing support in both the technical and editorial review
`
`of this document was extremely helpful.
`
`vi
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`ABSTRACT
`
`A smart card is a credit-card-sized device containing one or more integrated circuit
`chips, which perform the functions of a microprocessor, memory, and an input/output
`interface. Smart cards, and other related devices, may be used to provide an increased
`level of security in applications requiring controlled access to sensitive information. This
`publication describes the basic components of a smart card, and the goals and obstacles of
`smart card application development. Possible roles for smart cards in modern computer
`security systems and research conducted at the National Bureau of Standards (NBS) in
`the area of smart card access control systems are discussed. A forecast is made for the
`characteristics and applications of future smart cards and related devices. An overview of
`current standards activities for smart cards is given in an appendix.
`
`Key words: Access control; authentication,- biometrics; computer security; cryptography;
`Data Encryption Standard (DES); electrically erasable programmable read only memory
`(EEPROM); erasable programmable read only memory (EPROM); integrated circuit card;
`microcomputer; reader/writer device; smart card; token.
`
`1.0 INTRODUCTION
`
`With microscopic electronic circuits placed inside credit-card-sized plastic carriers,
`smart cards offer the possibility that someday most individuals will carry their own com-
`puters in their pockets. Smart cards may greatly facilitate a wide range of information
`Applied in banking, telephone services, medical records systems,
`processing activities:
`and other areas, smart cards can provide users with both a secure medium for storing
`and carrying personal information and a means for accessing resources in a network of
`computers.
`
`As the use of computers and computer networks has grown to encompass more and
`more of everyday life, the demand for effective computer security strategies has become
`more urgent. Smart cards, which are capable of both securely storing and processing data,
`may play a key role in improving the security of many computer systems.
`
`1.1
`
`Overview and Scope of this Document
`
`This document describes the basic components of a smart card and provides back-
`ground information on the underlying integrated circuit technologies. The capabilities of a
`smart card are discussed, with emphasis on the use of the smart card in computer security
`applications. Research conducted at the National Bureau of Standards (NBS) on smart
`card access control techniques is described. A forecast is made on expected developments
`in smart card technology. The appendix outlines the major U.S. and international groups
`involved in the development of standards for smart cards and related devices.
`
`1
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`This document is intended to provide the reader with a general understanding of the
`use of smart card technology in computer access control. Several factors which must be
`considered in examining the security requirements of a computer system are discussed. It
`should be recognized, however, that smart cards and access control techniques are just one
`part of an overall computer security program. In accordance with the Brooks Act (P.L.
`89-306) and the Computer Security Act of 1987 (P.L. 100-235), NBS develops guidelines,
`technology forecasts, and other documents to provide information on a wide range of com-
`puter security topics. Information about these documents is available in NBS Publications
`List 91, "Computer Security Publications." |NBS 88]
`
`1.2
`
`The Definition of a Smart Card
`
`The term "smart card" has been used as a label for a wide variety of hand-held plastic
`devices containing mechanisms for storing and/or processing information. There is much
`debate over exactly what capabilities and characteristics a device must have in order to be
`considered a smart card. One source states that a smart card is implemented "in a piece
`of plastic the size of a credit card" and that "each smart card contains its own central
`processing unit [which is] essentially a small computer." [MCIV 85, p.
`Another
`152]
`source, with a broader definition, suggests that a smart card "consists of an integrated
`circuit chip or chips packaged in a convenient form to be carried on one's person." [SVGL
`85, p. l] With the latter definition, the category of smart cards includes integrated circuit
`data storage cards and key-shaped devices, which may not have any computational powers.
`Magnetic stripe and optical laser storage cards have also sometimes been referred to as
`smart cards, because they have data storage capacity.
`
`As researchers and manufacturers struggle to develop and distribute products in step
`with the latest technological advances, confusion over the terminology of new devices arises.
`For purposes of discussion, this document will use the following definition of a smart card:
`
`A smart card is a credit-card-sized device containing one or more integrated circuit
`chips, which perform the functions of a microprocessor, memory, and an input/output
`
`interface.
`
`Devices which are not of standard credit card size (i.e., plastic keys and dogtags, or
`cards which are thicker than the standard credit card), but which otherwise conform to
`this definition, will be referred to in this document as "smart tokens."
`
`1.3
`
`Smart Cards and the International Organization
`for Standardization (ISO)
`
`The International Organization for Standardization (ISO) develops voluntary interna-
`tional standards in many scientific, technological, and economic fields. ISO has not defined
`or produced standards for any devices specifically labelled as "smart cards."
`
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`ISO is, however, actively involved in the development of standards for what ISO calls
`an integrated circuit card (ICC). Some of the fundamental characteristics of an ISO ICC
`are:
`
`- The ICC contains one or more integrated circuits.
`
`- The length (3.370 inches), width (2.125 inches), and thickness (0.030 inches) of an
`ICC are the same as the dimensions of a standard credit card.
`
`- The ICC allows spaces on the surface of the card for magnetic stripe and embossed
`data storage, in order to allow compatibility with existing technologies.
`
`(An outline of ISO integrated circuit card standards activities is given in the appendix.)
`Smart cards, as defined in this document, are similar to ISO IC cards except that 1) smart
`cards do not necessarily have magnetic stripe and embossing areas, and 2) smart cards
`must have processing capability. The ability of the smart card to process information, and
`not simply store it, is of vital importance in applications in which the security of sensitive
`information must be maintained. The following section presents a simple example of how
`a smart card system can be used to protect sensititive data.
`
`1.4
`
`Security in a Generalized Smart Card System
`
`A generalized smart card system contains a smart card, a smart card reader/ writer
`device, a terminal, a host computer, and the connections necessary to interface these
`components (see fig. 1).
`
`On a superficial level, a smart card system resembles conventional data storage card
`systems, such as automated teller machine (ATM) systems which use magnetic stripe cards.
`However, because smart cards have computing powers and greater capacity for protected
`data storage, smart card systems can provide increased flexibility and security in many
`applications.
`
`For example, a company that has proprietary information stored in its main computer
`could use a smart card system to maintain and protect this sensitive data in a scenario
`such as the following:
`
`A smart card is issued to each employee who has a need to access the computer
`system. Each employee's card is programmed with unique information, such as a
`personal identification number (PIN). The smart card's microcomputer performs a
`secret one-way transformation* on this PIN, to render it unreadable, and then stores
`the transformed PIN in a secret part of its memory.
`
`* A one-way transformation is a mathematical function which is easy to perform but
`nearly impossible to reverse. That is, given the one-way transformation function / and the
`result of this function R = f{D), it is extremely difficult to determine the input to the
`function D.
`
`3
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`Host Computer
`
`Smart Card
`Reader/Writer
`
`Device
`
`Terminal
`
`Smart Card
`
`Figure 1. A Generalized Smart Card System
`
`To access the computer system, an employee must insert his smart card into a reader/
`writer device and enter his unique PIN via the reader/writer's keyboard. The smart
`card's microcomputer chip then performs the same one-way transformation on the
`entered PIN and compares it with the stored PIN. Because this comparison is done
`completely inside the smart card's microcomputer chip, the employee's PIN is never
`written into the open working memory of the host computer, which might be exposed
`to modification or monitoring by an adversary.
`
`If the smart card determines that the two PINs match, information is exchanged
`between the smart card and the host computer to determine the employee's identity
`and which files within the host the employee is entitled to access. The employee can
`then read and update only those files via a terminal connected to the host computer.
`A log of the employee's actions within the computer system can be maintained within
`the smart card's memories.
`
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`2.0 SMART CARD INTEGRATED CIRCUIT TECHNOLOGIES
`
`The smart card's ability to perform the computations and other functions needed in
`security applications depends on the development of the smart card microcomputer, which,
`in turn, is inherently tied to the progress of integrated circuit technologies. This chapter
`discusses some of the concepts and considerations involved in the production of integrated
`circuits.
`
`2.1
`
`Integrated Circuits (ICs)
`
`Integrated circuits (ICs) are electronic circuits, of varying complexity, which are
`formed on individual chips of silicon (or other semiconductor* material). Computers and
`digital instruments are filled with ICs, which are small and can be designed to quickly
`perform complicated functions.
`
`The capability of an IC depends on the amount of circuitry it contains, a quantity
`often described in terms of transistor density. With current IC technology, close to 400
`transistors can be formed in a space as small as the cross-section of a human hair, which
`is approximately 100 microns (millionths of a meter) in diameter. With this transistor
`density, ICs containing about 50,000 transistors can be produced; transistors are placed
`on an integrated circuit and interconnected with "wires" 1 micron in width. If this "wire"
`width were reduced to half a micron, 1500 transistors could be placed in a 100-micron
`cross-sectional area. Cutting the dimensions in half again would make each transistor the
`size of a large virus. With quarter micron "wire" widths, 4500 transistors could be placed
`It is predicted that the latter capability may be
`in the cross-sectional area of a hair.
`reached by 1995 . [WLSN 85, p. 83]
`
`Some sources believe that with the increases in transistor density, the billion-transistor
`IC will become a definite reality by the year 2000. [COLE 87, p.
`If an estimated
`81]
`200,000 transistors are needed to store and handle one page of text, a billion-transistor
`IC could store several thousand printed pages. Any of these pages could be retrieved in a
`random fashion from such a supercircuit and transmitted between two computers in about
`a second.
`
`It is important to realize, however, that as the density of transistors in ICs increases,
`so does the difficulty of producing ICs that function correctly. If a single transistor in any
`part of an IC fails, the operation of the entire IC chip may be impaired.
`
`Semiconductor is a material in which the conductivity ranges between that of a
`*
`conductor and an insulator. The electrical characteristics of semiconductor material are
`dependent upon small amounts of added impurities, called dopants.
`
`5
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`

`2.2
`
`Limitations of IC Technology
`
`Simply stated, the goal of IC technology is to produce reliable ICs which are reduced in
`size and yet increased in capability. The extent to which this goal can be attained is limited
`by the physical characteristics of the materials used for both the substrate (the foundation
`for the IC) and the actual circuitry to be placed on that substrate. All silicon materials
`used to produce IC substrates have a certain defect density. The IC fabrication engineer
`must work within the limitation that, in a given section of silicon substrate material, there
`will be a certain number of defects.
`If this section is cut into a small number of large
`chips, a high percentage of the chips produced will contain one or more defects. However,
`if the section is cut into a large number of small chips, a much lower percentage of the
`chips produced will contain defects. The chips produced must be both large enough to
`accomodate the circuitry to be placed on them and yet small enough that a reasonable
`yield of usable chips can be produced from each section of silicon substrate.
`
`In order to increase the amount of circuitry which can be placed on a small silicon chip,
`the circuits themselves are made smaller. Much research is devoted to methods for reducing
`linewidth, the amount of space needed by an interconnecting "wire." Some sources predict
`that the conventional method (optical lithography) can be pushed to produce circuits with
`0.1 micron linewidths. This would constitute a 5 to 10 times improvement over current
`capabilities. [COLE 87, p.
`83] The smaller reliable circuitry can be made, the more
`functions each chip can support.
`
`In addition to reducing linewidth, current research efforts are aiming towards the pro-
`duction of application-specific ICs (ASICs), partially customized ICs which are fabricated
`according to standard conventions. The increase in IC functionality, made possible by re-
`duced linewidth and custom fabrication, will be of primary importance in the development
`of microcomputer chips such as those used in smart cards.
`
`3.0 THE SMART CARD MICROCOMPUTER
`
`The word microcomputer is typically used to mean simply a "small" computer. Within
`the category of "small" computers there is a very wide variety of devices, ranging from
`a personal computer (which may be equipped with such peripherals as a monitor, a key-
`board, one or more floppy disk drives, a hard disk, a mouse, a modem, a printer, and/or
`others) down to an IC chip no larger than an eraser on the end of a pencil. Microcomput-
`ers may diff"er greatly in their costs, capabilities, and intended applications. In general,
`however, each microcomputer is comprised of three basic components: a microprocessor
`(for managing information), memory (for storing information), and an input/output (I/O)
`interface (for transmitting and receiving information).
`
`The desktop personal computer is one of the most common types of microcomputer.
`A personal computer may contain dozens of integrated circuits; usually one IC forms
`
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`

`—
`
`the microprocessor, a large number of ICs serve as memory, and a few ICs control the
`input/output interface.
`Because they are so small and because they are designed for
`different applications, smart cards do not contain all of the integrated circuitry that is
`housed within personal computers. Smart cards do, however, contain all three of the basic
`microcomputer components.
`
`Researchers and manufacturers have developed many different designs for the tiny
`microcomputer to be placed in a smart card. A fundamental issue in smart card design
`is whether the microcomputer should be restricted to a single IC chip or distributed over
`several chips.
`
`3.1
`
`Single-Chip Versus Multiple-Chip Smart Card Microcomputers
`
`There are advantages and disadvantages to both the muliple-chip and the single-chip
`smart card. A multiple-chip smart card may be less expensive to produce, since it can
`incorporate several easily-attainable, low-cost IC chips. A single-chip smart card, on the
`other hand, requires a more complex, specialized chip, carefully designed to accomodate
`all the required circuitry for the microprocessor, memory and I/O. [MCIV 85, p.
`155]
`In addition, a multiple-chip smart card may be able to perform more functions and store
`more information than a single-chip smart card. However, including more than one chip
`in a smart card presents some difficult problems.
`
`During the course of its use, a plastic credit-card-sized device is subject to a great deal
`of bending and twisting. To be reliable, a smart card IC chip must be placed in one of the
`few areas of a card where the effects of such stress are minimal. If several chips are to be
`contained in a smart card, some of them may have to be placed in the higher-stress areas
`of the card, where they may be more likely to break and cease to function. The connecting
`"wires" which are needed to link several chips together may be similarly susceptible to
`damage.
`
`In addition to the increased chances of breakage, a multiple-chip smart card may
`present a risk in terms of the security of the information to be stored within the card. It may
`be possible for an adversary to "eavesdrop" on the chip-to-chip connections and extract
`secret data from a multiple-chip smart card. Since it contains no chip-to-chip connections,
`the single-chip smart card is generally considered more reliable and more secure than the
`multiple-chip card. For these reasons, the single-chip smart card is currently preferred for
`many applications.
`
`Although it has some limitations, a single-chip smart card can perform all the functions
`of a microcomputer. The following sections describe the components of a microcomputer
`microprocessor, memory, and input/output— as they may be implemented in a single smart
`card IC chip.
`
`7
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`

`3.2
`
`The Smart Card Microprocessor
`
`The microprocessor is the component which makes a smart card "smart" and distin-
`guishes it from cards designed to simply store data. The microprocessor and its associated
`operating system enables the smart card to "make its own decisions" concerning where
`it will store data in its memories and under what circumstances it will transfer informa-
`tion through its input/output interface. The microprocessor itself consists of three major
`components: the arithmetic logic unit (ALU), the control unit, and the bus.
`
`- The ALU provides the basic logic and arithmetic functions for the microcomputer. It
`also contains small storage spaces, called registers, which are needed for performing
`computations, such as addition or multiplication. The ALU interacts with the memory
`and the input/output in order to coordinate the operations of the microcomputer.
`
`- The control unit assures that the timing of events in the various parts of the micro-
`computer are coordinated.
`
`- The bus provides a link between different parts of the smart card microcomputer.
`There are many possible configurations for the bus, which may be comprised of several
`segments. For example, one segment of the bus may link two registers in the ALU
`together, another may link the input/output interface to the microprocessor, and
`still another may link the microprocessor to the main memory of the smart card.
`In general, smart cards are designed such that the bus does not directly connect
`the input/output to the main memory. The microprocessor may be linked between
`the input/output and the main memory in order to "stand guard" over information
`entering and leaving the memory.,
`
`3.3
`
`Smart Card Memories
`
`A smart card may contain several kinds of memory for storing data and programs.
`Virtually all memories currently used in smart card microcomputers are manufactured from
`semiconductor materials. Semiconductor memories consist of matrices of cells formed by
`transistors to store information. By varying the composition and cell configurations of
`semiconductor materials, memories with differing characteristics can be produced. Four
`types of semiconductor memory used in smart cards are discussed below.
`
`Random Access Memory (RAM) - Smart card RAM is generally manufactured from
`metal-oxide-semiconductor silicon. Any information stored in RAM can be accessed
`in a fixed amount of time regardless of the information's position within the memory.
`Access time to information in RAM is in the range of tens to hundreds of nanoseconds
`(billionths of a second). Smart card RAM is usually volatile in nature (that is, it will
`lose its stored information immediately if power to the memory is removed). RAM,
`the fastest type of memory, is often used as a "scratch pad," buffer, or other type of
`temporary storage.
`
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`Read Only Memory (ROM) - Smart card ROM is a semiconductor memory which is
`nonvolatile (i.e., its stored information is retained indefinitely without a continuous
`power supply to the memory). Smart card ROM is typically made from a section
`of semiconductor material in which a series of memory cells have been permanently
`burned or fused, in a particular pattern which forms the underlying structure for a pro-
`gram. In this programming process, which is completed at the ROM manufacturer's
`plant, the ROM is often masked in such a way that it cannot be read or altered by
`the user. Semiconductor ROM is typically used for storing the smart card's general
`operating system programs |MCIV 85, p. 154] (such as the program needed to start
`the smart card when its power is turned on).
`
`Erasable Programmable Read Only Memory (EPROM) - Smart card EPROM is a
`nonvolatile semiconductor memory which can be initially programmed at the user's
`facility rather than at the ROM manufacturer's plant. Data and programs can be
`loaded into the smart card EPROM via a smart card reader/writer device; the trans-
`fer of information is controlled by the smart card's microprocessor. When it is used
`in other types of computers, EPROM can be erased (by exposure to ultraviolet light)
`and reprogrammed. However, EPROM that is used in smart cards is typically manu-
`factured in such a way that it is permanently shielded and cannot be erased or altered.
`This shielding is intended to increase the security of the smart card, by preventing
`unauthorized modification of data stored in the EPROM.* EPROM may be used in a
`smart card to permanently store an audit trail, a complete history of the operation of
`the card. EPROM provides much greater storage density than other memories such
`as EEPROM (see below). However, because data can only be appended to and not
`erased from smart card EPROM, it may eventually become full, and thus the smart
`card will "expire."
`
`Electrically Erasable Programmable Read Only Memory (EEPROM) - Smart card
`EEPROM is a nonvolatile semiconductor memory which can be electrically erased
`and reprogrammed via a reader/writer device at the user's facility. EEPROM can
`be used for storing programs and data which may need to be modified periodically.
`Since EEPROM can be erased, a smart card containing EEPROM will not "expire"
`because its memory is filled up. Currently, however, EEPROM memories have less
`storage capacity, require larger circuitry, and cost more than other types of memory.
`In addition, EEPROM may not be appropriate for storing an audit trail.
`
`A smart card microcomputer chip usually contains both RAM and ROM, for the
`card's temporary working memory and for the operating system programs, and either
`EPROM or EEPROM as a large storage memory area. Using current techniques. EPROM
`and EEPROM cannot be placed together on the same IC chip.
`Thus, for single-chip
`smart cards, either EPROM or EEPROM must be chosen, depending on the intended
`
`* While it may be possible to produce a smart card which contains erasable EPROM.
`it is generally not considered practical, due to packaging difficulties and other limitations
`of erasable EPROM.
`
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`application for the smart card. (Currently, few single-chip smart cards contain EEPROM.)
`In order to utilize both EPROM and EEPROM memories, some maYiufacturers place
`separate EEPROM chips in the smart card together with a microcomputer chip containing
`EPROM. It remains to be seen whether this endeavor is as reliable, secure, and cost-
`effective as the single-chip approach.
`
`3.4
`
`Smart Card Input/Output (I/O)
`
`In order to communicate with the "outside world" of other computers, a smart card
`must have components to perform input/output (I/O) functions. Typically, a smart card
`has some logic circuitry which, in conjunction with the microprocessor, controls the timing
`and flow of data transferred into and out of the smart card's memories. A smart card must
`have some type of physical structure through which it can interface to a reader/writer
`device, which can be connected to other computers for the exchange of data. There are
`two general categories of physical interfaces for smart cards: the contact type and the
`non-contact (or contactless) type.
`
`3.4.1
`
`Contact and Non-contact Smart Card Interfaces
`
`Many smart cards in production today are equipped with contact-type interfaces.
`Typically, this interface consists of an 8-contact connector, which looks like a small gold
`circle or series of squares on the surface of the card. The International Organization
`for Standardization (ISO) is currently developing an international standard for such an
`interface, which may be used in ISO integrated circuit cards (ICCs) or in smart cards. It
`is expected that the ISO standard wil