Previous Table of Contents Next


CHAPTER 9
SMART CARDS AND SECURITY

One of the primary reasons smart cards exist is security. The card itself provides a computing platform on which information can be stored securely and on which computations can be performed securely. The smart card is also highly portable and convenient to carry. Consequently, the smart card is ideally suited to function as a token through which the security of other systems can be enhanced.

In financial systems, sensitive information such as bank account numbers can be stored on a smart card. In electronic purse applications (cash cards and the like), the balance of some negotiable currency can even be stored on a card. This currency can be credited or debited by external terminals (systems) in a local transaction.

In physical access systems (such as opening the door to your office), a smart card can hold the key through which an electronic system can be enticed to unlock the door and allow entry. In network systems, or even local computer systems, the smart card can hold the password through which a user is identified to the network or local system and privileges are granted by those systems to access information or processing capabilities.

When viewed in the abstract, all these seemingly disjointed systems have very similar needs and operational characteristics, particularly with regard to the security of those systems. This chapter examines some of the general characteristics of systems that are referred to as security.


Note:  
The term security is often used in a rather loose fashion to refer to a variety of characteristics related to the performance of transactions between two or more parties in such a manner that everyone involved in the transaction trusts the integrity and, perhaps, the privacy of the transaction. With the advent of computer networks and of highly distributed financial transactions, it is often the case that all the necessary parties to a transaction cannot be physically at the same place, or even at the same time, in order to participate in the transaction.

Consider the purchase of an item with a credit card at an airport gift shop while on a trip. This transaction includes a number of distinct steps:

1.  Presentation of the consumer’s credit card to the vendor.
2.  Validation by the vendor that the cardholder is really the owner of the card.
3.  Validation by the vendor that the credit card account represented by the card is valid.
4.  Validation by the vendor that the account maintains a sufficient credit balance to cover the cost of the item being purchased.
5.  Debiting the credit account represented by the card by the amount of the item purchased.
6.  Crediting the account of the vendor with the amount of the item purchased (less any fees due to the bank, and so on related to the credit card transaction).

In the performance of this transaction, the cardholder would also like some assurances that much, if not all, of the information related to the transaction is held private. The credit card name, account number, and validation code should not be obtained by some unscrupulous character bent on making fraudulent purchases with the purloined information.

In the performance of a credit card transaction, there are actually many more components than are mentioned previously. However, in just the steps noted, you can see that physical separation of the various parties to the transaction makes it difficult to guarantee that all these parties are satisfied with the integrity and privacy of the transaction.

This chapter discusses the characteristics of security involved in supporting such a transaction. To facilitate this discussion, the objectives of a security environment are first presented in somewhat abstract terms. Then, some of the elements (we’ll call them players) of a widely distributed transaction system are examined. Some of the mechanisms currently in wide use to provide the desired characteristics through the identified players are examined. Finally, some of the attacks used to thwart these security mechanisms are reviewed.

Objectives and Characteristics of Security Systems

Security within physical or electronic systems can be viewed as the provision of one or more general characteristics:

  Authentication
  Authorization
  Privacy
  Integrity
  Nonrepudiation

When part or all of these characteristics are provided to the extent required to satisfy all the participants of the transaction, the transaction can be considered secure.


Previous Table of Contents Next