Implementing Electronic Card Payment Systems (Artech House Computer Security Series)

4.1 Organization of the EMV ¢ specifications

This section presents the set of documents (Book 1 to Book 4) that form the specification known as the EMV 2000 ”Integrated Circuit Card Specification for Payment Systems [1 “4]. This set of documents replaces the set of documents referred to as the EMV'96 ”Integrated Circuit Card (Terminal, Application) Specification for Payment Systems [5 “7]. The EMV'96 was effective until December 2000 and served as the technical reference for implementations performed before this date. For the reader who is already familiar with the documents comprising the EMV'96 , we provide a mapping of their content into the new set of documents that form the EMV 2000 .

For a better understanding of the documents composing the EMV 2000 specification, the reader is referred to Figure 4.1. In this figure we outline the generic EMV ¢ communication protocol stack, which describes the interaction between the ICC and the terminal and between the terminal and the AH. We also show the user interfaces of the terminal towards the cardholder and the attendant.

Figure 4.1: The EMV ¢ protocol stack and its mapping to EMV 2000 .

The EMV 2000 consists of the following documents:

Book 1: Application Independent ICC to Terminal Interface Requirements [1]. This document is divided into two parts :

• Part I ”Electromechanical Characteristics, Logical Interface, and Transmission Protocols . This part contains the specification of the communication subsystem of the ICC and of the terminal, referred to in Figure 4.1 as the CSS-ICC and CSS Terminal (ICC side), respectively. It describes the electromechanical interface between the ICC and the terminal, specifying both the mechanical and electrical characteristics of the ICC and of the terminal. It also describes the answer-to-reset (ATR) of the card, the physical transportation of characters , the transmission protocols T = 0 and T = 1, and the description of a card session. This part of the specification is a reconsideration of Part I (with the same title) of the EMV'96 ”Integrated Circuit Card Specification for Payment Systems [5]. This part of the specification is said to be application independent since it presents a layer beneath the application layer. Often people refer to this part of the specification as the EMV Level 1. It is important to mention that the communication subsystem between the ICC and the terminal is not analyzed in this book.

• Part II ”Files, Commands, and Application Selection . This part contains the specification of the EMV ¢ application selection mechanism and of the data structures, files, and commands needed for implementing this mechanism. The EMV ¢ application selection mechanism allows a terminal to select an application that claims to be EMV ¢ compliant in a multiapplication ICC. Such an application conforms to the EMV ¢ specification only from the point of view of the selection mechanism. Otherwise, the selected application can implement payment protocols other than the EMV ¢ credit/debit (e.g., an electronic purse conforming to CEPS [8], or a proprietary electronic purse scheme). For this reason this part of the specification is also labeled as application independent, even though it specifies data structures, files, and commands at the application level of the EMV ¢ protocol stack. This part of Book 1 is a reconsideration of the EMV ¢ application selection mechanism from "Part III ”Application Selection" of the EMV '96 ”Integrated Circuit Card Specification for Payment Systems [5]. Concerning the data structures, files, and commands used for application selection, these were previously presented in "Part II ”Data Elements and Commands" of the same EMV'96 ”Integrated Circuit Card Specification for Payment Systems [5].

Book 2: Security and Key Management [2]. This document presents a detailed specification of the security mechanisms in the ICC and terminal:

• SDA and dynamic data authentication (DDA) based on digital signatures. The principles of these mechanisms are explained in Appendix D, Sections D.6.2 and D.7.2, respectively.

• PIN encipherment. This mechanism is outlined in Appendix D, Section D.5.5.

• Secure messaging for integrity and authentication. This mechanism is presented in Appendix D, Section D.2.2. The session key is obtained through a key derivation algorithm, whose principle is explained in Appendix E, Section E.5.

• Secure messaging for confidentiality. We present this mechanism in Appendix D, Section D.1.1.

The topics mentioned above are reconsidered from "Part IV ”Security Aspects" of the EMV'96 ”Integrated Circuit Card Specification for Payment Systems [5].

Certification Authority Public Key Management Principles and Policies is a new topic introduced in EMV 2000, Book 2 . The topic Terminal Security and Key Management Requirements can also be considered as newly introduced in EMV 2000, Book 2 . We make this statement since the terminal security was just briefly mentioned in "Section 4 ”Security Requirements", in Part I ”General Requirements of the EMV'96 ”Integrated Circuit Card Terminal Specification for Payment Systems [6].

Book 3: Application Specification [3] This document is divided into two parts:

• Part I ”Data Elements and Commands . This contains the data structures, files, and commands needed for the implementation of the financial transaction interchange that describes an EMV ¢ debit and credit payment application. The material in this part reconsiders "Part II ”Data Elements and Commands", of the EMV'96 ”Integrated Circuit Card Specification for Payment Systems [5].

• Part II ”Debit and Credit Application Specification . This contains the specification of the financial transaction interchange that describes an EMV ¢ debit and credit payment application. This interchange is characterized by a transaction flow, obtained through the chaining of transaction processing functions (e.g., initiate application processing, read application data, off-line data authentication, etc.). The material in this part reconsiders the EMV'96 ”Integrated Circuit Card Application Specification for Payment Systems [7].

Book 4: Cardholder, Attendant, and Acquirer Interface Requirements [4] This document reconsiders the content of the EMV ¢ '96 ”Integrated Circuit Card Terminal Specification for Payment Systems [6]. It is divided into three parts:

• Part I ”General Requirements . This part contains the acceptable terminal types and their capabilities, the generic functional requirements of the terminal, and its physical characteristics.

• Part II ”Software Architecture . This part presents the software architecture of an EMV ¢ terminal as well as the software and data management procedures that are needed.

• Part III ”Cardholder, Attendant, and Acquirer Interface . This contains the specification of the functionality needed by the man-machine interface to interact with the terminal attendant and cardholder. The interface between the terminal and the AH is also presented in this part.