Chapter 9
Key Architecture
9.1Overview
This chapter is extracted from the document NAR System & Security Application (SSA) Software Architecture, Key Architecture section, revision 1.19.
Figure 4 on page 75 provides an overview of the Ingenico 6500’s key architecture. A default key is used for the highest level, Sponsor Key KTK (Key Transfer Key). Customers can change the sponsor key. Figure 4 shows the sponsor key under the terminal ID because the sponsor key is unique per terminal.
All keys indicated are loaded by the financial institution or authorized injection facility. The cryptographic keys must be injected into the i6500 terminal in a Key Secure Room. The KTK is the only key that can be transported in the clear between the Key Injection Utility and the device. The rest of the keys may be generated randomly, entered in the system as cryptograms, or entered by key parts using principles of both split knowledge and dual control.
Use a key injection utility, such as Ingenico’s WinKeyFac software program, to perform these functions and to set security options (see Security Options on page 77).
Financial keys (Master/Session and DUKPT) can be based on an application or a terminal. By default, all financial keys are based on an application, as shown in Figure 4. By changing the value of the Financial Key security option (see section 9.5.9 Financial Key Option on page 99), you can make all financial keys based on a terminal; however, this will erase all previously injected financial keys.
Some keys are segregated by application. The application number is part of the application name. Once the keys are injected, the application number is used as the application reference. When the application calls a cryptographic function, it passes the application reference as the application name. The SSA will check that the caller passes the application name, and from the name, it will determine the number that defines the injected key set.
Single-length DES keys have a length of 8 bytes. Double-length triple DES keys have a length of 16 bytes. The level of the specific key set indicates the position of the key set in the internal key hierarchy. For example, keys at Level 1 (sponsor keys) are loaded in clear text and sit at the top of the key hierarchy. Keys at Level 2 are loaded encrypted under the keys at Level 1. Keys at Level 3 are loaded encrypted under the keys at Level 2. Loading a key at a higher level will cause the erasure of all the related lower level keys. The following sections describe each key.
92 | Chapter 9 Key Architecture |
| Section 9.1 Overview |
