DS1425 DS1425 Multi iButton FEATURES PACKAGE OUTLINE • Provides a unique 64–bit serial number and three 384 bit fields of password protected RAM • Intelligent response generator included • No external power required TM • Uses inexpensive 1–Wire protocol • Universally portable across platforms 16mm DESCRIPTION Authorization iButtons are sophisticated microelectron- Each Dallas iButton is uniquely serialized with a 64–bit ics, sealed into miniature stainless steel cans, creating a code that is laser–etched in the silicon. This unique ID low cost, portable medium for storing and controlling provides a basic level of security, is traceable in the field, access to sensitive information. and makes it possible to identify the specific iButton in a field of many. iButtons are used with port adapters as a hardware based protection system for software. iButtons help The serial number is divided into three parts (see Figure protect the right to copy software by actually protecting 1). The 8–bit family code tells the Access System (and the right to execute it. Software can now be locked to a consequently the developer) what type of iButton is user, a machine, or an application with a complete audit being used. The next 48 bits are lasered sequentially trail and guaranteed uniqueness. with no two numbers the same. The last 8 bits contain a Cyclic Redundancy Check (CRC) value that has been The DS1425 provides a 64–bit unique ID number, and calculated across the family code and the 48–bit serial three 384 bit fields of password protected RAM. The number. The CRC ensures that iButton communication DS1425 is used to provide nested levels of protection, is error free. or to protect multiple applications. High levels of security are achieved by storing applica- Hardware communication with the iButtons is con- tion code and/or data necessary for execution in the ducted via a 1–Wire interface. The conversion from a iButton memory. PC I/O port to the 1–Wire interface is the responsibility of the port adapter. Each 384–bit secure data area is prefaced by a 64–bit identification field and an unreadable 64–bit password. Software applications communicate with the iButton Note that this password is user selected and pro- using Dallas’ Access System, which is contained in any grammed. This means no one, including Dallas Semi- of the port adapter Developer’s kits. The Access Sys- conductor, can access that data. tem provides easy to use commands which are embedded into the application in order to utilize the iButton resources during run time. 021798 1/2 DS1425 If the DS1425 is presented with a valid password from By using seemingly random data in both the password the host application, the contents of the secure data will and secure data fields, and by generating many false be returned. However, if the DS1425 is presented with accesses for each valid access, even sophisticated an invalid password, the on–board intelligent response attackers are defeated. generator will return what seems to be a normal response, but is not. The false response will be unique to the false access. DS1425 MULTI iButton ORGANIZATION Figure 1 FAMILY CODE 82H 8-BIT CRC CODE 48-BIT SERIAL NUMBER 10000010 Scratchpad 512 bits ID 0 64 bits Password 0 64 bits Secure Data 0 Secure 384 bits Key 0 ID 1 64 bits Password 1 64 bits Secure Secure Data 1 384 bits Key 1 ID 2 64 bits Password 2 64 bits Secure Secure Data 2 Key 2 384 bits 021798 2/2