Smart Card Systems Short Survey
RD2P

This page is published to provide basic items, references and links to access the smart card technologies and concepts. This survey focuses on dedicated hardware proposed by manufacturers, on embedded operating system whether there are open source or proprietary. It is designed to be the more exhaustive sources as possible for all these points. Nevertheless send an email to deville@lifl.fr or grimaud@lifl.fr to relate some interesting missing references.

Summary :

I. Dedicated Hardware

I.1 - Microprocessors ;
I.2 - Memories ;
I.3 - I/O ;
I.4 - Hardware& devices links.

II. Smart card Operating Systems & basics software

II.1 - Smart card software history ;
II.2 - Current OS status ;
II.3 - Software examples ;
II.4 - Software (open source) links.

III. Usual smart card soft wares

III.1 - Minimalist pieces of software for smart cards ;
III.2 - Conventional "ISO7816-like" operating system architectures ;
III.3 - ;

I. Dedicated Hardware

Dedicated Hardware Smart card industry is known for not publishing detailed information about chipsets they use in their products. This choice is driven by security issues (as well industrial concurrency). Initially, public informations were limited to frequency bus size and memories footprint. Todays chipset manufacturers publish the coreship data sheets. Nevertheless SmartCard manufacturers buy customized version of their microcontrolers. The Figure 1 shows physical connectors and a core view of a typical smartcard microcontroler.

Figure 1: SmartCard connector (left) and microcontroler (right).

Microprocessors :

A wide class of microprocessors are used from old 8-bit CISC micro chip (4.44 Mhz) to powerful 32-bit RISC (100 to 200 Mhz). The type of CPU used for smart card is highly influenced by the ISO[9] constraints linked to the card. For example, as the card is a portable device that is stored in a wallet, it must meet standards related to torsion and bending capacity. Table 1 gives an overview of some processors commonly used in smart cards. Historically, smart card manufacturers used 8-bit processors because operating systems and applications code are known to be more compact. But smart cards now need to be more efficient and new embedded applications require more and more computing power. So card designers now choose 32-bit RISC processors (or 8/16 bits CISC).

Model Architecture Bus Size Registers Frequency
68H05 CISC 8 bits 2 (8 bits) 4,77 Mhz
80xx51 CISC 8 bits 6 (8/16 bits) 4,77 Mhz
AVR AT90 RISC/CISC 8 bits 32 (8/16 bits)

4,77 Mhz -

44,7 Mhz
ARM7xx
ARM9xx		 RISC 32 bits 16 (32 bits) 4,77 Mhz -
30 Mhz
R4KSC RISC 32 bits 32 (32 bits) 4,77 Mhz -
100 Mhz

Table 1: Characteristics of common smart card microprocessors.

Computing performance of a smart card is not a significant problem for operating systems and applications. Cryptographic co-processor usually solve specific smart card computing needs. What is really the limiting factor is the very small amount of memory, and some annoying hardware-specific problems.

Memories :

Different types of memory exist on the card. The first one is the RAM (Random Access Memory); there is also some ROM (Read Only Memory); and finally EEPROM (Electric Erasable Programmable Read Only Memory) or FLASHRAM that are writable persistent memories. Because smart card silicon is supposed to be limited to 20 mm², the physical space needed for storing 1 bit is an important factor. Each kind of memories used is of different size concerning this point; the smallest is the ROM. Table 2 gives an overview of the amount of memory present on board, and also present the ``memory cell'' which is the size for 1 byte of memory on the micro module.

Type memory point usual capacity write time page size
ROM reference 32-128 KB read only bus size
FlashRAM x 2 ~ 3 16-64 KB 2.5 ms 64-1024 bytes
EEPROM x 4 4-64 KB 4 ms 2-64 bytes
RAM x 20 128-4096 B bus bandwith bus size

FeRAM
M-RAM
not published in a Smart Card Product

Table 2: Card memory Characteristics.

Persistent memory has a major drawback, linked to its electronic properties. Its writing delay is up to 10000 times slower than RAM one. Furthermore, writing in persistent memory may damage the memory cells (the stress problem occurs when using the erase operation: making a bit going from 0 to 1).

EEPROM provides 4 primitive operations:

  • read: reading a value,
  • erase: changing some bits from 0 to 1,
  • write: changing some bits from 1 to 0,
  • update: an erase followed by a write.

Erase is a stressing operation, it can provoke a lapse of the memory cell. It is also 38% slower than a write. Table 3 illustrates this characteristic. This characteristic is also true for FLASHRAM.

Operation
 time for writing a 64 bytes page
erase
 2.77 ms
write
 2 ms

Table 3: Differences between the two writing operations in a typical EEPROM usage.

 

Physical links :

Smart card industries have provided ISO normalization, defining I/O protocols. The wired normalization is called ISO 7816 and is declined in "T=x" protocols. The wireless normalization (for contact less smart card) is defined in ISO SC17 14443. Nevertheless some Smart Card prototypes have used more conventional protocols and physical links. The Table 4 summarizes some of them.

  Type Protocol bandwith Technologies
wired Serial-Line ISO 7816 :
"T=0" & "T=1"		 9600 bauds to
192000 bauds		 Half-Duplex
wired Serial-Line ISO 7816 :
"T=2" & "T=3"		 not yet defined Full-Duplex
wired
USB I - v1.1
 12 Mb/s interleaved
wired
MMC
 20Mb/s interleaved
wired
USB II - v2.0
 480 Mb/s interleaved
wireless
card ISO SC17 14443
 - one to one
wireless
RFID ISO SC31 18000
 - one to many
wireless Bluetooth <1Mb/s Half-Duplex

Table 4: Published SmartCard IOs.

TODO : some words about ISO7816 usage.

Web URLs :

Main smart card manufacturers :

Microcontroler manufacturer :

Usual smartcard chip datasheet :

 

 

II. Smart card operating systems

Smart card softwares until now

Basically there are four parties involved during a smart card life cycle :

  1. Smart card microcontrolers are burned in conventional semiconductor factories ;
  2. Smart cards are shaped in smart card factories (this place is supposed to be the more secured) ;
  3. Smart cards are distributed to smart card issuers ;
  4. Smart card are used to the final users.

The burning phase consist in production of silicon including ROM state.
The shaping phase include plastics production, printing and software initialization.
The distributing phase consist in selling the smart card and embedded software services to the final users.
The usage phase consist in embedded software solicitation each time the user present the smart card to a "smart card reader".

Smart card softwares generations can be classified with regard to this embedding dates. The table 5 shows the proposed classification.

The first generation the software was exclusively embedded on the ship by the microchip manufacturer, as a ROM state. The Smart card manufacturer initialize the software with confidential datas (its called smart card personalization).

The second generation appears to reduce the time-to-market. The main part of the smart card software was burned in ROM, but some part of the application softwares (called "filters") can be loaded in EEPROM by the Smart card manufacturers. Datas are structured in a file-system or a databased representation and so there can be created and managed by everyone in the smart card life-cycle.

The third generation allows applications downloading as well as datas of the second generation. Clearly it a way to improve software reactivity (according to markets evolutions). Ensuring smart cards safety while loading untrusted code is extraordinary more complex than ensuring smart cards safety while loading datas.

Generation

Actors
1st gen.
2nd gen.
3rd gen.
Smart card
user		   Datas Datas & Applications
Smart card
issuer		  
Smart card manufacturers Datas Datas & Applications
semiconductor manufacturers Applications
& OS		 OS OS

Table 5 : Smart card software generations depending to their deployment actor.

Today, each one of this software generations are sold by smart card manufacturers. Public phone and banking smart card are products of the first generation. Generic ISO7816-4 and ISO7816-7 smart cards, Health cards, are examples of the second generation. Generic multos and javacard as used in JavaSim modules for the GSM are examples of the third generation.

Current OS status

The third generation allows applications downloading as well as datas of the second generation. Clearly it a way to improve software reactivity (according to markets evolutions). Ensuring smart cards safety while loading untrusted code is extraordinary more complex than ensuring smart cards safety while loading datas.

 

 

Softwares examples

Smart card softwares of the first generation :

The first example is a typical PIC smart card OS-Application.
This kind of software are implemented with one thousand of assembly code. The assembly code contains 3 basics "components" (i.e. piece of source) not clearly dissociated by the software enginer :

1. Hardware routines

1.1 hardware initialization ;
1.2 serial line IO : encoding / decoding bytes on the serial line ;
1.3 EEPROM writing : management of EEPROM burning system ;
1.4 Cryptographic management.

2. Communication protocol management

2.1 sending the ATR (Answer To Reset) ;
2.2 encoding received command ;
2.3 encoding sent answer.

3. Services automate :

3.1 "certificate" operation ;
3.2 "pin code" operation ;
3.3 "history" operation.

NB: In this context, smart card software expertise consist in the ability to implement safe, tamper-resistant, and low-cost software (in a co-design process with the hardware). The shown example do not present any of this kind of expertises in it implementation (and the public PIC smart card sold does not contain appropriate hardware). It clearly a non public expertise that's make the core-business of the smart card manufacturers.

 

 

Smart card software of the second generation :

This second software example is extracted from the SOSE OpenSource project. If you are interested by this project, take a look to www.opensc.org.

1. Hardware routines (equivalent to the first generation)

1.1 hardware initialization ;
1.2 serial line IO : encoding / decoding bytes on the serial line ;
1.3 EEPROM writing : management of EEPROM burning system ;

2. Communication protocol management (integrated APDU)

2.1 sending the ATR (Answer To Reset) ;
2.2 APDU dispatcher.

3. Operating system services :

3.1 "authentification" command ;
3.2 "ratification" command ;
3.3 "file system" commands ;
3.4 "dedicated" filters.

Smart card software of the third generation :

Smartcard enabling post issuance capabilities (i.e. applications code can by uploaded while the smartcard is used by the end-user). examples of

comment our Camille OpenSource OS
(here)

- To be continue -

Web URLs :

Open source development for smart card :

  • SOSSE: Simple Operating System for Smartcard Education (open source operating system) ;
  • PCSC Lite Source (Smartcard access in Linux Environment) ;

SmartCard Interface APIs :

Smartcard standards :

"Third gen" Smartcards OS :

  • JavaCard is an open source and portable secure operating system to
    ease the development of killer applications for the contactless
    smartcard hype ;
  • ORIGIN-J: a virtual machine that executes true JavaTM bytecode, that
    has been specifically designed for systems with restricted memory
    resources, such as smart cards ;
  • MultOS ;
  • .NET Card ;
  • BasicCard ;
  • A list of Java Virtual Machine targetting embedded devices ;
  • ...