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Smart card
Plastic card with embedded processor - this page is a stub

A smart card (SC) 1 is (plastic) card with one or more integrated circuits (ICs), used to control access to a resource [1]. It is typically a PVC plastic credit-card-sized card with an embedded microprocessor, volatile memory (RAM), non-volatile memory (EEPROM) and program storage space (ROM), commonly implemented as a monolithic (single-chip) solution. Many smart cards are interfaced via metal contact pads, whilst others are contactless. Some cards support both.

Smart cards typically provide personal identifi­ca­tion, authentication, data storage, encryption and application processing. Applications include identification, access control, computer security, financial, transport, healthcare, schools, etc.

The are three basic card sizes (ID-1 to ID-3) of which ID-1 is arguably the most popular one as it is used for credit cards and bank cards. The universal integrated circuit card (UICC) [2] – used as a Subscriber Identity Module (SIM card) in mobile phones [3] – is also a type of smart card. Initially, SIM cards were supplied at ID-1 size.

The smart card was invented in 1967 by the German engineer Helmut Gröttrup [4]. His patents DE1574074 and DE1574075 describe a device with an integrated circuit (IC) and contact-less (inductive) communication. The IC, on which the smart card is based, was invented in 1959 by Robert Noyce at Fairchild Semiconductor (USA). The most common type of smart card that is used for bank and telephone cards, was invented in 1974 by French developer Roland Moreno [8]. 2

In 2015, 10.5 billion smart card ICs were manu­factured anually, about half of which was used for SIM cards in 2G, 3G, 4G and 5G telephones [1].

  1. Also known as a Chip Card (CC), Integrated Circuit Card (ICC) or IC card.
  2. Application developers had to pay royalties to Moreno's company Innovatron SA.

Devices that use smart cards
Access card for secure telecommunication devices, used as a Crypto Ignition Key (CIK)
PNVX secure crypto telephone, fax and data products
PFDX fact encryptor
PPSX X.25 data encryptor
2Mb link encryptor
Computer and network security PCMCIA card for the Dutch Government
Thales TCE-621/B link encryptor
Thales TCE-621/M Mobile IP encryptor
HC-3300 Secure Crypto Phone
HC-4220 Fax Encryptor
HC-2203 PSTN Phone Encryptor
Elcrovox 1/4D narrow band voice and data terminal (STU-II compatible)
Siemens Crypset 100 PSTN crypto phone
The Siemens DSM Voice telephone encryptor
Elcrodat 6/2 ISDN voice and data encryptor
SINA bulk encryptor for IP-based networks
Hardware Security Modules
NEVO FX credit card recorder
Nagra CCR covert recorder at the size of a credit card (no image available)
Nagra Credit Card Transmitter (CCT)
Smart card readers
Internal smart card reader with ISA-bus expansion card
External smart card reader with RS232 interface
External smart card reader with RS232 interface

Information on smart cards can be accessed in one or more of the following ways:

  • Contact pads
    Most smart cards have a physical (electrical) interface in the form of 6 or 8 contact pads at the top surface. It allows the host (i.e. the card reader) to communicate directly with the card's internal microcontroller. The card is powered via the contact pads as well.

  • Contactless
    Newer cards may offer a wireless interface. Such cards are equipped with Near Field Com­mu­nication (NFC) technology. It is sufficient to hold the card close to the reader. The card is wirelessly powered by an electromagnetic field transmitted by the host (i.e. the reader). NFC is also available in some mobile phones, which can then be used as a smart card. Today, most banks cards, ID cards and passports have an embedded NFC chip.

  • Magnetic stripe
    The backside of a smart card – typically the older ones – may contain a magnetic strip on which data can be stored. This was typically used on older bank cards for authentication, often in combination with a PIN. Magnetic strips are vulnerable to spoofing.

  • Embossing
    In the early days of credit cards, the name and account number of the card holder were often embossed rather than printed. This allowed a direct copy to be made on a sales slip, by means of a swipe device and carbon paper. Embossing is always at the front side.
Four ways of accessing information on a smart card

The 'smart' part of a smart card comprises the following hardware, which in most cases is combined in a single monotlithic chip:

  • Microcontroller
    e.g. 68HC05 (8-bit)
  • Voltatile memory
  • Program memory
  • Storage
  • Interface
    Contact pads, contactless
Card sizes
There are three basic sizes for smart cards (ID-1, ID-2 and ID-3), plus an additional smaller one for mobile telephony (ID-000), defined in ISO/IEC 7810 [5]. The largest card size (ID-3) is typically used for passport ID cards, whilst the smaller ID-1 is used for bank cards, identification cards and access control. The diagram below shows the dimensions of ID-1 to ID-3. The thick­ness of all cards is 0.68 to 0.84 mm. The smaller ID-000 is part of the SIM card specification.

The four basic card sizes defined in ISO/IEC 7810

ISO Dimensions Description Alternative
ID-1 85.6 × 53.98 mm ID card, bank card, SIM CR-80
ID-2 105 × 74 mm Old style ID, visa  
ID-3 125 × 88 mm Passport  
ID-000 25 15 mm Mini SIM 2FF
Contact layout
A smart card with a physical contact interface may have 8 contact pads, as defined in ISO/IEC 7816-2. The contacts are numbered C1 to C8, starting with C1 at the top left, as shown in the table and in the diagram below. Contacts C4 and C8 are optional and may be omitted. They are for vendor-specific applications. Note that there are many variants of the contact pad layout.

Pin Name Description   Pin Name Description
C1 Vcc Supply voltage   C5 GND Ground (0V)
C2 RST Reset signal   C6 Vpp Variable supply voltage
(e.g. programming voltage)
C3 CLK Clock signal   C7 I/O Data input/output
C4 opt. Reserved for future use
or parts of ISO/IEC 7816
Sometimes used for USB
  C8 opt. Reserved for future use
or parts of ISO/IEC 7816
Sometimes used for USB
Official assignment of the contact pads

Contact positions
The position of the 6 or 8 contact pads are always referenced from the top left corner of the ID-1 size card. In the initial ISO 7816-2 specification of 1988, the contact pads were located in the top left corner of the ID-1 card, as shown in the diagram below. This format is now depricated.

Position of the contact pads prior to 1990. This format is now DEPRICATED.

In 1990, the ISO/IEC 7816-2 standard was revised and the entire contact area (with the chip fitted below it) was moved down to its current position. From 1990 onwards, the position of the contact pads is as shown in the diagram below. Note that the lower two contacts (C4 and C8) are vendor-specific and may be omitted. C4 and C8 are missing from most bank cards and SIM cards.

Position of the contact pads from 1990 onwards according to ISO/IEC 7816-2.

The diagram below shows the minimum pad dimensions and positions according to the ISO/IEC 7816-2 standard. This is where the contact pads mate with the contact springs in the receptacle. Manufacturers can use any shape and layout, as long as these minimum requirements are met.

Minimum contact pad dimensions and positions according to ISO/IEC 7816-2.

Supply voltages
Most smart cards must be powered externally, generally via the gold-plated contact pads at the front. Depending on the age of the card, a higher or lower Vcc voltage must be applied. There is no way to determine the correct voltage, so its up to the terminal to try the lowest voltage first, and then progressively raise the voltage until the card responds. The following power classes are currently defined:

  1. 5V
  2. 3.3V
  3. 1.8V
SIM cards
In mobile telephony, a Subscriber Identity Module or SIM card is used to uniquely identify the subscriber and hence the corresponding telephone number. Initially, all SIM cards had the ID-1 format — in SIM terminalogy known as 1FF — but with the introduction of smart phones, the large dimensions of the ID-1/1FF were no longer realistic. Progressively smaller cards were deve­loped for later telephones, resulting in the 2FF, 3FF and 4FF formats shown below. In most cases, the SIM card is still supplied at 1FF size (ID-1), but is pre-cut in such a way that smaller cards can be extracted by the customer, simply by breaking it out. The smallest user-installable SIM is 4FF.

The current trend (2024) is towards the use of the Embedded SIM, or eSIM, which no longer requires the user to physically install it. An eSIM is already built into the mobile phone by the manufacturer, and can be programmed externally. The eSIM form factor is known as the MFF2 format. Some telephones have a built-in eSIM as well as a slot for a regular removable 4FF card.

Answer To Reset   ATR
When a smart card is powered on, or when reset is asserted, it produces a so-called Answer-To-Reset (ATR) — a string of hexadecimal values (bytes) that allows the card reader to check for compatibility. The ATR has a variable length that should be parsed by the reader on-the-fly [9].

The Philips TB-100 card, for example, produces the following ATR:
3F 67 25 04 21 20 00 07 68 90 00

 List of known ATRs (off-site)

  1. DE1574074 - Nachahmungssicherer Identifizierungsschalter
    Dipl.-Ing. Helmut Gröttrup. 6 February 1967.

  2. DE1574075 - Identifizierungsschalter mit induktiever Zuordnung
    Dipl.-Ing. Helmut Gröttrup. 6 February 1967.

  3. AT287366 - Identifizierungsschalter
    Dipl.-Ing. Helmut Gröttrup. 13 September 1968.

  4. US3,641,316 - Identification System
    Jurgen Dethloff, Helmut Grottrup (Germany), 17 August 1970.

  5. US3,678,250 - Identification Switch
    Jurgen Dethloff, Helmut Grottrup (Germany), 15 September 1969.
Media coverage
  1. Roland Moreno's ubiquitous invention
    Google Arts & Culture, The Roland Moreno Foundation.
  1. George Selimis et al., Software and Hardware Issues in Smart Card Technology
    IEEE Communications Surveys $ Tutorials, Vol. 11, No. 3, Q3 2009.

  2. De Smart Card Algemeen (Dutch)
    E.R. Lekanne-Deprez, C. Bolt. Hogeschool Utrecht (Hilversum).
    Undated. pp. 29-31.

  3. Encryptie (Dutch)
    Nederlands Genootschap voor Informatica, Afdeling Beveiliging.
    Kluwer Bedrijfswetenschappen, 1993. pp. 68-77.
    ISBN 90-267-1862-4.
  1. Wikipedia, Smart card
    Visited 21 March 2024.

  2. Wikipedia, Universal integrated circuit card
    Visited 21 March 2024.

  3. Wikipedia, SIM card
    Visited 21 March 2024.

  4. Wikipedia, Helmut Gröttrup
    Visited 22 March 2024.

  5. Wikipedia, ISO/IEC 7810
    Visited 21 March 2024.

  6. Wikipedia, ISO/IEC 7811
    Visited 21 March 2024.

  7. Wikipedia, ISO/IEC 7816
    Visited 21 March 2024.

  8. Wikipedia, Roland Moreno
    Retrieved 26 March 2024.

  9. Wikipedia, Answer to reset
    Retrieved 26 March 2024.

  10. EFTlab, List of known ATRs
    Retrieved 26 March 2024.
Further information
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© Crypto Museum. Created: Saturday 23 March 2024. Last changed: Wednesday, 27 March 2024 - 14:38 CET.
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