Standards & Protocols

ISO 7816 Parts Guide

Detailed walkthrough of all 15 parts of ISO 7816 covering physical, electrical, T=0/T=1 transport, APDU commands, and security.

| 4 min read
  1. ISO 7816 Parts Guide
  2. Overview of All 15 Parts
  3. Part 3: The Electrical Foundation
  4. Part 4: APDU Structure
  5. Part 5: Application Identifiers
  6. Part 15: PKCS#15 Structure

ISO 7816 Parts Guide

ISO/IEC 7816 is the foundational international standard for contact smart cards. It defines everything from the physical dimensions of the card to the cryptographic authentication protocol. The standard is published in 15 separate parts, each addressing a specific layer of the stack.

Overview of All 15 Parts

Part Title Key Content
7816-1 Physical characteristics ID-1 dimensions, bend/torsion/UV tests
7816-2 Dimensions and location of contacts C1–C8 pad geometry, tolerances
7816-3 Cards with contacts — electrical interface and transmission protocols ATR, T=0, T=1, PPS
7816-4 Organisation, security and commands File system, APDU structure, SELECT, READ, VERIFY
7816-5 Registration of application providers RID + PIX = AID namespace
7816-6 Interindustry data elements BER-TLV tag registry
7816-7 Interindustry commands for Structured Card Query Language SCQL queries on card databases
7816-8 Commands and mechanisms for security operations INTERNAL AUTHENTICATE, EXTERNAL AUTHENTICATE, GET CHALLENGE
7816-9 Commands for card management CREATE FILE, DELETE FILE, TERMINATE CARD
7816-10 Electronic signals and answer to reset for synchronous cards Memory cards (I²C, SPI, synchronous protocols)
7816-11 Personal verification through biometric methods Match-on-cardMatch-on-cardBiometricBiometric matching performed inside the smart card chip.Click to view →, template storage
7816-12 Cards with contacts — USB electrical interface and operating procedures USB 2.0 full-speed on C4/C8 pins
7816-13 Commands for application management in a multi-application environment Superseded by GlobalPlatformGlobalPlatformSoftwareCard application management standard.Click to view → in practice
7816-14 Conformance test plan Test cases for 7816-3 and 7816-4
7816-15 Cryptographic information application PKCS#15 file structure, EF.CIAInfo

Part 3: The Electrical Foundation

7816-3 is the most referenced part. It specifies the low-level communication:

  • Cold reset sequence: VCC → CLK → RST — the card must respond with an ATR within 40,000 clock cycles.
  • T=0T=0ProtocolCharacter-oriented smart card protocol.Click to view →: Byte-oriented half-duplex. The card drives I/O for response bytes; the host drives I/O for command bytes. Error detection via parity.
  • T=1T=1ProtocolBlock-oriented smart card protocol.Click to view →: Block-oriented. Supports chaining (multi-block commands/responses), a CRC or LRC epilogue field, and independent retry on block errors. Required for larger APDUs.
  • PPS: Protocol and Parameter Selection — allows host and card to negotiate higher baud rates and switch between T=0 and T=1.

Part 4: APDU Structure

Every command to a smart card follows the 7816-4 APDUAPDUProtocolCommunication unit between card and reader.Click to view → structure:

Command APDU:
  CLA  INS  P1  P2  [Lc  Data...]  [Le]
  1B   1B   1B  1B   1B   nB        1B

Response APDU:
  [Data...]  SW1  SW2
    nB        1B   1B
Field Meaning
CLA Class byte — channel number, secure messagingsecure messagingProtocolCryptographic protection of APDU command/response pairs.Click to view → indicator
INS Instruction — e.g., 0xA4 SELECT, 0xB0 READ BINARY
P1/P2 Parameters — context-specific
Lc Length of command data
Le Expected length of response data
SW1 SW2 Status word — 90 00 = success

Use the APDU Builder to construct and decode APDU strings interactively.

Part 5: Application Identifiers

The AID (Application Identifier) namespace is managed under 7816-5:

  • RID (5 bytes): Registered Application Provider Identifier — assigned by the ISO/IEC Registration Authority.
  • PIX (0–11 bytes): Proprietary application Extension — defined by the AIDAIDProtocolUnique identifier for card applications.Click to view → owner to distinguish applications.

Well-known RIDs include A0 00 00 00 03 (Visa), A0 00 00 00 04 (Mastercard), A0 00 00 03 97 (Interac).

Part 15: PKCS#15 Structure

7816-15 defines how cryptographic objects (keys, certificates, authentication data) are laid out in the file system — a standard that the PKI on Smart Cards guide builds on directly. Key files include:

File Contents
EF.DIR AID directory — lists PKCS#15 application
EF.CIAInfo Card Information Application metadata
EF.ODF Object Directory File — points to key/cert/data object DFs
EF.PrKDF Private Key Directory File
EF.CDF Certificate Directory File
EF.AODF Authentication Object Directory File (PINs)

Understanding which ISO 7816ISO 7816StandardPrimary standard for contact smart cards.Click to view → part governs a behaviour is essential when reading vendor documentation or writing protocol-level code with the PC/SC Programming Guide.

अक्सर पूछे जाने वाले प्रश्न

Our guides cover a range of experience levels. Getting Started guides introduce smart card fundamentals. Security guides address Common Criteria certification and key management. Programming guides target developers working with APDU commands, JavaCard applets, and GlobalPlatform card management.