| 释义 |
- APDU message command-response pair
- References
- External links
In the context of smart cards, an application protocol data unit (APDU) is the communication unit between a smart card reader and a smart card. The structure of the APDU is defined by ISO/IEC 7816-4 Organization, security and commands for interchange.[1] APDU message command-response pairThere are two categories of APDUs: command APDUs and response APDUs. A command APDU is sent by the reader to the card – it contains a mandatory 4-byte header (CLA, INS, P1, P2) and from 0 to 65 535 bytes of data. A response APDU is sent by the card to the reader – it contains from 0 to 65 536 bytes of data, and 2 mandatory status bytes (SW1, SW2). | Command APDU | | Field name | Length (bytes) | Description |
|---|
| CLA | 1 | Instruction class - indicates the type of command, e.g. interindustry or proprietary | | INS | 1 | Instruction code - indicates the specific command, e.g. "write data" | | P1-P2 | 2 | Instruction parameters for the command, e.g. offset into file at which to write the data | | Lc | 0, 1 or 3 | Encodes the number (Nc) of bytes of command data to follow 0 bytes denotes Nc=0
1 byte with a value from 1 to 255 denotes Nc with the same value
3 bytes, the first of which must be 0, denotes Nc in the range 1 to 65 535 (all three bytes may not be zero) | | Command data | Nc | Nc bytes of data | | Le | 0, 1, 2 or 3 | Encodes the maximum number (Ne) of response bytes expected 0 bytes denotes Ne=0
1 byte in the range 1 to 255 denotes that value of Ne, or 0 denotes Ne=256
2 bytes (if extended Lc was present in the command) in the range 1 to 65 535 denotes Ne of that value, or two zero bytes denotes 65 536
3 bytes (if Lc was not present in the command), the first of which must be 0, denote Ne in the same way as two-byte Le | | Response APDU |
|---|
| Response data | Nr (at most Ne) | Response data | SW1-SW2
(Response trailer) | 2 | Command processing status, e.g. 90 00 (hexadecimal) indicates success |
References1. ^{{cite web|url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=36134 |title=ISO/IEC 7816-4:2005 Identification cards — Integrated circuit cards — Part 4: Organization, security and commands for interchange |publisher=Iso.org |date=2008-10-03 |accessdate=2012-01-27}}
External links- [https://web.archive.org/web/20090624235219/http://cheef.ru/docs/iso/ Smartcard ISOs, contents ]
- [https://web.archive.org/web/20090630004017/http://cheef.ru/docs/HowTo/APDU.info Selected list of smartcard APDU commands]
- [https://web.archive.org/web/20090623030155/http://cheef.ru/docs/HowTo/SW1SW2.info Selected list of SW1 SW2 Status bytes]
- [https://web.archive.org/web/20090330082954/http://www.wrankl.de/SCTables/SCTables.html More information about APDU commands and APDU responses]
3 : Smart cards|ISO standards|IEC standards |