CCID descriptor statistics: dwMaxIFSD

Article from the serie "CCID descriptor statistics"

The dwMaxIFSD field is a number value from the USB CCID descriptor: Indicates the maximum IFSD supported by CCID for protocol T=1.

dwMaxIFSD # %
254 176 69.29 %
252 34 13.39 %
247 16 6.30 %
0 12 4.72 %
1024 4 1.57 %
256 3 1.18 %
1400 2 0.79 %
1041 1 0.39 %
123 1 0.39 %
2048 1 0.39 %
240 1 0.39 %
248 1 0.39 %
49 1 0.39 %
64 1 0.39 %


Some values may look strange or bogus:
  • 0 is used by 5% of readers. It is not a bug for a ICCD device with a T=0 card inside because dwMaxIFSD is only used with a T=1 card.
    Readers with dwMaxIFSD = 0 are:
    • ATMEL AT91SC192192CT-USB ICCD reader
    • ATMEL AT98SC032CT-USB
    • ATMEL VaultIC420 Smart Object
    • ATMEL VaultIC440
    • ATMEL VaultIC460
    • Gemalto Hybrid Smartcard Reader
    • IID AT90S064 CCID READER
    • INSIDE Secure VaultIC 405 Smart Object
    • INSIDE Secure VaultIC 441 Smart Object
    • Inside Secure VaultIC 420 Smart Object
    • Inside Secure VaultIC 440 Smart Object
    • Inside Secure VaultIC 460 Smart Object
    • MYSMART MySMART PAD V2.0
    • SchlumbergerSema SchlumbergerSema Cyberflex Access
    • SecuTech SecuTech Token
    • TianYu CCID Key TianYu CCID SmartKey
    Among them only the MYSMART MySMART PAD V2.0 is bogus with dwMaxIFSD = 0 and dwProtocols = 0x0000 0x0300 (should be 0x0000 0x0003 for T=0 and T=1).
  • The maximum value for dwMaxIFSD is dwMaxCCIDMessageLength - 10.
    Readers with  dwMaxIFSD > dwMaxCCIDMessageLength - 10, so bogus readers, are:
    • Aktiv Co., ProgramPark Rutoken Magistra
    • CCB eSafeLD
    • Feitian bR301
    • Free Software Initiative of Japan Gnuk
    • Gemalto PDT
    • Giesecke & Devrient GmbH Star Sign Card Token 550 (ICCD)
    • OCS ID-One Cosmo Card USB Smart Chip Device
    • Philips Semiconductors JCOP41V221
    • Philips Semiconductors SmartMX Sample
    • Planeta RC700-NFC CCID
    • Yubico Yubikey NEO CCID
    • Yubico Yubikey NEO OTP+CCID