CCID descriptor statistics: bNumEndpoints

Article from the serie "CCID descriptor statistics"

The bNumEndpoints field is a number value from the CCID USB descriptor: Number of endpoints used by this interface (excluding endpoint zero).

bNumEndpoints	#	%
3	228	89.76 %
2	16	6.30 %
0	6	2.36 %
1	4	1.57 %

According to the CCID specification: For Integrated Circuit(s) Cards Interface Devices (CCID)

• 02h uses bulk-IN and bulk-OUT
• 03h uses bulk-IN, bulk-OUT and interrupt –IN

So the possible values are 2 or 3 for a CCID device.

According to the ICCD specification:

• 00h does not use further endpoint
• 01h uses interrupt-IN
• 02h uses bulk-IN and bulk-OUT
• 03h uses bulk-IN, bulk-OUT and interrupt –IN

NOTE 01h indicates that the control endpoints are used for data transmission and interrupt-IN for notification of card specific events sent from the USB-ICC to the host.

Devices with bNumEndpoints = 0

• Aktiv Co., ProgramPark Rutoken Magistra
• BIFIT iBank2Key
• Gemalto PDT
• OCS ID-One Cosmo Card USB Smart Chip Device
• Philips Semiconductors JCOP41V221
• SchlumbergerSema SchlumbergerSema Cyberflex Access

Devices with bNumEndpoints = 1

• Giesecke & Devrient GmbH Star Sign Card Token 350 (ICCD)
• Giesecke & Devrient GmbH Star Sign Card Token 550 (ICCD)
• KEBTechnology KONA USB SmartCard
• Philips Semiconductors SmartMX Sample

To know if a device is a CCID or ICCD device use the bInterfaceProtocol field. We find again the 10 ICCD devices as found in bInterfaceProtocol. But we note that there is no matching between bNumEndpoints = 0 or 1 and Version A or B of ICCD protocol.