More on GPShell commands

It can be hard to know the AID of the applet instance to select with the GPShell select command, and the accompanying readme really doesn't enlighten the novice developer.

I find that the best way to get the necessary info is to open a secure channel to the Card Manager, and then do a get_status instruction. For example:

select -AID a000000003000000
mode_211
enable_trace
establish_context
card_connect
open_sc -security 1 -keyind 0 -keyver 0 -mac_key 404142434445464748494a4b4c4d4e4f -enc_key 404142434445464748494a4b4c4d4e4f
get_status -element 40

This returns all selectable applet instances on the card.

Note that the select command requires hex values: ASCII characters don't seem to be supported (with or without single or double quotation marks), and an error is not thrown; instead some default domain or package on the card is selected (APDU 00A4040000). This can lead to extreme frustration on the part of the developer when all subsequent test APDU's return the status word 6D00 (unknown INS value).

Card Recognition Data

To get the GPShell open_sc command to work with an applet instance (not the Security Domain), we must ensure that the correct Secure Channel Protocol implementation number is specified.

This number can be retrieved from the Card Recognition Data TLV fields via the OpenPlatform get-data command on tag 0x66 (send APDU 80CA0066) after selecting the Card Manager. For example, with the Nokia 6131 NFC phone, the command returns:

66 4C
--73 4A
----06 07 2A864886FC6B 01
--60 0C
----06 0A 2A864886FC6B 02 02 01 01
--63 09
----06 07 2A864886FC6B 03
--64 0B
----06 09 2A864886FC6B 04 02 55
--65 0B
----06 09 2B8510864864020103
--66 0C
--06 0A 2B060104012A026E0102
9000

The response is formatted into TLV fields according to GP 2.1.1 Section F.2 or GP 2.2 Section H.2, "Structure of Card Recognition Data".

The field at tag 64 (offset 50 in the unformatted string) aka "application tag - GP OID 04" has scp=0x2 (SCP02), i=0x55=85 (scpimpl). Note that this is different from the default i=0x15!

The field at tag 60 aka "application tag - GP OID 02" specifies the GlobalPlatform version, namely GP2v2.1.1 (compare with value in given by ATR and OpenPlatform get-cplc command). This gives a clue as to the Java Card version that can be expected (2.2.1).

The GPShell command to open a secure channel (MAC and ENC) to an applet in the Secure Domain would then be (after selecting the applet):

open_sc -security 3 -keyind FF -keyver 0 -mac_key 404142434445464748494a4b4c4d4e4f -enc_key 404142434445464748494a4b4c4d4e4f -scpimpl 85 -scp 2

where "-scpimpl 85" specifies the decimal value of the SCP number.

Note: according to the GP spec. H.3, the GP select command on the Security Domain may return TLV values which - if present - override the Card Recognition Data described previously. What exactly this implies I still have to figure out ...


****
Update: I discovered that the COS on the IC in the Nokia is G&D SmartCafe Expert 3.1 which is indeed Java Card 2.2.1 compliant. See this post.

Smart Card SCP02

GlobalPlatform Secure Channel Protocol 2 (GP SCP02) allows secure communication with an applet. It is documented as Appendix E in the GP Card Specification 2.1.1

GP card-side classes (org.globalplatform.GPSystem and org.globalplatform.SecureChannel, included in JCOP Tools gp211.jar or in GP Card Specification) make it easy to process, wrap and unwrap secured APDUs.

Card managers supporting SCP02 include JCOP Tools and GPShell.

(No info on terminal-side classes for SCP02 yet. Watch this space.)

SCP03 has been specified by GP middle of 2007 as part of Card Specification 2.2 but it's not clear if there are any implementations which support this yet.

Tips for managing sessions and applets:

• Remember that have only 10 tries to authenticate to a JCOP card manager. Successfully authenticating will reset its internal counter. After 10 failures the card manager will be locked and cannot be unlocked, although the applets on the card will remain usable. This is different than the situation where the card itself is in GP state CARD_LOCKED, which is reversible.
  Using the wrong key-set is the most common mistake people make. Confirm that you are using the right key-set: read the tutorials on-line and contact your vendor if you don't have supporting documentation for the card.
  JCOP Tools get-cplc prints the production info for the card (aka ISD), which you can send to the card vendor (or google!) to get the key-set. If you are already authenticated to the card and want to confirm the default key-set number, use init-update: the response APDU has the key-set number you used to authenticate in the 11th byte, and the SCP version in the 12th byte. (Refer to GP2.1.1 Appendix D4.1 and D4.2 for init-update and ext-auth commands). Remember that using init-update when not authenticated counts as authentication failure, which will use up one of your tries! First reset the ISD failure counter by authenticating successfully, then continue experimenting.
• SCP02 requires key-type CBC (valid key types are DES, DES-ECB, DES-CBC, RSA-PRIV, RSA-PUB, RSA-CRT, DSA-PRIV, or DSA-PUB). If you specified SCP02 ENC+MAC by using JCOP Tools command ext-auth enc, JCOP Tools will automatically set key type to CBC even if you set key type for example DES-ECB.
• The card has several life-cycle states, usually READY or SECURED (the latter requiring external authentication level C-MAC at least). Refer to GP2.1.1 Section 5.1.
  

Nokia NFC SDK

Nokia rolled out their 6131 NFC model around January 2007, aimed mainly at developers. To upload your own MIDlets to the phone you have to ask your dealer to factory unlock the phone, or do it yourself via an Unlock MIDlet (Nokia wiki listed below has a link) which will prevent it from working with trusted MIDlets and applets afterwards. Nokia makes up for this royal pain by offering a decent NFC and MIDlet SDK, and the developer community for their products is quite big and provides good support.

Good places to start reading:

• Official Nokia NFC SDK page
  
• Forum Nokia Documentation and Tools pages
• Forum Nokia wiki FAQ for 6131 NFC
  
• Nokia Secure Chip FAQ
• Nokia MIDlet development tutorial

At the time of this posting the PDF for the Nokia 6131 NFC SDK Programmer's Guide was not available via the official Nokia site, so instead I got it from the Uni. Lüneburg FTP along with the Nokia SDK and other docs. (All the guide PDFs and supporting documentation are included in the SDK.)

Note: Unlocked Nokia 6131 NFC phones all use the same key-set, namely

42/1/DES-ECB/404142434445464748494a4b4c4d4e4f
42/2/DES-ECB/404142434445464748494a4b4c4d4e4f
42/3/DES-ECB/404142434445464748494a4b4c4d4e4f

and security protocol is the GP default: SCP02 option 15 (CMAC+ENC, refer to Nokia 6131 NFC Technical Product Description v1.0 section 7.2, p 26). For JCOP Tools this translates to using ext-auth enc, while in GPShell you would use mode_211 and open_sc -security 3 [...] A detailed discussion with examples can be found on the Nokia Forum. For detailed definitions of SCP02 and its options, refer to Global Platform Card Specification 2.1.1 Appendix E.1.1, p213.