dedb627e82
git-svn-id: https://vsmartcard.svn.sourceforge.net/svnroot/vsmartcard@654 96b47cad-a561-4643-ad3b-153ac7d7599c
93 lines
4.2 KiB
ReStructuredText
93 lines
4.2 KiB
ReStructuredText
.. |vpicc| replace:: :abbr:`vpicc (virtual smart card)`
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.. |vpcd| replace:: :abbr:`vpcd (virtual smart card reader)`
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.. |APDU| replace:: :abbr:`APDU (Application Protocol Data Unit)`
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.. |SWs| replace:: :abbr:`SWs (status bytes SW 1 and SW 2)`
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.. |SAM| replace:: :abbr:`SAM (Secure Access Module)`
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*****************************
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Creating a Virtual Smart Card
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*****************************
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|vpcd| communicates over a socked with |vpicc| usually on port ``0x8C7B``
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(configurably via :file:`/etc/reader.conf.d/vpcd`). So you can connect
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virtually any program to the virtual smart card reader, as long as you respect
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the following protocol:
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============= ==================== ============= =============
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|vpcd| |vpicc|
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---------------------------------- ---------------------------
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Length Command Length Response
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============= ==================== ============= =============
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``0x00 0x01`` ``0x00`` (Power Off) (No Response)
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``0x00 0x01`` ``0x01`` (Power On) (No Response)
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``0x00 0x01`` ``0x02`` (Reset) (No Response)
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``0x00 0x01`` ``0x04`` (Get ATR) ``0xXX 0xXX`` (ATR)
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``0xXX 0xXX`` (APDU) ``0xXX 0xXX`` (R-APDU)
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============= ==================== ============= =============
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The communication is initiated by |vpcd|. First the length of the data (in
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network byte order, i.e. little endian) is sent followed by the data itself.
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=======================================
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Implementing a ISO 7816 like Smart Card
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=======================================
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|vpicc| includes an emulation of a card acting according to ISO 7816. This
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includes all standard commands for file management and secure messaging.
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Let's assume we want to create a cryptoflex card, that acts mostly according to
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ISO 7816. In this example we only want to add little things that differ from
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ISO 7816. But as for most complex software you need to know where you need to
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hook into. Here we only want to give an overview to the design, the complete
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details can be found in section `Documentation to Virtual Smart Card`_
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Back to the cryptoflex example. :class:`VirtualICC` provides the connection to
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the virtual smart card reader. It fetches an |APDU| and other requests from the
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|vpcd|. In :class:`VirtualICC` an |APDU| is only a buffer that is forwarded to
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the smart card OS. First we modify :class:`VirtualICC` to recognize a new type
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``"cryptoflex"`` and to load :class:`CryptoflexOS`. The :class:`CardGenerator`
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is used to create a file system and a |SAM| specific to the cryptoflex (we come
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back to this later).
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.. literalinclude:: virtualsmartcard/VirtualSmartcard.py
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:pyobject: VirtualICC.__init__
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:emphasize-lines: 20,28-29
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Responses from our cryptoflex card look the same as for the 7816 card. But when
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a command was successfull (or not) there is a little difference in what is
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returned. So we need to edit :class:`CryptoflexOS.formatResult`, which is
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called to encode the |SWs| and the resulting data.
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.. literalinclude:: virtualsmartcard/VirtualSmartcard.py
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:pyobject: CryptoflexOS.formatResult
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Note that this also requires some insight knowledge about how
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:class:`Iso7816OS` works (see `below <Documentation to Virtual Smart Card>`_).
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The previously created |SAM| handles keys, encryption, secure messaging and so
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on (we will not go into more details here). The file system creates, selects
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and reads contents of files or directories. File handling for our cryptoflex
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card is similar to ISO 7816, but the meaning of P1, P2 and the |APDU| data is
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completely different when creating a file on the smart card. So we derive
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:class:`CryptoflexMF` from :class:`MF` and modify :class:`CryptoflexMF.create`
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to our needs.
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.. literalinclude:: virtualsmartcard/cards/cryptoflex.py
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:pyobject: CryptoflexMF.create
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As you can see it is quite simple to extend the virtual smart card to your
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requirements. Simply overwrite those functions, that differ from ISO 78166. But
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as said before, the virtual smart card is quite complex and you might have to
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read some documentation or even source code to find out where it's best to do
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your modifications...
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===================================
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Documentation to Virtual Smart Card
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===================================
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.. toctree::
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api/virtualsmartcard
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