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nfc-emulate-uid(1)		libnfc's examples	      nfc-emulate-uid(1)

NAME
     nfc-emulate-uid - NFC target emulation command line tool based on libnfc

SYNOPSIS
     nfc-emulate-uid [OPTIONS] [UID]

DESCRIPTION
     nfc-emulate-uid  is  a tag emulation tool that allows one to choose any tag
     UID. Tag emulation is one of the main added features in NFC. But  to  avoid
     abuse  of	existing systems, manufacturers of the NFC controller intention-
     ally did not support emulation of fully customized UID but only of "random"
     UIDs, which always start with 0x08.  The nfc-emulate-uid tool  demonstrates
     that  this  can still be done using transmission of raw frames, and the de-
     sired UID can be optionally specified.

     This makes it a serious threat for security systems that rely only  on  the
     uniqueness of the UID.

     Unfortunately, this example can't directly start in fully customisable tar-
     get  mode.  Just  after launching this example, you will have to go through
     the hardcoded  initial  anti-collision  with  the	0x08-prefixed  UID.   To
     achieve it, you can e.g. send a RATS (Request for Answer To Select) command
     by  using a second NFC device (placed in target's field) and launching nfc-
     list or nfc-anticol. After this first step, you now have a NFC device (con-
     figured as target) that really emulates a custom UID.  You  could	view  it
     using the second NFC device with nfc-list.

     Timing control is very important for a successful anti-collision sequence:

     -	The  emulator  must be very fast to react: Using the ACR122 device gives
     many timing issues, "PN53x only" USB devices also give some  timing  issues
     but  an  embedded	microprocessor would probably improve greatly the situa-
     tion.

     - The reader should not be too strict  on	timing	(the  standard	is  very
     strict).  The OmniKey CardMan 5321 is known to be very large on timings and
     is a good choice if you want to experiment with this emulator with a toler-
     ant reader.  Nokia NFC 6212 and Pegoda readers  are  much	too  strict  and
     won't be fooled.

OPTIONS
     UID 8 hex digits format that represents desired UID (default is DEADBEEF).

IMPORTANT
     ACR122  devices  (like  touchatag,  etc.) can be used by this example (with
     timing issues), but if something goes wrong, you will have to unplug/replug
     your device. This is not a libnfc's bug, this problem is  due  to	ACR122's
     internal MCU in front of NFC chip (PN532).

BUGS
     Please report any bugs on the libnfc issue tracker at:
     https://github.com/nfc-tools/libnfc/issues

LICENCE
     libnfc is licensed under the GNU Lesser General Public License (LGPL), ver-
     sion 3.
     libnfc-utils  and	libnfc-examples  are covered by the the BSD 2-Clause li-
     cense.

AUTHORS
     Roel Verdult <roel@libnfc.org>

     This manual page was written by Romuald Conty <romuald@libnfc.org>.  It  is
     licensed under the terms of the GNU GPL (version 2 or later).

libnfc				  June 26, 2009 	      nfc-emulate-uid(1)

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