Nfc-emulate-forum-tag2 / Problems with some phones

[jbatea]

Hi everyone,

I try to emulate a type2 tag, with one of the example's functions of libnfc : nfc-emulate-forum-tag2.

That's work everytime with most of phones, but sometimes i have reading problems with a Samsung galaxy s6.

My setup: -Orange pi pc. -Adafruit Pn532. -Samsung s6. -./my_emulate_tag (copy of nfc-emulate-forum-tag2 program, i just add debug)

Expected behaviour: What happening with most of phones and sometimes (~1/10) with a samsung s6:

root@orangepipc:~/my_emulate# ./my_emulate_tag 
NFC device: pn532_uart:/dev/ttyS3 opened
Emulating NDEF tag now, please touch it with a second NFC device
My_emulate_target
My_target_init

In:   
30  00  
Out:  
00  00  00  00  00  00  00  00  00  00  ff  ff  e1  10  06  0f  
In:   
30  04  
Out:  
03  21  d1  02  1c  53  70  91  01  09  54  02  65  6e  4c  69  
In:   
30  08  
Out:  
62  6e  66  63  51  01  0b  55  03  6c  69  62  6e  66  63  2e  
In:   
30  0c  
Out:  
6f  72  67  00  00  00  00  00  00  00  00  00  00  00  00  00  
In:   
50  00  
HALT sent

Unexpected behaviour: What happening with a samsung s6 in most of cases (~9/10) :

root@orangepipc:~/my_emulate# ./my_emulate_tag 
NFC device: pn532_uart:/dev/ttyS3 opened
Emulating NDEF tag now, please touch it with a second NFC device
My_emulate_target
My_target_init

This problems seems to came from RATS command, because nothing happen after the call of "my_target_init", and as said in function documentation:

Warning: Be aware that this function will wait (hang) until a command is received that is not part of the anti-collision. The RATS command for example would wake up the emulator. After this is received, the send and receive functions can be used.

Does someone knows this problem, and maybe a way to solve it?

Thanks.

[jbatea]

Hi everyone, i don't solve my problem, but i have new infos.

I supposed this problem came from the uid of the tag i tried to emulate, let me explain :

Tag i emulate is a 7 bytes uid, but what happened is the reader (with all phones) only see a 4 bytes uid (check with Nxp Tag Reader and Nfc Pro Tools). I emulate the tag with an Adafruit pn532, what i understand is it's impossible to emulate an 7 bytes uid with this board :

http://nfc-tools.org/index.php?title=PN53x http://manpages.org/nfc-emulate-forum-tag2 (The emulated target has only a 4-byte UID while most devices assume a Tag Type 2 has always a 7-byte UID (as a real Mifare Ultralight tag))

So, first question it's is really impossible to emulate a 7 bytes uid with libnfc and Adafruit pn532?

Then, if yes, do a samsung s6 (Samsung S3FWRN5P Nfc Controller) can correctly handle a 4 bytes uid tag?

And if it can't, there is another existing board that can emulate 7 bytes uid tag?

Thanks.

[doegox]

PN532 can't emulate 7-byte UID.

nfc-emulate-uid.c could probably be modified to emulate 7-byte anticollision but this type of emulation is very fragile anyways (hard to setup and non-standard timings) so you're risking even more problems.

And if it can't, there is another existing board that can emulate 7 bytes uid tag?

ChameleonMini can, Proxmark too probably.

[jbatea]

Ok, thanks for your response, i will try something with nfc-emulate-uid, and if i fail to do it, i will take a look on others boards.