Proxmark3 community

joswr1ght

Member

Registered: 2013-10-17

Posts: 3

Help Reading Phidgets Tag

I have a Phidgets keyboard wedge reader that can read and decode tags.  I'd like to read and decode the tag using the Proxmark as well, and am looking for some guidance.

Running firmware from SVN:

proxmark3> hw ver
#db# Prox/RFID mark3 RFID instrument                 
#db# bootrom: svn 671 2013-03-07 17:12:17                 
#db# os: svn 852 2014-05-25 00:34:12                 
#db# FPGA image built on 2012/ 1/ 6 at 15:27:56                 
uC: AT91SAM7S256 Rev A          
Embedded Processor: ARM7TDMI          
Nonvolatile Program Memory Size: 256K bytes          
Second Nonvolatile Program Memory Size: None          
Internal SRAM Size: 256K bytes          
Architecture Identifier: AT91SAM7Sxx Series          
Nonvolatile Program Memory Type: Embedded Flash Memory          

"hw tune" before and after tag look good:

proxmark3> hw tune
#db# Measuring antenna characteristics, please wait...                 
#db# Measuring complete, sending report back to host                 
          
# LF antenna: 13.83 V @   125.00 kHz          
# LF antenna: 21.89 V @   134.00 kHz          
# LF optimal: 24.84 V @   131.87 kHz          
# HF antenna:  0.81 V @    13.56 MHz          
# Your HF antenna is unusable.          
proxmark3> hw tune
#db# Measuring antenna characteristics, please wait...                 
#db# Measuring complete, sending report back to host                 
          
# LF antenna: 12.76 V @   125.00 kHz          
# LF antenna: 22.69 V @   134.00 kHz          
# LF optimal: 23.63 V @   131.87 kHz          
# HF antenna:  0.90 V @    13.56 MHz          
# Your HF antenna is unusable.          

Reading the tag with the Phidgets keyboard wedge gives me: 0103f42f83.

Here is the plot: https://www.dropbox.com/s/r5s8ivta5xhh8iy/phidget-tag.png

And here is the data samples file: https://www.dropbox.com/s/rct0k1mthzljrbu/phidgets.pm3

From the plot, I'd guess this is an ASK tag, but that produces a broken-looking plot: https://www.dropbox.com/s/8msqp1p2xhzurcx/phidget-tag-askdemod.png

And "data mandemod" doesn't return a bitstream.

Am I way off base here on this tag?  What would be the next analysis step?

Thanks,

-Josh

midnitesnake

Contributor

Registered: 2012-05-11

Posts: 151

Re: Help Reading Phidgets Tag

Could it be a Bi-Phase modulated signal?

marshmellow

Contributor

From: US

Registered: 2013-06-10

Posts: 2,302

Re: Help Reading Phidgets Tag

repeating bitstream:

1111111110000000011000000011011110010010010111110100010011011110

Which is a EM41xx format with the ID of: 0103F42F83
Try this command on the proxmark:
lf em4x em410xread 64

Last edited by marshmellow (2014-05-27 19:01:48)

iceman

Administrator

Registered: 2013-04-25

Posts: 9,507

Website

Re: Help Reading Phidgets Tag

Tag ID:  01 03 F4 2F 83
Unique ID:  08 0C F2 4F 1C