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#1 2019-09-02 15:19:13

pizza_4u
Contributor
Registered: 2018-07-28
Posts: 2

EM4x50 or not?

Can someone share some lights about the current implementation of EM 4x50?

I have a (yet) unknown tag. hw tune shows drop at 125 kHz. Original repo shows it as EM4x50. The RFID repo shows it as unknown.


org repo:

proxmark3> lf search u
NOTE: some demods output possible binary
  if it finds something that looks like a tag          
False Positives ARE possible
          

Checking for known tags:
          
Found data at sample: 3591 - using clock: 64          
Block 0: 00000000          
Parities Passed          

Valid EM4x50 ID Found!

proxmark3> lf em 4x50read 

Note: one block = 50 bits (32 data, 12 parity, 6 marker)          

Block 0:          
00000000 0 -> 0x00          
00000000 0 -> 0x00          
00000000 0 -> 0x00          
00000000 0 -> 0x00          
          
00000000 0 -> 0x00          
Parity Passed          
Found data at sample: 3591 - using clock: 64          
Block 0: 00000000          
Parities Passed

RFID repo:

[usb] pm3 --> lf search u
[=] NOTE: some demods output possible binary          
[=] if it finds something that looks like a tag          
[=] False Positives ARE possible          
[=]           
[=] Checking for known tags...
          
[-] No known 125/134 kHz tags found!           
          
[=] Checking for unknown tags:
          
[-] no repeating pattern found, try increasing window size          
[=] Possible auto correlation of 3520 repeating samples          
[=] Possible 440 bytes          
[-] 
[-] No data found!

[usb] pm3 --> lf read
#db# LF Sampling config           
#db#   [q] divisor.............95 ( 125 kHz )          
#db#   [b] bps.................8          
#db#   [d] decimation..........1          
#db#   [a] averaging...........Yes          
#db#   [t] trigger threshold...0          
#db# Done, saved 40000 out of 40000 seen samples at 8 bits/sample          
#db# buffer samples: 80 80 53 1d 00 00 00 00 ...          
Reading 39999 bytes from device memory
          
Data fetched          
Samples @ 8 bits/smpl, decimation 1:1 
[usb] pm3 --> data sample
Reading 39999 bytes from device memory
          
Data fetched          
Samples @ 8 bits/smpl, decimation 1:1
[usb] pm3 --> data autocorr w 4000
[=] performing 35999  correlations          
[+] possible correlation 3520 samples
[usb] pm3 --> data detectclock a
[+] Auto-detected clock rate: 64, Best Starting Position: 163
[usb] pm3 --> data save ../unknown_lf_tag.pm3 
[+] saved to '../unknown_lf_tag.pm3' 

What makes me wonder is that according to org repo the tag should not contain any data (the whole block is 0).


Two questions:

  • Which repo is right, should I use for lf tags?

  • Are EM 4x50 tags fully supported or is this work in progress?

Thanks!

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#2 2019-09-02 15:49:42

iceman
Administrator
Registered: 2013-04-25
Posts: 6,086
Website

Re: EM4x50 or not?

Use the one that works for your tag smile

Make a trace and share here (alt, send to me)

lf read
data save em4x50_pizza.pm3

If you feel the love,  https://www.patreon.com/iceman1001

modhex(hkhehghthbhudcfcdchkigiehgduiehg)

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