Proxmark3 community

ntk

Contributor

Registered: 2015-05-24

Posts: 701

[abandoned] Have you noticed these differences ...

Running my fork,  shouldn't be different for 'lf hid' commands,     both LF SEARCH  / LF HID FSKDEMOD  works.

I suggest you recompile and flash again. After that I would start looking at LF commands to verify lF works at all.

pm3 ~/client$ proxmark3.exe com3
Prox/RFID mark3 RFID instrument
bootrom: /-suspect 2015-11-19 10:08:02
os: iceman/-suspect 2016-05-05 20:30:54
LF FPGA image built for 2s30vq100 on 2015/03/06 at 07:38:04
HF FPGA image built for 2s30vq100 on 2015/11/ 2 at  9: 8: 8

uC: AT91SAM7S512 Rev B
Embedded Processor: ARM7TDMI
Nonvolatile Program Memory Size: 512K bytes. Used: 214717 bytes (41%). Free: 309571 bytes (59%).
Second Nonvolatile Program Memory Size: None
Internal SRAM Size: 64K bytes
Architecture Identifier: AT91SAM7Sxx Series
Nonvolatile Program Memory Type: Embedded Flash Memory
pm3 --> lf se
Reading 30000 bytes from device memory

Data fetched
Samples @ 8 bits/smpl, decimation 1:1
NOTE: some demods output possible binary
  if it finds something that looks like a tag
False Positives ARE possible

Checking for known tags:

HID Prox TAG ID: 2006ec0c86 (1603) - Format Len: 26bit - FC: 118 - Card: 1603

Valid HID Prox ID Found!
pm3 --> lf hid fskdemod
#db# TAG ID: 2006ec0c86 (1603) - Format Len: 26bit - FC: 118 - Card: 1603
#db# TAG ID: 2006ec0c86 (1603) - Format Len: 26bit - FC: 118 - Card: 1603
#db# Stopped
pm3 -->

Base on Iceman post on a different thread, I put some datas in a small table together. Can you see strange things in there? differences.

Although the FC and CN are the same I see 6 differences in this attached  calculation

1/ HEX in B2 and B3 are different
2/ Binary string in C2 and C3 are different length
3/ This is HID 26bit but in C3 HEX ID found by proxmark , and converted by calculator shows a 38 bits sequence
4/ bit pattern of 2006ec0c86 is 38 bits long in calculator and in Brivo 26 bits long
5/ put 2 different HEXs (2006ec0c86 and 2EC0C86) in the Brivo, result come out are the same FC=118 CN=1603 (coincident? con or a math conversion secret here?)

Do you see the 6th difference?
I have searched on the forum and googled to find anyone raised awareness or comments on similar "differences" in the result of calculation by Brivo and the scientific calculator from the hex ID, but with no success

Last edited by ntk (2016-05-08 12:39:41)

ntk

Contributor

Registered: 2015-05-24

Posts: 701

Re: [abandoned] Have you noticed these differences ...

Sorry I made a mistake: in the column E are Bit pattern (Converted by Brivo) not from calculator.. I have just corrected the picture now .

iceman

Administrator

Registered: 2013-04-25

Posts: 9,538

Website

Re: [abandoned] Have you noticed these differences ...

The HID raw also has the formatlen encoded.
You see it more clear when you align the binary output

   2EC0C86 ::             10111011000000110010000110
2006ec0c86 :: 10000000000110111011000000110010000110

ntk

Contributor

Registered: 2015-05-24

Posts: 701

Re: [abandoned] Have you noticed these differences ...

Yes thank I did see at the HEX part EC0C86 too ... but cant not explain where the rest comes from or why the overhead...

Last edited by ntk (2016-05-07 09:53:19)

ntk

Contributor

Registered: 2015-05-24

Posts: 701

Re: [abandoned] Have you noticed these differences ...

So definitely no BUG then. sighhhh && and ...  thought have found something useful fo the team ...