Proxmark3 community

licheca

Member

Registered: 2009-04-14

Posts: 2

Error using Crapto v 2.2

Hello. I've collected the following using the PM3 on a Mifare tag and reader:

> hi14alist
recorded activity:
 ETU     :rssi: who bytes
---------+----+----+-----------
 +      0:    :     26    
 +   4752:    :     26    
 +    919:    :     93  20    
 +   2431:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  28806:    :     47  fd  e3  93      !crc
 +  17360:    :     62  9b  dc  ff      !crc
 +   1088:    :     7a  86  1c  59  9d  e6  24  e7      !crc
 +   8664:    :     80  3a  2f  6a      !crc
 +  15407:    :     16  42  f3  6a      !crc
 +1733265:    :     26    
 +   4744:    :     26    
 +   3351:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  18847:    :     60  04  d1  3d    
 +  27374:    :     c0  bc  83  dc      !crc
 +   1088:    :     d3  9f  0f  79  9b  eb  91  de      !crc
 +   8616:    :     5c  2a  7a  e3      !crc
 +1749584:    :     26    
 +   4744:    :     26    
 +    920:    :     93  20    
 +   2423:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  18847:    :     60  04  d1  3d    
 +   1089:    :     90  a4  7a  d8  4c  cb  a5  e3      !crc
 +   8863:    :     fb  f7  2b  f3      !crc
 +  17358:    :     23  63  89  bb      !crc
 +   9704:    :     ad  85  ca  63      !crc
 +  15464:    :     e6  0c  00  32      !crc
 +1733272:    :     26    
 +   4752:    :     26    
 +    920:    :     93  20    
 +   2432:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  18951:    :     60  04  d1  3d    
 +   1088:    :     cc  e3  7f  a6  fb  5d  38  c8      !crc
 +  26127:    :     95  89  cb  a5      !crc
 +   1088:    :     45  56  2c  3c  9f  8c  2c  a3      !crc
 +   8662:    :     77  af  a1  ba      !crc
 +  15416:    :     c1  c1  6d  1f      !crc
 +1733266:    :     26    
 +   4744:    :     26    
 +    910:    :     93  20    
 +   2432:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  18895:    :     60  04  d1  3d    
 +   1089:    :     05  09  2a  39  c0  93  1b  37      !crc
 +   8919:    :     36  21  f9  d8      !crc
 +  17311:    :     60  36  c9  38      !crc
 +   9752:    :     56  86  b0  bc      !crc
 +  15414:    :     a7  6e  51  0b      !crc
 +1733274:    :     26    
 +   4744:    :     26    
 +    918:    :     93  20    
 +   2432:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  18896:    :     60  04  d1  3d    
 +   9903:    :     5c  3e  d4  27      !crc
 +  18504:    :     32  fe  6b  53  f9  bc  a4  be      !crc
 +   8623:    :     95  c8  1b  ca      !crc
 +  15414:    :     5e  66  4c  55      !crc
 +1738922:    :     93  20    
 +   2430:    :     93  70  54  cb  d7  26  6e  b3  84    
 +  18896:    :     60  04  d1  3d    
 +   9952:    :     60  2b  69  3f      !crc
 +  17359:    :     f0  04  b8  c4      !crc
 +   1088:    :     d4  38  f8  6b  ca  cf  1a  e9      !crc
 +  24079:    :     04  0d  12  04      !crc

If I'm reading this correctly I would get:

 
UID: 0x54cbd726
nt: 0xc0bc83dc
nr: 0xd39fof79
ar: 0x9beb91de
at: 0x5c2a7ae3

Now using this values with the following test program doesn't get the correct key:

#include "crapto1.h"
#include <stdio.h>

int main (void)
{
 struct Crypto1State *revstate;
 uint64_t lfsr;
 unsigned char* plfsr = (unsigned char*)&lfsr;

 uint32_t uid                = 0x54cbd726;
 uint32_t tag_challenge      = 0xc0bc83dc;
 uint32_t nr_enc             = 0xd39f0f79;
 uint32_t reader_response    = 0x9beb91de;
 uint32_t tag_response       = 0x5c2a7ae3;

 uint32_t ks2                = reader_response ^ prng_successor(tag_challenge, 64);
 uint32_t ks3                = tag_response ^ prng_successor(tag_challenge, 96);

 printf("nt': %08x\n",prng_successor(tag_challenge, 64));
 printf("nt'': %08x\n",prng_successor(tag_challenge, 96));

 printf("ks2: %08x\n",ks2);
 printf("ks3: %08x\n",ks3);

 revstate = lfsr_recovery64(ks2, ks3);
 lfsr_rollback(revstate, 0, 0);
 lfsr_rollback(revstate, 0, 0);
 lfsr_rollback(revstate, nr_enc, 1);
 lfsr_rollback(revstate, uid ^ tag_challenge, 0);
 crypto1_get_lfsr(revstate, &lfsr);
 printf("Found Key: [%02x %02x %02x %02x %02x %02x]\n\n",plfsr[0],plfsr[1],plfsr[2],plfsr[3],plfsr[4],plfsr[5]);

 return 0;
}

Can anyone please give me a pointer on what I'm doing wrong? Do I have the correct values?

Thanks.

TomBu

Contributor

From: Delft, The Netherlands

Registered: 2008-10-27

Posts: 55

Website

Re: Error using Crapto v 2.2

Hi,

<Disclaimer> n00b speaking </Disclaimer>

I've had troubles with 2.2 also and reverted back to older versions which did work.

However, your trace does not seem to include any TAG replies. I'm not sure if it's because you're using old firmware or because of bad placement of the antenna

When I do hi14alist the response includes lines like these:
+    112:  4 : TAG 36! 41  24! 79   

They seem to be absent in your trace.
Furthermore you get a lot of CRC errors, in places where you shouldn't.
Look at these sample traces:
http://www.proxmark.org/forum/topic/71/ … re-traces/

So see if you can get any TAG responses by moving your antenna and / or reflash you proxmark with, for instance, 20090416_ela.

Cheers,
Tom

licheca

Member

Registered: 2009-04-14

Posts: 2

Re: Error using Crapto v 2.2

Hello.

I've reflashed the PM3 with 20090416_ela (OS, FPGA and bootloader). I guess I'll have to check my antenna and se if I can get some TAG replies.

rule

Member

Registered: 2008-05-21

Posts: 417

Re: Error using Crapto v 2.2

Check out the FAQ in this forum, in particularly, this post

adam@algroup.co.uk

Contributor

From: UK

Registered: 2009-05-01

Posts: 203

Website

Re: Error using Crapto v 2.2

I've ported the test program to crapto1-v2.2 and made it slightly more user friendly in that it now takes it's values from the command line:

  usage: mifarecrack <UID> <TAG CHALLENGE> <READER CHALLENGE> <TAG RESPONSE> <READER RESPONSE>

  example: mifarecrack 0x5c72325e 0x50829cd6 0xb8671f76 0xe00eefc9 0x4888964f

  should produce the output:

    uid:  5c72325e
    nt':  73ba72d6
    nt'': 93c7b940
    ks2:  93b49d1f
    ks3:  db4f2f0f

    Found Key: [ff ff ff ff ff ff]

I've uploaded it and a Makefile to the uploads section - it would be useful to know if it works against other keys than the test examples I've tried...

adam@algroup.co.uk

Contributor

From: UK

Registered: 2009-05-01

Posts: 203

Website

Re: Error using Crapto v 2.2

Doh!

Got the help the wrong way around:

This:

  usage: mifarecrack <UID> <TAG CHALLENGE> <READER CHALLENGE> <TAG RESPONSE> <READER RESPONSE>

should be:

  usage: mifarecrack <UID> <TAG CHALLENGE> <READER CHALLENGE> <READER RESPONSE> <TAG RESPONSE>

which is also the order they will be read from the trace, so makes more sense!

soz!

rule

Member

Registered: 2008-05-21

Posts: 417

Re: Error using Crapto v 2.2

Moved it to the Various Software section.

adam@algroup.co.uk

Contributor

From: UK

Registered: 2009-05-01

Posts: 203

Website

Re: Error using Crapto v 2.2

Thanks for the tip. The bug was that the cracked key was output in the wrong order. I've uploaded a new version.

I've also included the -O3 in the Makefile, so use the .3 of a second you gain wisely!

adam@algroup.co.uk

Contributor

From: UK

Registered: 2009-05-01

Posts: 203

Website

Re: Error using Crapto v 2.2

I agree with the cut & paste thing and did indeed implement that last night, but I couldn't upload a new version until the old one was moved out of the way...

Usage is now:

  usage: mifarecrack <UID> <TAG CHALLENGE> <READER CHALLENGE> <READER RESPONSE> <TAG RESPONSE>
     or: mifarecrack <CUT & PASTE FROM SNIFFER LOG>

  example: mifarecrack 0x5c72325e 0x50829cd6 0xb8671f76 0xe00eefc9 0x4888964f
       or: mifarecrack 5c  72  32  5e 50  82  9c  d6 b8  67  1f  76  e0  0e  ef  c9 48! 88  96  4f

I've now uploaded it.

I'll take a look at the %qx thing - does anyone have access to a big-endian system to test it?

adam@algroup.co.uk

Contributor

From: UK

Registered: 2009-05-01

Posts: 203

Website

Re: Error using Crapto v 2.2

To make it even simpler, I've also just uploaded a python helper app 'mifarecrack.py', which will parse a full logfile:

$ ./mifarecrack.py snooper.log

Found TAG UID: da  93  96  36
Executing  ./mifarecrack da  93  96  36 64  1d  7a  09 29  56  9a  f9  c5  5a  4c  66 c2! 9a! 8f! 2a

  uid:  da939636
  nt':  4ff0d74d
  nt'': 76a5aead
  ks2:  8aaa9b2b
  ks3:  b43f2187

  Found Key: [ab cd ef 01 23 45]

adam@algroup.co.uk

Contributor

From: UK

Registered: 2009-05-01

Posts: 203

Website

Re: Error using Crapto v 2.2

I'm always interested in constructive criticism - thanks for your feedback.

To answer your specific points:

I use python because that's what I'm comfortable programming in. I'm not going to start playing with yacc/lex, but there is, of course, nothing to stop you publishing your own stuff.

I think a TAG with UID starting 60 or 61 will not fail as it will not match ':     60' or ':     61' as it will either have the word 'TAG' or a command such as '93 70' in there as well.

Whitespace is not an issue either as the output of the logfile is fixed and the final call to the external cracker strips it anyway.

It is not intended to be a general decoder, but it could of course be expanded to be one.

Finally, I realise it will fail on multiple authentications (or even if the TAG UID changes before the authentication), but this is an example program, knocked up in a few minutes,  that can be adapted as required - I follow the 'publish early, publish often' philosophy, and would rather publish something that's broken and fix it as and when the requirement arises than not publish it at all or spend more time than necessary trying to make it perfect before it's allowed to see the light of day...